IMMUNOLOGICAL INVESTIGATIONS, 22(5), 389401 (1993)

EPIDERMAL DENDRITIC CELL POPULATIONS

IN THE FLAKY SKIN MUTANT MOUSE

John P. Sundberg, Dawnalyn Boggess, Beth A. Sundberg,

Wesley G. Beamer, and Leonard D. Shultz

The Jackson Laboratory, 600 Main Street, Bar Harbor, ME 04609 U.S.A.

A B m

Flaky skin (gene symbol: fsn) is an autosomal recessive mouse mutation that causes pathologic changes in the skin yielding a papulosquamous disease resembling human psoriasis. Preliminary studies of epidermal sheets from foot pads of fsn/fsn mice stained for Ia' Langerhans cells (LC) or Thy-1' dendritic epidermal cells (Thy-1' DEC) indicated a rise in LC numbers at the time of weaning, when the skin lesion becomes clinically evident. To further investigate this observation, epidermal sheets were obtained from the ear, dorsal skin, and foot pads from replicates of 6 female mice (both mutants and normal littermates) on weekly intervals from birth to 8 weeks of age. Dorsal skin epidermal thickness was quantitated by computer assisted image analysis and found to be significantly thickened from one week onward in the mutant mice. Using immunofluorescence microscopy, epidermal dendritic cell numbers were determined following staining with antibodies for the following markers: Ia, NLDC-145, and S-100 (for LC) or Thy 1.2 and asialc-GM1 (for Thy-1' DEC). Use of all 5 markers to evaluate skin from 3 different locations yielded a subtle but significant increase in LC and Thy-1' DEC in flaky skin mice. Of the three sites evaluated, the dorsal skin and ear epidermal sheets were most informative, which corresponded to the degree of pathological involvement. Mice doubly homozygous for f s n and for the severe combined immunodeficiency (scid) mutation developed the psoriasiform dermatitis. Bone marrow grafts from fsn/fsn homozygotes to homozygous scid/scid mice reproduce the skin lesion. These studies suggest that the psoriasiform dermatitis in the flaky skin mouse mutation is associated with abnormalities at the level of hematopoietic progenitor cells.

JNTRODUCTIOH

Psoriasis is a common, disfiguring disease of humanbeings. Although much

has been learned about the clinical variations and possible etiopathogenesis of

this disease, progress has been slow in the understanding of the basic

mechanisms, genetic influences, and development of effective therapeutic

regimens. Such progress has been hampered by the lack of a manipulatable animal

model system. Recently, a new autosomal recessivemouse mutation, known as flaky

skin (fsn), has been found to cause many pathological and biochemical changes

similar to those characteristic of psoriasis (23).

389

Copyright 0 1993 by Marcel Dekker, Inc.

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390 SUNDBERG ET AL.

The phenotype of the fsn moue is associated with abnormalities of

stratified squamous epithelia and the hematopoietic system. Skin of fsn/fsn mice

develops a patchy, thick, white scale that first becomes evident at the gross

level after weaning, about 4 weeks of age. Microscopically. affected areas

consist of prominent acanthosls, orthokeratosis with focal parakeratosis,

subcornealpustules, a mononuclear cell dermal infiltrate, and dilation of dermal

capillaries (23). The stratified squanous epithelium of the forestomachs of

affected mice, an organ for which there is no human equivalent, develops

progressive papillomas that eventually fill the lumen as the mice age. These

tumor-like lesions are not caused by a papillomavirus (24). Affected mice also

have anemia that is evident at birth (2). Mutant mice can be identified by a

palor of the ears and eyes that can be verified by assessments of packed cell

volume. The low hematocrit serves as a useful marker for distinguishing mutant mice from littermate controls before onset of gross skin lesions. Severe anemia

is not reported as a clinical feature of psoriasis although cell membrane modifications and changes in erythrocyte deformability have been described in

erythrocytes of psoriatic patients (15, 18, 19).

Development of psoriatic lesions in human beings is associated with an

epidermal influx of helper T lymphocytes and Langerhans cells ( U s ; 1). It has

been hypothesized that psoriatic lesions develop when helper T cell and antigen presenting LC functions overwhelm epidermal suppressor mechanisms (29). Activated T helper cells produce a variety of cytokines that stimulate

keratinocyte proliferation resulting in enhanced production of IL-1 by

keratinocytes. Such factors could stimulate T helper cells to generate

additional cytokines. Products of activated T helper cells could also enhance the antigen-presenting capacity of Lc (29).

