Regulatory role of IgE-binding factors from rat T lymphocytes. IV. Formation of IgE-binding factors in rats treated with complete Freund's adjuvant.

Mesenteric lymph node (MLN) cells from rats treated with complete Freund's adjuvant (CFA) spontaneously released soluble factors, which have affinity for IgE (IgE-binding factors). The factors were purified by absorption of culture filtrates of the lymphocytes with IgE-Sepharose followed by elution at acid pH. Purified IgE-binding factors selectively suppressed IgE-forming cell response of DNP-ovalbumin-primed MLN cells to homologous antigen without affecting the IgG2 response. Fractionation of purified IgE-binding factors on lentil lectin-Sepharose showed that the majority of IgE-binding factors did not have affinity for lentil lectin, whereas a minor fraction was bound to the lectin-coupled beads. It was found that IgE-binding factors lacking affinity for lentil lectin suppressed IgE response, whereas those eluted from lentil lectin-Sepharose selectively enhanced IgE response. Serum of CFA-treated animals also contained both IgE-suppressive factor and IgE-potentiating factor, and the amount of the former factor was more than the latter. The source of IgE-suppressive factor is non-B lymphocytes. Depletion of Fc, receptor(+) lymphocytes in MLN cells from CFA-treated animals did not affect the formation of IgE-suppressive factor, indicating that Fc epsilon R-bearing cells are not the source of the factor.