Formation of rat IgE-binding factors by rat-mouse T cell hybridomas.

Mesenteric lymph node (MLN) cells of rats infected with Nippostrongylus brasiliensis (Nb) were obtained 8 days after infection and were incubated overnight with rat IgE for the formation of IgE-binding factors. These cells were then fused with BW 5147 mouse T lymphoma cells. Two hybrid clones (A4 and B6) obtained by the fusion formed IgE-binding factors upon incubation with IgE. It was found that 1-hr incubation with 3 micrograms/ml of rat IgE was sufficient to induce hybridoma cells to form IgE-binding factors. Both hybrid clones express rat T cell markers; the A4 clone bears Fc epsilon R, whereas the B6 clone bears Fc gamma R on their surface. The IgE-binding factors formed by both clones bound to rat IgE-coated Sepharose and could be eluted from the beads at pH 3.0. The factors also have affinity for mouse IgE but not human IgE nor rat IgG. IgE-binding factors formed by the A4 clone had a m.w. between 26,000 and 30,000; the B6 clone formed IgE-binding factors of 26,000 and 13,000 daltons. The factors of both high and low m.w. failed to bind to lentil lectin and Con A, but had affinity for peanut agglutinin. Purified IgE-binding factors of 13,000 daltons selectively suppressed the IgE-forming cell response of DNP-ovalbumin-primed MLN cells to homologous antigen, whereas the factor of 26,000 to 30,000 daltons neither suppressed nor enhanced the IgE response.