Does IL-4 play a role in the expansion of V beta 8a T cell receptor-bearing cells?
BACKGROUND
Peripheral blood mononuclear cells (PBMC) of subjects allergic to the insect-derived allergen Chi t 1--9 are characterized by an allergen-induced pronounced proliferation and increased expression of activation markers (CD25, HLA-DR, CD23). T cell lines showed an elevated percentage of V beta 8a-positive cells following stimulation by Chi t 1--9.


OBJECTIVE
The aim of the present study was to investigate whether V beta 8a dominance plays an important role in PBMC short-term cultures (24 h) as well. The role of exogenous added cytokines, especially IL-4, has been determined.


METHODS
The T cell receptor repertoire was measured with 16 monoclonal antibodies to epitopes on the variable region of the beta chain by flow cytometry. Patients allergic to Chi t 1--9 were compared to nonallergic subjects as well as to subjects with other occupational allergies. In addition, cytokines were determined intracellulary by flow cytometry. Studies were performed with PBMC cultured for 24 h.


RESULTS
After cultivation for 24 h without or with different stimuli (cytokines, allergen, phytohaemagglutinin), changes in the T cell receptor profile and the cytokine profile were measurable compared to the baseline value (without cultivation). Stimulation with IL-4 revealed increased percentages of V beta 8a-expressing cells in Chi t 1--9-sensitized patients. This IL-4-induced V beta 8a increase did not occur in PBMC from the two control subject groups (non-allergic and allergic to other allergens than Chi t 1--9). CONCLUSION In conclusion, the dominance of certain T cell receptor types seems to arise due to the exposure to specific allergens and cytokine production. Some T cell receptors are often affected, for example V beta 8a, whereas others only show minor variations. V beta 8a expression obviously plays an important role in Chi t 1-9 allergy.
Liebers
V
V
Berufsgenossenschaftliches Forschungsinstitut für Arbeitsmedizin, Institut an der Ruhr-Universität Bochum, Bochum, Deutschland. liebers@bgfa.ruhr-uni-bochum.de
Gellert
B
B
Raulf-Heimsoth
M
M
Baur
X
X
D000485:Allergens / Q000276:immunology; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology; D005434:Flow Cytometry; D006454:Hemoglobins; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology*; D019476:Insect Proteins; D015847:Interleukin-4 / Q000494:pharmacology*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008213:Lymphocyte Activation / Q000187:drug effects; D010835:Phytohemagglutinins / Q000494:pharmacology; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis*
D000485:Allergens; C071697:Chi t I allergen; D016207:Cytokines; D006454:Hemoglobins; D019476:Insect Proteins; D010835:Phytohemagglutinins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D015847:Interleukin-4