Molecular Characterization of the Element Controlling the Genetic Restriction of the B-B Cellular Interaction.

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Immunization of BALB/c mice with MOPC104E myeloma protein induces antiidiotypic B lymphocytes that have idiotype-specific enhancing activity on antibody production. The B-B cell interaction was restricted to both Igh and class II MHC. However, anti-Thy-1 and complement treated splenic B cells were maintained for more than 1 year in a mixture of concanavalin-A-stimulated splenocyte culture supernatand and synthetic medium. In applying the long term culture method, we have established a cloned B cell line named B19-1^d. B19-1^d cell are specific to MOPC104E or J558 cross-reactive idiotype and they express surface mu, lambda but no Ly-1. B19-1^d do not spontaneously secrete immunoglobulin but produce them upon stimulation with bacterial lipopolysaccharides. The effect of B19-1^d cell line on idiotypic antibody production was tested. Addition of only 10 to 100 B19ー1^d cells into dextran immune B cell culture greatly enhanced the idiotype-positive antidextran antibody responses. On the contrary, the antidextran antibody production was suppressed by the higher doses of B19-1^d cells. The effective cooperation between dextran-immune B cells and B19-1^d cloned B cells was restricted to class II MHC. By fusing lipopolysaccharide-stimulated B19-1^d clone with P3U1 myeloma, antiidiotypic antibody producing hybridoma was established.Each hybridoma cDNA and MOPC104E genomic DNA was cloned and their nucleic acid sequences were determined. The sequences were highly similar each other (91% similarity) and it was suggested that the both genes were derived from closely linked germ line genes.