[Attempts to improve hybridoma technology for the production of human monoclonal antibodies].

The technology for producing hybridomas secreting human monoclonal antibodies has not been well established, contrary to the situation for mouse monoclonal antibodies. Therefore, we attempted to find better fusion partners using two EBV-transformed human B cell lines, C5TK1 and TAPC-30 (anti-SRBC IgM and anti-HBs IgG secretors, respectively; provided by Prof. Y. Ono, Nihon Univ. School of Med.). Fifteen partner cell lines available were fused with either of these lines by conventional PEG technique, and their fusion frequencies, cloning efficiencies, and levels and stabilities of specific antibody secretion were examined. Among the fusion partners tested, KR-12, SHM-D33 and 3HL3-6J lines appeared to be the best. Hybridomas with the KR-12 line were easily cloned and produced stable specific antibodies, although the level of Ig secretion was almost the same as the antibody-producing parental B-cell lines. SHM-D33 cells efficiently formed hybrids but the stability of their Ig production was low and cloning was laborious. Although the fusion frequency of 3HL3-6J cells was not so high, some hybrids were good producers of antibodies, and the levels of specific antibody reached levels greater than 10 micrograms/ml. Their cloning was relatively easy. Therefore, the 3HL3-6J line seemed to be the best fusion partner for EBV-transformed B cells. With regard to the low fusion frequency of human cells, we attempted to improve the efficiency using the electrofusion technique. Three to 10 times more hybridomas were obtained by this technique than by the conventional PEG method. Further investigations are under way.