A pomona serogroup-specific, agglutinating antigen in Leptospira, identified by monoclonal antibodies.

Monoclonal antibodies were produced by hybridoma cell lines derived by fusion of mouse NS-1 myeloma cells with splenocytes from mice immunized with Leptospira interrogans serovar pomona. One hybridoma (A3) produced an IgG2a antibody which agglutinated all leptospires of the Pomona serogroup but not leptospires representative of serovars of any other serogroup. The antibody precipitated in immunodiffusions with either alkali- or phenol-extracted lipopolysaccharide and also with the TM antigen of Yanagawa et al., indicating a common determinant on both antigens. A3 antibody opsonized viable leptospires for phagocytosis by mouse macrophages in vitro.