Isolated case reports have indicated that bone marrow grafts from normal

individuals to those with psoriasis may ameliorate the psoriasis (7, 13). These

observations suggest that the inflammatory component of psoriasis may be a

primary part of the disease process. The epidermal hyperplasia may, therefore,

be due to factors secreted by cells derived from hematopoietic progenitors in the

bone marrow or to the activity of umture cells of bone marrow origin that have

migrated to the skin.

Epidermal dendritic cells represent an important facet of the skin's immune

system (4, 22, 27). Langerhans cells promote T cell activation (12) and have been implicated as a stimulus for keratinocyte proliferation (6). Two major types of dendritic cells reside in the murine epidermis. These are the LCs and

the CD4'. CDK. Thy-1' dendritic epidermal T cells (Thy-1' DEC; 1, 3, 28). Both

cell populations are derived from bone marrow (5, 14). These cells are present in mouse epidermis and their numbers vary with age (20), immunologic status (21) , and other factors.

The present study investigates the density of dendritic cell populations

in the murine epidermis relative to aging, development, and progression of

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EPIDERMAL DENDRITIC CELL POPULATIONS 39 1

psoriasifornlesions. Preliminary studies have indicated that the hematopoietic stem cells of the bonenarrow are necessary for production of the fsn phenotype

since the cutaneous phenotype occurs following transfer of fsn/fsn bone marrow

into scld/scfd mice. However, functional lymphoid cells are not required for development of the skin lesion.

mTERIALS AND METHODS Mice. The fsn mutation occurred on the A/J strain background. Because

homozygotes (fsn/fsn) failed to thrive, fsn is being back crossed onto several inbred strains, including the BAU/cByJ. The current investigation was carried

out with BALB/cBy fsn/fsn and littermate control (+/fsn or +/+, hereafter

referred to as +/TI mice at the 3rd to 5* generation. Replicates of a minimum of 6 homozygous (fsn/fsn) and normal littermate control (fsn/+ or +/+, hereafter

+/?) mice were obtained from our research colony at The Jackson Laboratory (Bar

Harbor, ME). Tissues from mice were sampled at weekly age intervals beginning

at 1-2 days of age to 8 weeks of age. Additional replicates of 6 mice were used

for the first two week age groups to obtain adequate amounts of ear and foot pad

epidermis. All mice were kept at three to four animals per cage on sterilized pine bedding, fed a standard diet of Wayne Lab Blox (Teck Lab Premier Laboratory

Diets, Bartonville, IL), and received chlorinated tap water ad libitum.

Epidermal Separation. Nice were euthanized by COz asphyxiation prior to shaving

with electric clippers followed by depilation (Nair; Carter Products, New York, NY). Skin was removed from the foot pads, ears, and dorsal thoracic regions.

Each skin sample was incubated 30 minutes at 37% in 5% COz:95% air in a 8.2 g/l

solution of Na,EDTA-2H20 in distilled water (pH 7.3; adjusted with 1.0 M NaOH), then incubated for two hours at 37% in 5% C0,:95% air in an 8.2 g/l solution of Na,EDTA-2H20 buffered with 116 mM NaC1, 2.6 mM KC1, 8 mM NazHPO,, and 1.4 mM

KHzPO, (pH 7.3; adjusted with 1.0 H NaOH). The epidermis was then mechanically

separated from the dermis and washed in phosphate buffered saline (PBS; pH 7.3)

prior to subsequent treatments. Representative epidermal sheets taken from

dorsal skin, fobt pad, and ear were fixed and processed as described below for

routine histologic examination to verify the efficiency of the dermal-epidermal separation.

Monoclonal Antibodies and Polyclonal Antisera. The primary antibodies used, their type, specificity, and source, are listed in Table 1. Corresponding secondary FITC conjugated antibodies (goat anti-rat IgG, rabbit anti-mouse IgG,

and goat anti-rabbit IgG; Sigma Chemical Co., St. Louis, MO) were purchased. Immunofluorescence Microscopy. Epidermal sheets were fixed for 20 minutes at

23% in acetone. Specimens were washed three times in PBS containing 5% fetal calf serum (FCS; HyClone Laboratories, Inc., Logan, UT) at 4% for 10 minutes

each before incubation with the appropriate primary antibody in a total volume of 200 pl. The specimens were then incubated at 4OC for 16 hours and washed three times at 23OC for 40 minutes each in FCS. The sheets were then incubated

for 100 minutes in the appropriate FITC-conjugated antiserum. Lastly, the

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392 SUNDBERG ET AL.

