Histamine sensitivity infbmces reactivity to attergens

Martin S. Stuckey, M.B., B.S., F.R.A.C.P., Campbcdf S. Witt, Ph.D., Lincoln H. Schmitt, Ph.D.,* Robert Warlow, M-B., B.S., F.R.A.C.P., Margaret Lattimore, R.N., and Roger L. Dawkins, M.D., F.R.A.C.P. Perth, W. Australia

The ability to mount an IgE response to allergens is a prerequisite for the development of positive allergen skin tests, and this is reflected to some extent by the observation that allergen-responsive subjects tend to have higher total serum IgE concentrations. To determine whether histamine sensitivity also contributes to allergen responsiveness, 893 subjects in u rural community were prick tested with 14 allergens and tenfold dilutions of histamine phosphate beginning at I mglml-‘. IgE was measured in a subset of 400 subjects. Three-way contingency table analysis confirmed previous reports of an association between allergen responsiveness and IgE (p < 0.001) and also demonstrated that allergen responsiveness is associated with sensitivity to histamine (p < 0.001). This association is independent of IgE so that the additive effect of IgE and histamine sensitivity allows more nearly accurate prediction of allergen responsiveness than either measurement alone. (J ALLERGY CLIN IMMJNOL 7.5:373-6, 1985.)

Reactivity to an allergen depends on previous exposure and genetic factors influencing IgE re- sponses.‘” Although there is a correlation between serum 1gE concentration and allergen responses,4” the relationship does not allow allergen reactivity to be accurately predicted from the IgE concentration. Clearly there must be other factors that determine allergen responsiveness. This study examines the vari- ation in sensitivity to histamine between subjects and explores the interactions of these three variables.

MA I. AND METHODS subjects

During the 1981 Busselton Health Survey, five consec- utive subjects from every 15 who had the same appointment time were prick te$ed with allergens and histamine. There was a total of 893 subjects with a slight excess of female

Fmm the *Department of Anatomy and Human Biology, University of Western Australia, Perth, W. Australia.

Received for publication Dec. 27, 1983. Accepted for publication Aug. 1, 1984. Reprint requests: M. Stuckey, M.B., Department of Clinical Im-

munology, Royal Perth Hospital, Wellington St., Perth, 6oo0, W. Australia.

Publication 82107 of the Departments of Clinical immunology, Royal Perth Hospital and The Queen Elizabeth II Medical Center, Nedlands. W. Australia.

1”L’““..xdj HTC: Htstamrne threshold concentmtlon

subjects (470). The range in ages was from 18 to 86 yr with a mean of 49.5 yr. More than 95% of the population were able to trace the family origins to the United Kingdom.

Allurgen amd hiiina WI All subjects were prick tested by the method of Pepys’

with 14 alfergens including six local grass p&ens, two weeds, one tree pollen, cattle and dog dander& and Aqer- gillus and Dermatophagoides farinae extracts in 50% g&c- erinated saline (Hollister-Stier Labs, Spokane, Wash.). All allergens were of the same lot numbers and were used at a 1: 10 dilution as recommended by the manufatnrer. Afier- gens were selected from previous knowledge of&e Ilergens most commonly causing allergic symptoms in the southwest of Western Australia and the prevalence of vtius weeds and grasses in the survey area. There are virtually no de- ciduous trees in the area studied. Histamine pric;lk testing was performed with four concentrations of his&mine &IS- phate (1.0, IO-‘, IO-‘, and IO-’ mg/mf-‘) diluted in 0.9% saline. The concentrations are for histamine plloaphate, not histamine base, and 0.9% saline was used a6 a negative control. Two perpendicular diameters of whe& WE* mea- sured 15 min after pricking, and the mean of the two di- ameters was recorded. All testing was completed in a 2-

313

374 Stuckey et al.

60

50

40

30

FREQUENCY

10

0

HI~AMINE THRESHOLD

CONCENTRATION fmy.ml.‘)

FIG. 1. Distribution of HTC in 893 subjects.

