Biological effects of γ‐interferon on human tumor cells: Quantity and affinity of cell membrane receptors for γ‐IFN in relation to growth inhibition and induction of HLA‐DR expression

Abstract

A large difference in the number of γ-IFN receptors was found on a variety of human tumor cell lines with a range of 0.4 to 15 × 10³ binding sites/cell. The receptor number did not correlate with the potential responsiveness of the cells to γ-IFN, in regard to either growth inhibition or induction of HLA-DR expression, two independently regulated γ-IFN effects. However, with respect to HLA-DR expression it was found that the γ-IFN sensitivity of inducible cell lines depended on the number of receptors, so that with increasing number of receptors present on these cells lower doses of γ-IFN were required for induction of the γ-IFN effect.