Formation of IgE-binding factors by rat T lymphocytes. VI. Cellular mechanisms for the formation of IgE-potentiating factor and IgE-suppressive factor by antigenic stimulation of antigen-primed spleen cells

Analysis of cellular mechanisms of formation of IgE-binding factors by KLH-primed spleen cells revealed that the presentation of KLH to KLH-primed T cells by adherent cells resulted in the formation of lymphokines that in turn stimulated unprimed lympocytes to form IgE-binding factors. Lymphokines released from KLH-alum-primed spleen cells induced normal lymphocytes to form IgE-potentiating factors, whereas those released from KLH-CFA-primed spleen cells induced the formation of IgE-suppressive factors. Fractionation of the lymphokines from KLH-primed spleen cells and analysis of cell sources of the lymphokines revealed that multiple factors are involved in the selective formation of one or the other IgE-binding factors. Thus, KLH-alum-primed splenic T cells form 'inducers' of IgE-binding factors and glycosylation-enhancing factors upon antigenic stimulation, and these factors in combination stimulate unprimed W 3/25⁺ Fc(γ)R⁺ T cells to form IgE-potentiating factors. Antigenic stimulation of KLH-CFA-primed T cells results in the formation of the 'inducers' and glycosylation-inhibiting factors, and these two lymphokines collectively stimulate unprimed W 3/25⁺ Fc(γ)R⁺ T cells to form IgE-suppressive factors. Cell sources of 'inducers' are W 3/25⁺ Fc(γ)R^- T cells, cells different from the source of IgE-binding factors. The glycosylation-enhancing factor is derived from W 3/25⁺ F(γ)R⁺ T cells in KLH-alum-primed spleen; the glycosylation-inhibiting factor is derived from OX 8⁺ T cells in KLH-CFA-primed spleen. Evidence was obtained that these lymphokines, which modulate the protein glycosylation of IgE-binding factors during their biosynthesis, are derived from antigen-primed T cells and determine the nature of IgE-binding factors formed.