The effect of anti-alpha2-macroglobulin on K-cell cytolysis and T- and B-cell rosette formation.

The effect of antisera to human alpha2-macroglobulin (alpha2M) on the ability of human peripheral blood lymphoid cells to lyse antibody coated target cells (exert a K-cell effect) and form T(E) and B(EAC) rosettes has been investigated. Pretreatment of lymphoid cells with these antisera inhibited their K-cell activity but had no effect on their capacity to form T or B rosettes. The inhibitory activity of the anti-alpha2M sera was always reduced following absorption on a CnBr column to which human alpha2M had been coupled. The absorbed antibody, recovered by acid elution reacted strongly with human alpha2M in gel diffusion precipitin analysis and caused a highly significant inhibition of K-cell cytotoxicity. It was further shown that the inhibitory activity of the anti-alpha2M was localized exclusively in the IgG fraction and was greatly reduced following pepsin digestion.