Human monoclonal antibodies to a genus-specific chlamydial antigen, produced by EBV-transformed B cells

Stable B cell lines producing human monoclonal antibodies to Chlamydia were established from salpingitis patients in the early convalescence phase. The antibody-producing cells were immortalized by Epstein Barr virus (EBV) transformation. Specific antibody-secreting clones were enriched by a stepwise microtiter plate cloning procedure. The selected B cell clones showed stable antibody production for more than 1 yr in continuous culture. Serologic specificity was demonstrated by micro-immunofluorescence (micro-IF) tests against a panel of Chlamydia reference strains. The antibodies were of the IgG1 subclass, and complement fixation could be demonstrated for one clone. There was no cross-reactivity against a large number of other bacteria. The monoclonal antibodies are directed against a common genus-specific surface antigen of the Chlamydia organism. Infected McCoy cells showed a brilliant, punctuated fluorescence surrounded by an inclusion membrane. Compared with conventional antisera, the monoclonal antibodies showed a clearer fluorescence pattern with very low background.