Table 1. epidermal T cells.

Antibodies and antisera used to identify Langerhans cells and dendritic

Antibody Type Specificity Source+

Ia Rat Monoclonal Langerhans cells ATCC

NLDC-145 Rat Monoclonal Langerhans cells Dr. G. Kraal

s - 100 Rabbit Polyclonal Langerhans cells DAKO

Thy-1.2 Mouse Monoclonal Thy- 1' DEC ATCC

AS -GM1 Rabbit Polyclonal Thy-1' DEC WAKO

+ ATCC - American Type Culture Collection Hybridoma DAKO - DAKO Gorp., Carpinteria, CA. WAKO - Uako BioProducts, Richmond, VA.

specimens were washed three times in PBS on a rocker platform for 40 minutes each

at 23'C, mounted using fluoromount-G (Fisher Scientific, Pittsburgh, PA) and

examined with a fluorescence microscope equipped for epi-illumination. Total number of labeled cells were counted within a single field at 1OOOX. The field

was calculated to have an area of 0.025 mm'. Twenty fields. chosen at random,

were counted for each epidermal sheet for a total area of 0.51 m'. Epidermal Haasurements. A portion of skin w a s fixed by itarnersion in Fekete's

acid-alcohol-formalin solution (25)' processed routinely, paraffin embedded,

sectioned at 6 pm, and stained with hematoxylin and eosin. The thickness of the

entire epidermis was measured using a microscope with an image analyzer

(PrecisionGraphics Systems, Saco, ME). Aminimum of 25 randommeasurements were

taken and analyzed using Sigmascan and SigmaPlot software (Jandel Scientific,

Corte Madera, CA). Bone amrrov grafts. Bone marrow was removed from two fsn/fsn and two +/? mice

and injected, via the tail vein, into three C.B. 17-scid/scid recipients for each

donor. The mice were observed for 10 weeks, at which time they were necropsied. Skin was

collected and processed routinely for histologic examination.

Doubly homozygous fsn/fsn scid/scfd mice. Ovaries from the N5 backcross

generation of BALB/cBy.A/J-fsn/fsn mice were grafted into the ovarian bursa of

ovariectomized C.B17-scid/scidrecipients. The recipient females were then mated

to BALB/cByJ-scid/scid males. The F1 offspring were backcrossed to scid/scid mice and were identifiedby the absence of circulating I&. The scid/scid,+/fsn

backcross mice were mated with known +/fsn breeders. The F, offspring that

developed lymphocytic depletion, anemia, and hyperplastic skin disease are

A dose of lo7 cells in minimum essential media was injected.

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EPIDERMAL DENDRITIC CELL POPULATIONS

Epidermal Thickness

0.09 1 0.08

0.07 h

0.06 W

.- c 0.05 in

S Y

c

0.04

.O- 0.03 I-

0.02

0.01

-1

393

I 0 +/? 1 0.. ...,

'"fL .................................... 0. .................................... - ........ 0

.' . ... .. ...' . ., . . . ..'.

0.00 I I I I I I I I 1

0 1 2 3 4 5 6 7 8

Age in Weeks

FIGURE 1

Epidermis thickened with age in fsn/fsn mice but thinned significantly in normal littermate controls.

homozygous for both mutations. Although several litters have been born containing these double mutants, only one pair of 6 week old females

(fsn/fsn,scid/scid; +/?,scfd/scid) was necropsied. From these, all major organs

were processed routinely for histologic evaluation.

Statistics. Experimental group mean and standard error were calculated for each

experiment. Comparisons of group means were performedby using one way ANOVA and student "t" tests for evaluation of epidermal thickness data. Each antibody was

evaluated for genotype effects across tissues by the Mann-Whitney U test.

Differences between values were considered statistically significant at pcO.05.

