SEROLOGICAL AND IMMUNOCHEMICAL CHARACTERIZATION OF MONOCLONAL-ANTIBODIES TO TOXOPLASMA-GONDII

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  • 1 January 1980
    • journal article
    • research article
    • Vol. 40  (4) , 579-588
Abstract
The fusion of mouse NS-1 myeloma cells with spleen cells from mice chronically infected with T. gondii resulted in 8 clones of hybridomas producing monospecific antibodies against membrane or cytoplasmic antigens of Toxoplasma tachyzoites. One of the antibodies to a cytoplasmic determinant was an IgM; the others directed to membrane or cytoplasmic antigens belonged to the IgG2 or IgG3 isotypes. Antibodies of clones 1E11 (IgG3), 2G11 and 3E6 (IgG2) directed to membrane antigens, bound complement and were reactive in the complement-dependent cytotoxicity assay of Sabin-Feldman. These IgG2 antibodies were strongly agglutinating to parasites; the IgG3 was relatively weak. Another IgG2 antibody (5B6), possibly recognizing a shared antigen of membrane and cytoplasm, exhibited a low titer in the cytotoxicity assay and in the agglutination assay. Two other antibodies to membrane antigens (2B7 and 2F8) and an antibody to a cytoplasmic antigen (3G3) did not bind complement and did not cause agglutination. The pattern of parasite staining produced by monoclonal antibodies to membrane antigens in an IFA [indirect fluorescent antibody] test was different from that of polyvalent antisera. A strictly localized or beaded staining was observed as was a smooth, rim fluorescence. Toxoplasma tachyzoites were surface radio-iodinated and the solubilized membrane proteins were immunoprecipitated with monoclonal antibodies and analyzed by 2-dimensional polyacrylamide gel electrophoresis. Two independently arising monoclonal antibodies to membrane antigens (2G11 and consistently precipitated the solubilized 35,000 and 14,000 MW proteins; 1E11 precipitated the 27,000 MW protein.