IL-4 production by allergen-stimulated primary cultures: identification of basophils as the major IL-4-producing cell type.
As a potent inducing agent for IgE production and differentiation factor for allergen-specific Th2 cells, IL-4 is a key regulatory cytokine both in the pathogenesis of allergic disease and in the ongoing allergic response. The assay of in vitro IL-4 production has often been used to compare the allergen responses of T cells isolated from atopic and non-atopic subjects. Because peripheral blood basophils also have the capacity to respond to specific allergen by producing IL-4, we investigated the relative contribution of these two cell types to IL-4 production in allergen-stimulated primary cultures. Among unfractionated peripheral blood mononuclear cells (PBMC), the major producers of detectable IL-4 in primary in vitro cultures were found to be basophils based on: (i) an allergen dose-response corresponding closely to that required for basophil histamine release and lower than that required for T cell activation; (ii) a rapid time course for IL-4 production (detectable at 3 h), inconsistent with the typical activation requirements of fresh T cells; (iii) the production of comparable levels of IL-4 in cultures stimulated with allergen or anti-IgE; and (iv) the complete loss of detectable IL-4 production following specific depletion of basophils from PBMC. The T cells in these cultures were functionally able to produce IL-4, as demonstrated by mitogen activation of basophil-depleted PBMC. These findings demonstrate that although IL-4 production in primary in vitro cultures can be used as a sensitive indicator of allergen responsiveness, the accurate interpretation of this result requires identification of the responding cell type. Furthermore, these findings raise the possibility that basophil production of IL-4 early in the course of allergen stimulation may shape subsequent T cell responses both in vivo and in vitro.
Kasaian
M T
MT
ImmuLogic Pharmaceutical Corp., Waltham, MA 02154, USA.
Clay
M J
MJ
Happ
M P
MP
Garman
R D
RD
Hirani
S
S
Luqman
M
M
D000485:Allergens / Q000008:administration & dosage*; D000818:Animals; D001491:Basophils / Q000166:cytology / Q000276:immunology*; D002415:Cats; D002478:Cells, Cultured; D006197:Hair / Q000276:immunology; D006636:Histamine Release; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000276:immunology; D015847:Interleukin-4 / Q000096:biosynthesis*; D015848:Interleukin-5 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008934:Mitogens / Q000494:pharmacology; D013601:T-Lymphocytes / Q000276:immunology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000485:Allergens; D015848:Interleukin-5; D008934:Mitogens; D015847:Interleukin-4; D013755:Tetradecanoylphorbol Acetate