RESULTS Epidermal Thickness. The data in Pig. 1 show that there was no effect of the fsn mutation on epidermal thickness at birth. Thickness increased then decreased in

mice of both genotypes during the first and second weeks of life. However, from week two on normal mouse epidermis remained thin while that of the fsn/fsn aice increased significantly (p < 0.0001) in thickness through 4 vteeks and remained thick over 8 weeks. Differences in epidermal thickness between fsn/fsn and +/?

control mice were significant by week 1, however, histologic features were not consistently different until week 3, because of the variation in thickness at the younger ages.

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394 SUNDBERG ET AL.

FIGURE 2

Normal 6 week old female dorsal skin ( A ) had a thin epidermis with little cellular activity in the dermis while the epidermis of the age and sex matched fsnffsn ( C ) mouse was markedly thickened with numerous mononuclear cells in the dermis. Epidermis of normal (B) and fsnlfsn (D) skin separated completely from the dermis using the methods described. (H&E X 100)

Dendritic Cell Denaity in the Epidermis. Dermal-epidermal separation techniques

yielded clean separations of skin from dorsal skin, ears, and foot pads (Fig. 2). Langerhans cells were identified by their long dendritic processes and intense

staining with Ia, NLDC-145 and S-100 (Fig. 3A). Thy-1' Dendritic epidermal cells

were similar in appearance but had short dendritic processes (Fig. 3B). Changes in numbers of LC and Thy-1' DEC were subtle but statistically

significant (Table 2). Figure 4 is representative of the types of results obtained over time for LC and Thy-1' DEC, respectively. For LC, numbers were consistently higher at all ages in the ear, increased after 4 weeks of age in the foot pads, and elevated after 3 weeks in the dorsal skin. Mean numbers of LC in fsn/fsn epidermis from all three sites were consistently higher than normals for

each of the three antibodies used. This trend was significant (p <0.025) by

Mann-Whitney U test. The asialo GM1 antibody revealed the same mean elevation

of Thy-1' DEC in fsn/fsn epidewal sheets. Numbers of Thy-1' DEC were

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EPIDERMAL DENDRITIC CELL POPULATIONS 395

FIGURE 3

Positive immunofluorescence of Ia+ Langerhans cells (A, arrowheads) and Thy-l.2+ DEC (B, arrowhead). (X 4 0 0 0 )

consistently elevated at all ages in the ear, as was found for LC. There was an

overall increase in numbers, but this varied at the different ages for the foot

pad. Asialo-GM1' cells were increased in numbers of dorsal skin at all ages in

the fsn/fsn mice, with major increases between 2 and 4 weeks of age. However,

the anti-Thy 1.2' antibody was uninformative.

Bone marrow grafts. Injection of bone marrow from fsn/fsn mice into 6 scid/scid mice yielded mice with no anemia or gastric papillomas. However, these mice

developed a mild dorso-cranial alopecia. Microscopically, there was marked

acanthosis and orthokeratosis with focal microabscess formation. Vessels were

dilated and there was a moderate mixed inflammatory cell infiltrate in the

dermis. These changes are consistent with the microscopic phenotype of the fsn

mutation. The littermate control bone marrow did not cause any lesions in

scid/scid recipients.

Double mutants. The doubly homozygous fsn/fsn,scid/scid mice were produced on

the BALB/cBy partially inbred background. The affected fsn/fsn.scid/scid mouse

examined had gastric papillomatosis, low packed cell volume (19%), and epidermal

hyperplasia similar to the features that are typical of fsn/fsn mice. In

addition, the double mutant had a spleen that was similar in size to a normal

BALB/cByJ mouse but smaller that an age matched fsn/fsn and larger than that of

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Table 2.

epidermis obtained from fs

n/fs

n and

+/?

littermate female mice aged 1 to 56 days.

different antibodies using indirect imunofluorescence as described in the Methods section.

on 6 mice at 7 ages.

Density of Langerhans cells and Thy-1' dendritic epidermal cells in ear, dorsal skin, and foot pad

Cells were identified by five

Each mean is based

Cell types &

Ear

Dorsal Skin

Foot Pad

antibodies

fsn/

fsn

+/?

fs

n/fs

n +/

? fs

n/fs

n +

/?

