The mechanism of interaction between T and B lymphocytes in the in vitro response to sheep erythrocytes. Non-specific collaboration across a dialysis membrane.

Purified T lymphocytes from normal mouse spleen restored the antibody-forming cell response to sheep erythrocytes of various B lymphocyte populations when separated from them by a cell-impermeable dialysis or nucleopore membrane. A 2-5-fold increase occurred when spleen cells from neonatally thymectomized mice or congenitally athymic mice, and an adherent spleen cell population were used as sources of B cells. Antigen was required in both T- and B-cell compartments, but a nonspecific reconstitution occurred when the antigens present in the two compartments were different. It is concluded that during the first 20 hours of culture, T lymphocytes produce a non-specific factor in response to antigen. Although the factor acts at a distance, it does not have a non-specific mitogenic effect upon all B lymphocytes. Some of its properties are similar to those of other reported T-cell factors and of the 'sheep erythrocyte reconstitution factor', found naturally in some batches of foetal calf serum.