Analysis of the human tonsil B cell repertoire by somatic hybridization: occurrence of both "monospecific" and "multispecific" (auto)antibody-secreting cells.

The purpose of our study was to investigate the (auto)antibody repertoire of human tonsil B cells. To this end, unseparated tonsil B cells and "large" and "small" tonsil B cells, obtained after fractionation on a discontinuous Percoll gradient, were fused with the (human X mouse) heterohybridoma K6H6/B5. The IgM antibodies secreted by individual clones were analyzed in spot-enzyme-linked immunosorbent assay for reactivity against a panel of 5 autoantigens and 1 xenoantigen. The results show that both "mono-" and "multispecific" (auto)antibody-secreting clones can be obtained by somatic hybridization of unseparated, "small" and "large" tonsil B cells. The patterns of IgM reactivities in these three collections of hybridomas did not differ significantly. Inhibition experiments revealed that "multispecific" antibodies can bind with high affinity to more than one (auto)antigen. The results of these experiments are discussed in relation to the state of activation of tonsil B lymphocytes.