The effect of removal of adherent cells in lectin and allogeneic cell stimulation of bovine lymphocytes.

Macrophages have been shown to play an important role in lymphocyte activation in many species but not unequivocally for bovine. In this study we have shown that when sufficient care is taken to remove macrophages by adherence or by anti-macrophage serum and complement, bovine lymphocytes respond poorly to lectins or to allogenic cells in mixed lymphocyte culture. Addition of macrophages to approximately the same level as found in the unseparated cells restores the proliferative responses. The degree of response shown by the macrophage depleted cultures depends on the lectin concentration. Stimulation with lower doses of lectin is more sensitive to macrophage concentration. The mixed lymphocyte response and the response to Concanavalin A (ConA) are more sensitive to macrophages than is the response to phytohemagglutinin (PHA).