Phagocytosis of murine lymphoma cells by macrophages. II. Differences between opsonic and cytotoxic activity of mice immunized with lymphoma cells.

Primary allogeneic antiserum raised in C57B1 mice directed against a DBA/2 lymphoma, L5178Y, was found to contain at least two types of opsonic activity associated with the γ-globulin fraction of the antiserum. One was found at a low level corresponding to cytotoxic activity, binding strongly to L5178Y cells and resistant to treatment with mercaptoethanol. The other, which accounted for most of the opsonic activity, was relatively non-specific for L5178Y cells, was easily eluted from the cells, was not associated with cytotoxicity and was sensitive to mercaptoethanol treatment. Two types of opsonic activity were also found in allogeneic antiserum against the CBA/2 lymphoma, TLX5. Both types of lymphoma antisera opsonized sheep red cells, but anti-sheep red cell serum was highly specific, exhibiting no degree of opsonic cross-reactivity with either type of lymphoma cell.