Studies on immunity in hybridoma-bearing mice. A. Immune response to antigens. II. inhibition of production of anti-dinitrophenyl antibodies in mice which have rejected the B 53 anti-dinitrophenyl-producing IgE hybridoma.

When BALB/c mice, which had rejected the anti-dinitrophenyl (DNP) IgE-producing hybridoma B 53, were immunized with DNP proteins, they produced much less anti-DNP antibodies than control (normal) mice. The anti-DNP plaque-forming cell (PFC) number was much less when spleen cells from mice immunized with DNP proteins were treated with sera of mice which had rejected the hybridoma B 53 than the PFC number from the same spleen cells not treated by the sera. The sera of mice which had rejected the hybridoma B 53 contained an inhibitor which was adsorbed and eluted from an anti-mouse immunoglobulin column and also a mouse anti-DNP IgG2a column. The inhibition of PFC was hapten-reversible. In Western blotting the eluates from the anti-DNP IgG2a column reacted as well with the blotted anti-DNP IgE B 53 as an anti-idiotypic antibody to anti-DNP IgE B 53. These criteria establish that the inhibitor in the sera of the mice which had rejected the B 53 tumor was an anti-idiotypic antibody of the type which mimics the epitope (DNP) of the immunizing antigen.