Role of beta 1H for the binding of C3b-coated particles to human lymphoid and phagocytic cells.

Coating of EAC14oxy23b with highly purified human serum beta 1H globulin (beta 1H) led to acceleration of rosette formation with human peripheral blood lymphocytes (PBL), tonsil lymphocytes, B lymphoblastoid (Raji) cells, granulocytes and monocytes. This reaction was discernible from C3bi-dependent rosette formation. Enhancement of rosette formation of C3b cells by beta 1H was most effective at limiting amounts of C3 per EAC14oxy23b. The beta 1H effect was not due to trace contamination with C3b inactivator. beta 1H-dependent rosette formation with the various lymphoid and phagocytic cells could be suppressed by the F(ab')2 fragment of anti-beta 1H suggesting beta 1H-mediated binding of beta 1H-coated particles to complement receptor-positive (CR+) cells. In turn, binding of fluid-phase beta 1H to lymphoid and phagocytic cells could be demonstrated by fluorescence and by 14C-labeled beta 1H. In addition, the functional status of these cells with respect to their receptor reactivity was altered. Treatment of normal lymphocytes (PBL, tonsil lymphocytes) and of granulocytes with beta 1H improved their rosette formation with both EAC14oxy23b and EAC14oxy23b-beta 1H. The reaction of monocytes was hardly affected. The beta 1H effect on Raji cells resulted in reduced rosette formation with EAC14oxy23b-beta 1H, while binding of EAC14oxy23b remained unchanged. These results suggest the presence of sites on CR+ cells, to which soluble and particle-bound beta 1H can bind, leading to alteration of the functional status of the cells. In all likelihood, EAC14oxy23bi can attach to the beta 1H-binding sites on CR+ cells.