TABLE 1. Relationship between histamine sensitivity and allergen responsiveness

No. of positive

allergens HTC al.0 HTC = 0.1 HTC s 0.01 mglml-’ mglml-’ mg/ml-’

0 317 (56) 121 (54) 10 (11) 1 to 5 I58 (28) St (23) 28 (30) >6 87 (15) 53 (24) 56 WI

Totals 562 (100) 225 (100) 94 (100)

Figures are for the number of subjects in each category with per- centages in parentheses; x3 = 106.4, p < 0.001.

week period during November 1981 to include the height of the local pollen season. All tests were performed between the hours of 7:30 A.M. and 1:OO P.M.

IgE concentration Serum IgE concen~ations were determined for a subset

of 400 subjects by PRIST (Pharmacia Diagnostics, Uppsala, Sweden). Subjects were selected for one of three reasons: (1) the subject had previously been found to have a positive bee sting RAST (n = llO), (2) the subject had been previously typed for hist~ompatibility antigens (selection for hist~ompatibi~~ antigens typing was at random) (n = 220), and (3) the subject was part of a family study on IgE (families were not selected for allergic symptoms or high IgE) (n = 70).

The percent bound radioactivity in the PRIST assay was converted to IU ml-’ by means of a standard curve obtained

J. ALLERGY CLIN. IMMUNOL.

MARCH 1985

TABLE II. Relationship between IgE concentration and allergen responsiveness

No. of positive IgE ~25 IgE 26 to 100 IgEBlOl

allargens IU ml-’ IU ml-’ IU ml-’

0 117 (66) 53 (43) 12 (12) 1-5 43 (24) 45 (37) 24 (33) >6 16 (9) 24 (20) 56 (55)

Totals iz(100) 122 (100) 102 (100)

Figures are for the numbers of subjects in each category with per- centages in parentheses; x: = 104.5, p < 0.001.

by use of standard sera supplied with the kits. For each serum sample IgE concentration was reported as the mean of two determinations. For values below 10 IU ml-‘, the mean difference in IgE units between two determinations was 0.37 IU ml-‘. Sera with values of 10 IU ml-’ or higher had a mean variation of 7.3%.

Calculation of histamine sensitivity and allergen reactivity

The lowest concentration of histamine producing a wheal of at least 2 mm in diameter after subtracting the diameter of any saline wheal was designated the HTC for that subject. Subjects not resending to 1 .O mgiml-’ histamine were con- sidered to have an HTC of > 1 .O mgimi”.

Allergen reactivity was defined as the number of allergens producing a wheal diameter of >2 mm after subtraction of any saline wheal.

Reproducibility of prick tests was assessed on 2 1 subjects who were tested on 2 cons~utive days. Of a total of 420 repeated tests, 110 tests were positive both days, 24 tests were positive on the first day but not on the second, 17 tests were positive on the second day but not on the first day, and 269 tests were negative on both days.

Statistical analysis

For the purpose of statistical analysis, subjects were clas- sified into the following groups: HTC: 3 1 .O mg/ml-’ , 0.1 mg/ml-‘, and GO.01 mg/ml-‘; serum: IgE 0 to 25,26 to 100, and 3101 IU ml-‘; allergen reactivity: 0, 1 to 5, and >5 allergens positive; and age: 18 to 29, 30 to 49, 50 to 69, and >69 yr. All statistical analyses were performed with the GLIM statistical package8 with the use of contingency tables and a log-linear model.

RESULTS Range of histamine sensitivii

Fig. 1 illustrates the dis~bution of HTC. Only 4.8% of the population responded to 0.001 mg/mP of histamine, whereas over 90% responded to 1 .O mg/ ml-‘. HTC did not differ significantly between sexes (xi =I: Lt.@, but older subjects tended to be more sen- sitive (i.e., lower HTC) (~2 = 21.4, p < 0.005).

VOLUME 75

NUMBER 3 Reactivity to akrgens 375

FBI& 2. Associations of IgE and HTC with allergen responses. The vertical axis and the num!yeus in tke &ure represent the percentage of subjects in each of the nine groups who reacted to six or more aftergens.

