Target-effector interaction in the natural killer (NK) cell system. VI. The influence of age and genotype on NK binding characteristics.

Four independent assays were used to compare target-cell binding by NK cells in different populations. First, detergent solubilized and reduced proteins from the surface of Moloney lymphoma cells (YAC) were electrophoresed in SDS-polyacrylamide gels. The glycoproteins recognized by NK cells (NK-TS) were eluted from the gels and used in semi-quantitative absorption studies or were used to inhibit the formation of target-effector conjugates as an estimate of relative avidity. These findings were supported by a comparative analysis of cold target competition curves and saturation studies in which 51Cr-labelled target cells were carefully titrated. The results suggest that NK cells 'mature' during ontogeny to higher avidity binding whereas the decline in NK function during senescence can solely be attributed to a decrease in population size. A comparison of high (CBA) and low (A/Sn) NK reactive strains revealed that in low responder (i) absolute NK frequency was decreased, (ii) relative NK-TS absorption per NK cells was low, and (iii) relative avidity of NK cells was identical to that in the high responder strain. These results suggest that the putative NK receptor to YAC may be of restricted heterogeneity.