Identification and Characterization of a Functional Receptor for Interferon-y on a Megakaryocytic Cell Line

We have previously shown that human interferon-y (HuIFNy) induces platelets to become efficient effector cells, capable of killing young larvae of the parasite Schistosoma mansoni. Recently, binding sites for IFN-y on platelets have been characterized. We show here the presence of highaffinity receptors for IFN-y on the surface of the human megakaryocytic Dami cell line. Scatchard analysis indicated the presence of about 11,OOO binding sites per cell, with a kd of 3 -r0.5 x lo-'' mol/L; the apparent molecular weight of the receptor was 90 Kd. Receptor-bound '=I Hu-recombinant IFNy was rapidly internalized and degraded when the temper-