Relationship between facilitated allergen presentation and the presence of allergen-specific IgE in serum of atopic patients.
Allergen presentation to allergen-specific T cells can be facilitated when IgE-allergen complexes are endocytosed by antigen-presenting cells (APC) after binding to the low-affinity Fc epsilon R type II (CD23). Here we present a study on the relative capabilities of sera of atopic patients to mediate facilitated antigen presentation (FAP). To this aim FAP was studied in an in vitro model in which CD23-expressing Epstein-Barr virus (EBV)-B cells act as APC to T lymphocyte clones (TLC) that are specific for Der p 2, a major allergen of housedust mite Dermatophagoides pteronyssinus (Dp). Der p 2 is immune-complexed by preincubation in sera from atopic patients, containing allergen-specific IgE. If EBV-B cells are preincubated with these complexes before using the cells as APC, the allergen-specific TLC proliferate at 100-1000-fold lower allergen concentration than required for T cell activation after presentation of uncomplexed allergen. The relative capability of various sera to mediate FAP was correlated with total serum IgE, and especially with Der p 2-specific serum IgE. In the model used, a high FAP capacity could be demonstrated only in sera with a total serum IgE concentration above approximately 2 micrograms/ml or with Der p 2-specific IgE above approximately 100 ng/ml. Maximal FAP, i.e. the ability to induce maximal proliferation of the TLC, was obtained in the presence of more than +/- 600 ng Der p 2-specific IgE/ml. At 100-600 ng/ml Der p 2-specific IgE the level of FAP was correlated with the concentration of allergen-specific IgE, whereas at lower concentrations FAP was low or absent. All tested sera from eczema patients, all having serum anti-Der p 2-IgE concentrations > 600 ng/ml, showed a high FAP capacity, whereas all tested sera from atopic patients without eczema, which had serum anti-Der p 2-IgE levels < 600 ng/ml, showed no or a low FAP capacity. The association of high FAP capacity with eczema may reflect a functional role of FAP in the pathogenesis of atopic dermatitis.
Academic Medical Centre, University of Amsterdam, Laboratory of Cell Biology and Histology, The Netherlands.
F L
FL
van der Heijden
R J
RJ
van Neerven
M L
ML
Kapsenberg
D000485:Allergens / Q000276:immunology; D000818:Animals; D000918:Antibody Specificity; D017951:Antigen Presentation / Q000276:immunology*; D039741:Antigens, Dermatophagoides; D002478:Cells, Cultured; D003876:Dermatitis, Atopic / Q000276:immunology; D006023:Glycoproteins / Q000276:immunology; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000276:immunology*; D007073:Immunoglobulin E / Q000097:blood* / Q000276:immunology*; D008213:Lymphocyte Activation; D008925:Mites / Q000276:immunology; D011852:Radioallergosorbent Test
D000485:Allergens; D039741:Antigens, Dermatophagoides; D006023:Glycoproteins; D007073:Immunoglobulin E