USE OF CRYOPRESERVED LYMPHOCYTES FOR ASSESSMENT OF THE IMMUNOLOGICAL EFFECTS OF INTERFERON THERAPY IN RENAL-CELL CARCINOMA PATIENTS

Experiments were designed to assess whether cryopreserved PBL could be used to monitor the immunological effects of IFN-alpha therapy in ren al cell carcinoma (RCC) patients. It was found that programmed freezin g and thawing of peripheral blood lymphocytes (PBL) from normal blood donors did not substantially change lymphocyte subset proportions and that cryopreserved PBL were able to proliferate in response to IL-2. I t was also possible to activate the cytolytic activity of frozen PBL, and the frozen leukocytes did not lose their ability to secrete IFN-ga mma after PHA activation. We have used these findings to investigate t he immunological effects of IFN-alpha therapy in RCC patients. Cryopre servation of PBL samples collected from various patients over a period of 9-14 months enabled us to compare the in vitro reactivity of PBL f rom individual RCC patients repeatedly and under standard conditions, It was found that IL-2-induced proliferative responses of PBL from IFN -alpha non-responders, collected prior to IFN-alpha therapy, were sign ificantly decreased as compared to those from normal blood donors, The proliferative responses of PBL from IFN-alpha responders, collected p rior to IFN-alpha therapy, did not substantially differ from normal co ntrols. Culture of PBL from IFN-alpha responders for 3 days in IFN-alp ha-containing medium increased their lyric activity towards RCC target s, whereas no such increase was observed with non-RCC targets or using PBL from IFN-alpha non-responders or PBL from normal blood donors. En zyme-linked immunospot (ELISPOT) assays performed with cryopreserved l ymphocytes from IFN-alpha non-responding RCC patients, collected prior to IFN-alpha therapy, revealed a substantially decreased ability to s ecrete IFN-gamma, as compared to IFN-gamma, secretion of PBL from IFN- alpha responders or normal blood donors.