Janeerhans cells

#

Ia+

592+93

446+56

451263

371258

7152130

6572100

#

s-100

462

9

312 6

372 8

29+ 7

36+

6 27+

5

#

NLDC-145

96234

62229

102227

64215

422

8 555 22

p-

#

Asialo GM1

442 6*

302

3 65;t14*

322 6

332

3 302

2

Thy 1.2+

55211

512 7

94219

98226

54210

44+

7

# fs

n/fs

n significantly higher that

+/?

by Mann-Whitney U test (nl,n2 - 1

8), p<O.O.25

* indicates fs

n/fs

n significantly higher that

+/?

by students "t"

test, p <

0.05

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n E E a L V

In

0) U

(n

- -

a L 0

9

N

E E

a L 0

VI

Q - -

VI 0 a L O

9

n E E

a L 0

W

v 0

L1

- -

0 a .c 0

e

1200

300

0 - 1 0

1200

900

600

300

0

1200

900

600

300

0

EAR la POSITIVE DENDRlTlC CELLS

EAR

ASIALO GMl POSITIVE DENDRlTlC CELLS

120 1

I 1 1 2

"E E 90 { 0 n

3 4 5 6 7 8 9 - 1 0 1 2 3 4 5 6 7 8 9

Age in Weeks 0 Control Age in Weeks

f sn / f sn FOOT PAD FOOT PAD

la POSITIVE DENDRlTlC CELLS

J 1 -1 0 1 2 3 4 5 6 7 8 9

Age in Weeks

DORSAL SKIN la POSITIVE DENDRlTlC CELLS

-1 0 1 2 3 4 5 6 7 8 9

Age in Weeks

ASIALO GMl POSITIVE OENDRlTlC CELLS

lZO 1 E

n - i 5 60

n'

; 30 0

ah

0 -1 0 1 2 3 4 5 6 7 8 9

120

n E E 90 m a n 5 60

bi

5 30

L

-

P

'1;

0

Age in Weeks

DORSAL SKIN ASIALO CM1 POSITIVE OENDRITIC CELLS

- 1 0 1 2 3 4 5 6 7 8 9

Age in Weeks

FIGURE 4

Changes in epidermal dendritic cell populations with age. Representative results for Langerhans cells are illustrated by Ia+ staining and for Thy-l+ dendritic epidermal cells by asialo GM1 staining of dorsal skin, ear, and foot pad epidermal sheets.

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398 SUNDBERG ET AL.

a scid/scid. Microscopically, the spleen was hypercellular due to marked

erythropoiesis, a feature of fsn/fsn. The control (+/-,scid/scid) mice had no

gastric or cutaneous abnormalities, a normal packed cell volume ( 4 6 % ) and

generalized lymphoid depletion, identical. to the phenotype of a scid/scid mouse.

DISCUSSION The flaky skin mouse mutation causes a hyperplastic skin disease that

resembles human psoriasis (23). Bone marrow grafted from fsn/fsn into scid/scid

mice reproduced the skin lesion indicating a primary role of the bone marrow in

the cutaneous disease process. Langerhans cells and Thy-1' DEC are bone marrow

derived cells that normally reside in mouse epidermis and are likely candidates

for controlling disease related epidermalchanges. Quantitative changes in these

cell populations did reveal significant increases in both LC and Thy-1' DEC that

imply possible a role in the cutaneous disease process. Functional assays of

Langerhans cells and Thy-1' DEC are needed to determine what that role might be

in the disease processes. These studies are in progress.

Psoriasis is a common inflammatory skin disorder affecting approximately

2% of the population in the United States (9, 10). This disease presents

clinically as red, scaling, symmetrical plaques. Microscopically, these plaques

exhibit epidermal hyperplasia, altered keratinocyte differentiation, dermal T cell and macrophage infiltrates, and dilated bloodvessels (16). Quantitatively,

psoriatic skin contains increased numbers of monocytes, Langerhans cells, and T cells indicative of an ongoing cellular immune reaction (10, 29).

The dermal dendrocyte is another bone marrow-derived macrophage that may

represent a different immunophenotypic expression of LCs (16). Cyclosporin A,

which is commonly used to treat psoriasis ( 8 ) . causes a decrease in the numbers

of T cells, Langerhans cells, and monocytes in lesions, however, their numbers were unchanged relative to the total number of immune cells. In contrast, dermal

dendrocytes, which are present in psoriasis but not in normal skin, were

essentially cleared with cyclosporin A (10). These results suggest that

Langerhans cells within the dermis probably play a minor role, if any, in the

pathogenesis of psoriasis.

