ABSTRACT
Twenty-two patients with cancer larynx and/or hypopharynx were subjected to surgery. The effect of sera, taken from the patients and control individuals, on normal lymphocytes was assessed in the presence of non specific stimulant [PHA] and tumour antigen as speciuc stimulant. Higher proliferation of lymphocytes was noticed in response to control sera, compared to cancer patients. Also, a significant increase in lymphocyte biastogenesis in response to PHA and T.A. was noticed postoperatively. Patients with cancer larynx and/or hypopharynx have blocking serum factors in their sera which cause reduction in response of normal lymphocytes. These serum factors were significantly decreased or almost disappeared after one and half months postoperatively