Immune response regulation by lymphocyte products. Potentiator and suppressor factors detected during responses to concanavalin A, E. coli lipopolysaccharide and dinitrophenylated bovine serum albumin.

The efferent lymph from immunostimulated popliteal lymph nodes of sheep was analysed for modulatory effects on the in vitro response of peripheral blood lymphocytes to phytohemagglutinin. Both efferent lymph and the supernates prepared from lymph cells exhibited potentiating activity when collected during the first 6 hours of responses to Concanavalin A and dinitrophenylated bovine serum albumin.² Cells collected on the third day of responses to these antigens and to E. coli lipopolysaccharide produced supernates that almost totally suppressed the in vitro response. The possible contribution made by these cells and cell products to the regulation of the immune response in vivo is discussed.