The mouse equivalent of human dermal dendrocytes were not investigated in

this study and may prove to be important. However, the human dermal dendrocytes are of bone marrow origin and may represent a different stage of Langerhans cell maturation.

Double mutants (fsn/fsn,scid/scfd), were created to specifically remove

parts of the immune system. The scid mutation results in mice that lack B and T cells as well as Thy-1' DEC (26, 17). Mice, determined to have the scid

mutation based on absence of circulating immunoglobulin, still developed

psoriasiform dermatitis in the double mutants. This indicates that neither B nor T cells are required for development of the psoriasiform dermatitis.

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EPIDERMAL DENDRITIC CELL POPULATIONS 399

The methods used to quantitate dendritic cells in affected areas of skin

have been controversial. Human studies have evaluated numbers of cells in

vertical tissue sections as well a8 in epidermal cell suspensions (10). Previous studies in our laboratories have indicated that evaluation of epidermal sheets,

in which all positive nuclei are counted throughout the specimen by focusing

through the tissue. yielded reproducible results on thick foot pads of several mouse strains and mutations (20, 21). We modified that epidermal separation

method in order to obtain epidermal sheets from depilated haired skin with no

dermal remnants. Neonatal (fsn/fsn and +/-) and normal adult skin were easily

stained and evaluated in this study. The fsn/fsn epidermis increased markedly in thickness with age. Although positive staining was detected in all sections, it is possible that dendritic cells in the middle of the sheet were not

adequately stained resulting in less positive cells being counted than were

actually present. Vertical sections were evaluated by both immunoperoxidase and

immunofluorescence techniques. Due to the extreme thinness of normal adult

epidermis and difficulty in identifying dendritic processes in 6 pm sections,

this approach was abandoned (Sundberg and Boggess, unpublished data).

Previous studies using mice have identified similar numbers of LCs in

epidermal sheets regardless of the antibodies used (21). In the current study,

Ia' dendritic cells were more numerous that NLDC-145' cells, which were more

numerous than S-100' cells. The flaky skin mouse mutation has numerous

inflammatory cells infiltrating into both the dermis and epidermis. Such severe

inflammation is different from the rhino, nude, and viable motheaten mutations

previously evaluated (21). Antibodies used in this study were not exclusively

specific for U s . The variability in numbers detected by each antibody most

likely represents cross reaction with certain inflammatory cells migrating

through the epidermis. Alternatively, subpopulations of LCs or variations in

surface antigens due to differentiation and activation status, may exist. Two

of the three antibodies detect cell surface markers in the intact cells in the

epidermal sheet preparations. On the other hand, the antibody directed against S-100 protein, a cytoplasmic protein, is poorly accessible to an intact cell

(11). Langerhans cell and Thy-1' DEC populations have been studied in aging mice

of several strains as well as in several mouse mutations maintained on the same

inbred background (20, 21). Both absolute numbers and function vary widely, although useful data can be obtained within an inbred strain. The fsn mutation

was difficult to maintain on the A/J strain on which it arose spontaneously as

well as on C57BL/6J congenic strain (Shultz, Beamer, Sundberg, unpublished data).

The mutation is currently maintained on a congenic BALB/cBy background which was at the 3" to Stb generation of backcrossing when used for this study. As a

result. the mutation was on a partially inbred background, therefore background gene effects may still be affecting the expression of fsn. The epidermal

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400 SUNDBERG ET AL.

dendritic cell observations described here will be confirmed when the congenic strain has been backcrossed to the N10 or greater generation where 98% of the background genome will be homozygous for BALB/cBy alleles.

A!xmiLmEMENTS This work was supported by grant number AR40324 from the National Institute

of Health. The authors thank P. Jewett for histology services, B. Gott for the

fsn/fsn,scid/scid colony management, and T.H. Hahn, a participant in our summer student program, for assistanc.e in technique development.

1. 2.

3.

4. 5 .

6 .

7.

8.

9. 10.

11.

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13. 14. 15.

