CD4+ cells proliferate after peanut-extract-specific and CD8+ cells proliferate after polyclonal stimulation of PBMC of children with atopic dermatitis

Authors


Laan Department of Immunology, Erasmus University Rotterdam, PO Box 1738, 3000 DR Rotterdam, The Netherlands.

Abstract

Background

Few studies describe in vitro food-allergen induced proliferative responses and cytokine production of PBMC of children with atopic dermatitis. This is especially true for peanut-allergen.

Objectives

To analyse the specificity of the T cell in proliferative responses, in children with atopic dermatitis with or without peanut allergy and healthy age-matched children.

Methods

Proliferative responses were measured by [3H]-thymidine incorporation and by expression of the intracellular Ki67-antigen using flow cytometry after antigen-specific stimulation of PBMC with peanut-extract (day 7) or polyclonal stimulation with Phorbol-12myristate-13acetate and Ca-ionophore (day 3). Cytokine mRNA (Interferon-gamma (IFNγ), IL-4) was detected by semiquantitative RT-PCR. Cytokine production (IL-4, IFNγ) was measured by ELISA.

Results

Peanut-extract induced proliferative responses of PBMC from children with atopic dermatitis and peanut allergy (AD+PA+) were significantly higher as compared with the other groups studied. Ki67-antigen double staining revealed that 80–100% of the proliferating cells were CD4+. These proliferative responses correlated significantly with the increase in IL-4 mRNA expression after peanut-extract specific stimulation. After polyclonal stimulation, however, CD8+ cells preferentially proliferated. The degree of proliferation after polyclonal stimulation correlated inversely with the ratio of IL-4/IFNγ production.

Conclusions

The principal responding population of T cells in proliferative responses is different after peanut-extract specific and polyclonal stimulation of PBMC from AD+PA+ patients. Furthermore, we found indirect evidence that the PBMC fraction of AD+PA+ children contains increased frequencies of peanut-specific T helper-2 cells.

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