Immunosuppression by lymphokine-activated murine killer cell line with B-lymphoblast-lytic activity in vitro

The in vitro immunosuppressive effect caused by a murine lymphokine-activated killer cell line with B-lymphoblast-lytic activity was studied. The cloned cells (named BC-1.10, phenotype Thy 1.2+, LFA-1+, TCR-alpha beta-, TCR-gamma delta-, Fc gamma RII-, CD2-, CD3 epsilon-, CD4-, CD8- and express mRNA of zeta chain) suppressed LPS-induced Ig synthesis by B lymphoblasts previously stimulated with LPS. Phase-contrast microscopy indicated disappearance of B lymphoblasts at 24 h after the addition of BC-1.10 cells. This suppressive effect was reduced when BC-1.10 cells were pretreated with anti-LFA-1 mAb, which inhibits cytotoxicity of this clone. These data suggest that the immunosuppressive effect of BC-1.10 is due to an elimination of B lymphoblasts, and that one of the physiological functions of lymphokine-activated killer (LAK) cells, which are induced as a consequence of immune reactions, might be immunosuppression.