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REFERENCES

K.W. Baker and J.E.J. Habowsky, J Invest Dermatol 80, 104-107 (1983). W.G. Beamer, L.J. Maltais, and S.E. Bernstein, Annual Scientific Report, The Jackson Laboratory, pp. 92-93 (1987). P.R. Bergstresser, R.E. Tigelaar, J.H. Dees, and J.W. Streilein, J Invest Dermatol u, 286-288 (1983). A . S . Breathnach, J Invest Dermatol a, 6-11 (1980). S.M. Breathnach and S.I. Katz, J Invest Dermatol 83, 74-77 (1984). L.C. Chow and D.N. Saunder, J Leuk Biol 3, 343-358 (1986). D.J. Eedy, D. Burrows, J.M. Bridges, and F.G.C. Jones, Br Med J 300, 908 (1990). C.N. Ellis, D.C. Gorsulowsky, T.A. Hamilton, J.K. Billings, M.D. Brown, J.T. Headington, K.D. Cooper, 0. Baadsgaard, E.A. Duell, T.M. Annesley, J.G. Turcotte, and J.J. Voorhees, J Am Med Assoc u, 3110-3116 (1986). E.M. Farber and H.L. Nall, Dermatologica m, 1-8, (1974). A.K. Gupta, 0. Baadsgaard, C.N. E:llis. J.J. Voorhees, and K.D. Cooper, Arch Dermatol Res 281, 219-226 (1989). M. Haftek, in Psoriasis, Znd ed., H.H. Roenigk and H.I. Maibach, eds., Marcel Dekker, Inc., New York, (1991) pp. 343-370. H. Hirschberg, L.R. Braathen, and E. Thorsby, Immunological Rev 66, 57-77 (1982). S.N. Jowitt and J.A.L. Yin, Br Xed J 300, 1398-1399 (1990). D.I. Katz, K. Tomaki, and D.H. Sachs, Nature 282, 324-326 (1979). R. Kumar, V.C. Weiss, D.P. West, and L.A. Chiero, Br J Dermatolm, 267- 275 (1983). B.J. Nickoloff and C.E.M. Griffiths, Autoimmunity Forum 1, 2-4 (1989). J.L. Nixon-Fulton, P.L. Witte, R.E. Tigelaar, P.R. Bergstresser, and V. Kumar. J Immunol 138, 2902-2905 (1987). F. Perocco, G . Clari, A. Peserico, and V. Moret, Acta Derm Venereol (Stockh) j&, 48s-49s (1989). A. Peserico, C. Veller-Fornasa, R Cipriani, G. Perenzin, and R. Codolo, Arch Dermatol Res m, 390-391 (1988).

Imm

unol

Inv

est D

ownl

oade

d fr

om in

form

ahea

lthca

re.c

om b

y Se

rial

s U

nit -

Lib

rary

on

10/1

2/12

For

pers

onal

use

onl

y.

EPIDERMAL DENDRlTIC CELL POPULATIONS 401

20.

21.

22.

23.

24.

25.

26.

27.

28.

29.

E. Sprecher, Y. Becker, G. Kraal, E. Hall, D. Harrison, and L.D. Shultz, J Invest Dermatol g, 247-253 (1990). E. Sprecher, Y. Becker, G. Kraal, E. Hall, and L.D. Shultz, Arch Dermatol RsS 282, 188-193 (1990). G. Stingl, K. Tamaki, and S. Katz, Immunological Rev 3, 149-173 (1980). J.P. Sundberg, W.G. Beamer, L.D. Shultz, and R.W. Dunstan, J Invest

Dermatol s, 62s-63s (1990). J.P. Sundberg, G. Kenty, W.G. Beamer, and D.L. Adkison, J Vet Lab Invest

in press.

J.P. Sundberg and D.R. Roop, J Histochem Cytochem, in press. J.P. Sundberg and L.D. Shultz, Comp Pathol Bull submitted.

R.E. Tigelaar, J.M. Lewis, and P.R. Bergstresser, J Invest Dermatol 94, 58s-63s (1990).

E. Tschachler, G. Shuler, J. Hutterer, H. Leibl, K. Wolff, and G. Stingl, J Invest Dermatol &&, 282-285 (1982). H. Valdimarsson, B.S. Baker, I. Jonsdottir, and L. Fry, Immunology Today z, 256-259 (1986).

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est D

ownl

oade

d fr

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s U

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Lib

rary

on

10/1

2/12

For

pers

onal

use

onl

y.