Abstracts 39

0.5 1

I P = 0.63, p < 0.001

l

0 j_ i____- __ I ___~__ -

0 50 100 150

Liver PCB (pg/g lipid wt.)

Fig. 1. Change in microsomal CYP450 concentration with

increasing liver PCB concentration (pg/g lipid weight) showing

induction of P450 protein.

0.9

0.6 c B !i 0.7

r 0.6

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1 l

l l

l IL l l l

l

l l

0 50 100

Liver PCB (Fg/g)

150

Fig. 2. Rate of progesterone metabolism per mg total protein

with increasing liver PCB concentration (w/g lipid weight).

Poster Abstracts

The Effect of Penicillin, a Prototypic Drug Allergen, on the Expression of Ceil Surface Markers in Human Dendritic Cell Cultures

Mary Scott and Clive Meredith Immunology Unit, Molecular Sciences Department, TNO-BIBRA International Ltd, Woodmansterne Road, Carshalton, Surrey SM5 4DS, UK

In order to develop an in vitro system with the capacity to identify potential drug allergens, we have focused on the development of cultures of the dendritic cell (DC), a professional antigen presenting cell, and the study of the way in which they might influence Thl/Th2 lymphocyte development. Using the drug, penicillin,

40 Abstracts

as a prototypic allergen, cultures of DC have been established and the effect of allergen on the expression of co-stimulatory molecules involved in T cell activation was considered as a possible end-point. It was also important to show that DC modified by the allergen treatment could influence the profiles of T cell activation; we characterised this parameter in terms of Thl/ThZ cytokine expression.

Using in-house volunteers as blood donors, grouped as either atopic (n = 3) or non-atopic (n = 3) (but not allergic to penicillin), DC cultures were established from peripheral blood mononuclear cells (PBMC) stimulated with granulocyte macrophage-colony stimulating factor (GM-CSF) (12.5 ng/ml) and interleukin 4 (IL-4) (10 ng/ml) for 5 days. Cells were then cultured in the presence of penicillin for 24 h at concentrations of 0,0.5 and 1 .O mg/ml. Analysis of cell surface marker expression by flow cytometry revealed that exposure of DC to penicillin induced both up- and down-regulation of certain co-stimulatory molecules and that there were differences between atopics and non-atopics. For example, DC from atopics revealed a two-fold increase in expression of CD40 relative to non-atopics. In the presence of 1.0 mg/ml penicillin, CD40 expression in atopics reduced by approximately 40% relative to untreated controls. Conversely, the expression of CD86 in DC from atopics increased by approximately 80% in the presence of 1.0 mg/ml penicillin.

Using a similar experimental protocol, DC developed in vitro for 5 days were exposed to penicillin for 24 h, then used to stimulate a mixed lymphocyte reaction (MLR) using purified PBMC obtained from the same donors. Cultures were maintained for a further 5 days, then stimulated with phorbol 12-myristate 13-acetate (PMA) (2.5 ng/ml) and ionomycin (1.5 ng/ml) for 3, 24 or 48 h. IL-4 or IFNy mRNA was measured using dot-blot hybridisation using radiolabelled cDNA probes.

mRNA levels in penicillin-haptenated DC-stimulated MLR measured 3 h post PMA/ionomycin stimulation (densitometric units)

IL-4 IFNy

Pen (mg/ml) 0 0.5 1.0 0 0.5 1.0 Atopic 990 1376 2257 4235 6078 11 956 Non- atopic 214 329 290 19 567 18 964 13 256

These dose dependent changes in cytokine expression were reflected at all three time points studied, suggesting that the modification of DC by the drug allergen, penicillin, was having an effect on the profile of T cell development. Taken together with the data on CD40 and CD86 regulation by penicillin, these results suggest that it is possible that an in vitro system can be developed, based on the culture of DC from PBMC from atopic and non-atopic volunteers, which may be predictive for the effects of allergenic drugs. Supported by EU Biotechnology programme - contract B104 CT 960246.

Changes in Total Serum IgE Concentration in the Brown Norway Rat Following Topical Exposure to Respiratory and Contact Allergens

E.V. Warbrick, R.J. Dear-man, I. Kimber AstraZeneca Central Toxicology Laboratory, Alderley Park, Macclesfield, Cheshire SK10 4TJ, UK

Exposure to a variety of chemicals in the workplace can cause sensitisation of the respiratory tract and occupational asthma which is often associated with the production of IgE antibody. Topical exposure to chemical respiratory allergens such as trimellitic anhydride (TMA) has been shown previously to induce