The association of alpha2-macroglobulin with lymphocyte membranes in chronic lymphocytic leukaemia and other disorders.

The association of alpha2-macroglobulin (alpha2M) with the surface membranes of human peripheral blood lymphocyte preparations has been investigated by the direct immunofluorescent technique. The percentage (and total number) of lymphocytes with detectable alpha2M on their surface is significantly increased in chronic lymphocytic leukaemia. The incidence of alpha2M-positive cells in normal and pathological conditions closely parallels that observed with conjugated antiserum to the kamma and gamma light chains of human immunoglobulin. It bears no relationship however to the plasma alpha2M levels or to the age of the donor. Additional blocking studies with aggregated human IgG, soluble antigen-antibody complexes and the F(ab')2 moiety of the anti-alpha2M, and indirect immunofluorescent studies with the latter, indicate that the fluorescence observed is not due to interaction of the conjugated reagent with Fc or C3 receptors.