There was a sign~c~t relationship between aller- gen ~~~sive~ss and HTC as illustrated in Table I (xi = 106.4, p < 0.001). A higher proportion of subjects with a low HTC reacted to at least six aller- gens compared to subjects with a high HTC. Thus higher sensitivity to histamine was associated with re~tions to a large number of aIlergens.

There was a slight decrease in allergen responsive- ness in older subjects (.xi = 21.6, p < 0.05).

There was an as~iation between sernm IgE con~en~ti5~ and allergen responsiveness as would be predicted from previous studieP (x: = 104.5, p < 0.001). Table II illustrates that a higher propor- tion of subjects with high IgE reacted to at least six aifergens cornpa& to subjects with low IgE.

Older subjects tended to have iower IgE concen- trations (xi = 17.0, p < 0.005) as did female sub- jects (x$ = 8.6, p < 0.025). Three-way analysis illustrated that sex and age cannot explain the asso- ciation between IgE and allergen responsiveness.

histamine tration with

alleqpm respmsiveness

Since both HTC and IgE are associated with aller- gen ~~onsiven~ss~ it was irn~~~t to determine whether the HTC-alfergen response association was secondary to an HTC-IgE association. Fig. 2 dem-

6

I

4 1 1) * @ 0

3 1

sub@cts with an l-X& of O.oOP mg&W L higher than that of the rest of the poputatir~n tp -C 0.001, Student’s t test).

onstrates that allergen res~nsiv~~s i~~~aaes as ei- ther IgE increases or HTC increases. Three-way anal- ysis of the data illustrated that the aviation of increased histamine sensitivity with reactions to large numbers of allergens is independent of 1gE concen- tration (xi = 5.8, not signi~~t)~ i.e., sjnce HTC and IgE ~on~n~at~o~ are in~~~~~t in t&&r efkcts on allergen responsiveness, their effwts a~ ad$itive.

Although for most of the population, there is no relationship between HTC and I& ~o~~~~t~tio~~ it was found that subjects with the St ~itivi~ to histamine (HTC = 0.001 rng~rn~~) also had in- creased IgE concentrations (Fig. 3).

370 Stuckey et al.

Since the study group was not randomly selected for IgE, separate analyses were performed on each of the three subgroups. The same association: were ap- parent in all three subgroups.

DISCUSSION

We have demonstrated that histamine sensitivity is related to the ability to respond to specific allergens by prick testing and that this effect is independent of the association between IgE concentration and aller- gen responses. This allows prediction of allergen re- sponsiveness from the other two measurements. For example, if a response to at least six allergens is pre- dicted for subjects with IgE concentration >lOO IU ml’ and HTC SO.01 mg/ml-‘, 89% would be correctly classified. Conversely, if a lack of response to aller- gens was predicted for subjects with IgE concentration ~25 IU ml-’ and HTC al.0 mg/ml-‘, 97% would be

correctly classified. Barbee et a1.6 found relatively little influence of

histamine sensitivity on allergen reactivity and found no correlation between histamine sensitivity and age between the ages of 20 to 65 yr. A trend toward higher sensitivity with increasing age was clear in the present study, although the difference was more marked be- tween younger age groups than between older age groups. These differences between data of Barbee et al. and our own may be due to our use of a range of histamine concentrations for the measurement of histamine sensitivity rather than a single concen- tration.

Whether histamine sensitivity has a direct effect on allergen responsiveness or is a result of previotic al- lergen reactivity is not known. In support of the former is some preliminary evidence that histamine sensitivity is genetically determined.’

Alternatively, repeated stimulation of histamine re-

J. ALLERGY CLIN. IMMUNOL. MARCH 1985

ceptors by histamine, as occurs in allergic subjects, may result in upregulation of the receptor. Such an effect has been suggested by the observation that bron- chial histamine sensitivity increases after exposure to allergens. ‘O

We gratefully acknowledge the assistance of Ms. J Lock- hart (art work), the BusseltonStudies Group, TVW Telethon

Foundation, and the Western Australian Department of Puh- lit Health.

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