Maximal T cell IL-13 production requires monocyte or monokine participation.
The T cell-secreted lymphokine interleukin 13 (IL-13) exerts pleiotropic effects on monocytes (Mphi) and B cells. Since accessory cells, like Mphi and B cells, also act in antigen-presenting and lymphokine augmentation of T cells, Mphi and B cells may be able to effect T cell IL-13 production. Purified T cells produced slightly less IL-13 than the lower T cell numbers contained in peripheral blood mononuclear cell population, further suggesting accessory cell augmentation. Addition of 10% B cells [either unstimulated or pokeweed mitogen (PWM)-stimulated] to autologous T cells only moderately augmented T cell IL-13 levels. PWM-stimulated B cell culture supernates had even less augmenting effect on T cell IL-13 levels and unstimulated B cell culture supernates did not augment T cell IL-13 production. In contrast to the moderately augmenting effect of B cells or their stimulated culture supernates, addition of 10% Mphi, either unstimulated or muramyl dipeptide (MDP)+IFN-gamma stimulated, to autologous T cells produced a highly significant increase in T cell IL-13 production. Mphi culture supernates were equally effective in augmenting T cell IL-13 levels, suggesting both that cell-to-cell contact is not critical for Mphi augmentation of T cell IL-13 levels, and that Mphi secreted factors are pivotal. CD64(+) Mphi (or their culture supernates), which are known as poor antigen-presenting cells, also effectively augmented T cell IL-13 production, further supporting the involvement of Mphi secreted factors. Finally, experiments with exogenous addition of recombinant monokines, as well as neutralization experiments with different cytokine antibodies, suggested IL-1beta as a primary cytokine involved in the augmentation of T cell IL-13 levels by accessory cells. However, these experiments also indicated other unidentified Mphi factors as playing a significant role in producing maximal T cell IL-13 production.
University of Massachusetts Medical Center, Worcester 01655, USA.
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D000938:Antigen-Presenting Cells / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology; D002450:Cell Communication / Q000276:immunology; D006801:Humans; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000378:metabolism; D018793:Interleukin-13 / Q000096:biosynthesis*; D009000:Monocytes / Q000276:immunology*; D015846:Monokines / Q000276:immunology*; D017452:Receptors, IgG / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology*
D007375:Interleukin-1; D018793:Interleukin-13; D015846:Monokines; D017452:Receptors, IgG