Formation of IgE-binding factors by rat T lymphocytes. IV. Mechanisms for the formation of IgE-suppressive factors by antigen stimulation of BCG-primed spleen cells
Hirashima, M.; Uede, T.; Huff, T.; Ishizaka, K.
Journal of Immunology 128(4): 1909-1916
1982
ISSN/ISBN: 0022-1767 PMID: 6977574 Document Number: 193093
Incubation with purified protein derivative (PPD) of spleen cells of rats primed with BCG resulted in the formation of soluble factors having affinity for IgE, i.e., IgE-binding factors. The IgE-binding factors consisted of 2 different molecules; 1 had a MW of 60,000-80,000 and another molecule had a MW of 10,000-20,000. The IgE-binding factors of both high and low MW selectively suppressed the IgE response of dinitrophenyl-ovalbumin (DNP-OA) primed cells to homologous antigen. Analysis of the cellular mechanisms of formation of IgE-suppressive factors revealed that the presentation of PPD to BCG-primed T cells by macrophages resulted in the formation of soluble factors that in turn induced normal (mesenteric lymph node (MLN) cells to form IgE-suppressive factors. Fractionation of the soluble factors from BCG-primed T cells on Poly U-Sepharose showed that 2 different factors, i.e., inducers of IgE-binding factor and glycosylation-inhibiting factors, were involved in the selective formation of IgE-suppressive factors. The eluate fraction from Poly U-Sepharose induced normal MLN cells to form IgE-binding factors that had marginal suppressive activity on the IgE response. The effluent fraction from the beads failed to induce IgE-binding factors but contained soluble factors that inhibited the glycosylation of IgE-binding factors during their biosynthesis and provided them with a biologic activity: suppression of the IgE response. The latter fraction also inhibited the IgE-induced expression of IgE Fc receptors on the cell surface. In the BCG-primed spleen cells, the major source of both inducers and glycosylation-inhibiting factors were W 3/25 (-) T cells; the IgE-suppressive factors were derived from W 3/25 (+) T cells. Antigen-primed W 3/25 (-) T cells apparently release both inducers and glycosylation-inhibiting factors upon stimulation with PPD and these factors in combination stimulate W 3/25 (+) T cells to form IgE-suppressive factors.