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-ac tivated 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 epsil on(-), CD4(-), CD8(-) and express mRNA of zeta chain) suppressed LPS-i nduced 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 immu nosuppressive effect of BC-1.10 is due to an elimination of B lymphobl asts, and that one of the physiological functions of lymphokine-activa ted killer (LAK) cells, which are induced as a consequence of immune r eactions, might be immunosuppression.