STRUCTURAL SPECIFICITY OF MHC-UNRESTRICTED RECOGNITION OF HCMV-INFECTED TARGET-CELLS BY HUMAN CD56(+)NK AND LAK CELLS

Structural specificity of binding and cytolysis of HCMV-infected human foreskin fibroblasts (HFF) by human NK and LAK cells was studied in i nhibition assays. A sample of 60%-deacetylated alpha-D mannose penta-a cetate was used as inhibitor that was previously shown to specifically inhibit binding and cytolysis of tumour target cells by human NK and LAK cells. We found now that cytolysis of HCMV-infected HFF was inhibi ted in a dose-dependent manner showing complete inhibition at concentr ations above 640 nmoles/ml mannose acetate. This effect on cytolysis w as based on inhibition of conjugate formation between virus-infected c ells and CD56(+)NK and LAK cells. In the presence of mannose acetate ( 640 nmoles/ml) conjugate formation of virus-infected cells was suppres sed down to the level of uninfected cells. The latter showed residual conjugate formation on the basis of adhesive interactions with chemosp ecifity other than for mannose acetate, which were not capable of trig gering cytolytic reactions. Coculturing of target cells with LAK cells appeared to induce expression of additional mannose acetate-specific target sites yielding increases of conjugate formation and cytolysis.