Hybridoma-derived monoclonal immunoglobulin M antibodies to Legionella pneumophila serogroup 1 with diagnostic potential.

Mouse hybridomas were isolated by fusing P3-X63-Ag 8.653 myeloma cells with spleen cells from mice that had been repeatedly immunized with Legionella pneumophila serogroup 1 organisms. In one fusion, three independent hybridoma cultures which secreted antibodies that reacted with the immunizing strain in the indirect immunofluorescent-antibody test were selected for cloning. Representative continuously growing clones, one of each hybridoma, which remained stable in producing high-titer antibodies were examined in detail. Extensive specificity tests revealed that these hybridoma-derived monoclonal antibodies were specifically directed against L. pneumophila serogroup 1 organisms and showed no cross-reactions in the indirect immunofluorescent-antibody test either with the other known serogroups of L. pneumophila or with other unrelated bacterial species. The three monoclonal antibodies F4/CB5/K18, F/4CB5/K104, and F4/JD3.8/K101 belonged to the immunoglobulin M class and were capable of agglutinating serogroup 1 organisms of L. pneumophila exquisitely. These monoclonal antibodies against L. pneumophila with defined fine specificity should enable purification and subsequent analysis of the corresponding antigenic determinant(s) and can also be used for the preparation of unlimited supplies of standard diagnostic reagents for the identification of L. pneumophila in the tissues and body fluids.