THE MODULATORY EFFECT OF ANTIIDIOTYPIC ANTIBODY ON HYBRIDOMA CELLS SECRETING ANTIBODY TO HUMAN MYELIN BASIC-PROTEIN PEPTIDE 80-89

The idiotype (ID) of an antibody is postulated to be involved in immunoregulation by means of the immune network. This hypothesis was examined by stuying the effect of a monoclonal antibody (MAb) anti-ID on hybridoma cells secreting an ID-bearing MAb, 845D3, to human myelin basic protein (MBP) peptide 80-90. The monoclonal anti-ID (IgM/kappa), reacted with heavy and light chains of 845D3, an IgG1/kappa MAb, but not with a control MAb of the same isotype specific for an MBP peptide differing by one amino acid residue. Fluorescence-activated cell sorting revealed IgG heavy and kappa light chains on the surface and in the cytoplasm of 90% or more of the 845D3 cells. The anti-ID did not react with the surface of the 845D3-secreting cells, and reacted with the cytoplasm of 14-18% of these cells. In spite of the absence of cell surface ID, the anti-ID significantly decreased antibody production by the ID-secreting cells. There was no effect of the anti-ID on control hybridoma cells secreting MAb to another MBP peptide. Anti-ID exerted no cytotoxic effect on ID-bearing hybridoma cells and in fact caused a marginal increase in their proliferation compared to control MAb. These results indicate that an anti-ID may alter the antibody production of ID-secreting cells in a specific manner and without cytotoxicity. This may be one of the means for controlling an immune response against MBP generated by the cells of the immune system or in situ within the nervous system. The cellular mechanism(s) for this effect remains to be defined. © 1990.