Impaired phytohaemagglutinin-induced cytotoxicity in vitro of lymphocytes from patients with Hodgkin's disease or chronic lymphatic leukaemia

Abstract

Lymphocytes from healthy, unsensitized donors damage allogeneic tissue culture target cells in the presence of phytohaemagglutinin (PHA). In this investigation, blood lymphocytes from eleven patients with clinically active Hodgkin's disease and from eight patients with chronic lymphatic leukaemia (CLL) were tested in vitro for PHA-induced cytotoxicity to Chang cells. Blastoid transformation and DNA-synthesis in the presence of PHA were studied in parallel experiments. The cytotoxicity of the patients' lymphocytes was significantly lower than that of lymphocytes from healthy donors. Synthesis of DNA and blastoid transformation was subnormal in all cases of CLL and in most cases with Hodgkin's disease. A good correlation between cytotoxicity and stimulation by PHA was observed in most cases.

The incidence of positive skin reactions to tuberculin was high in the CLL-group and low in the Hodgkin group. If it is assumed that the pool of immunologically competent cells was normal in the CLL-patients, this would account for their intact cellular reactivity in vivo. In contrast, the high proportion of leukaemic cells could be expected to mask the reactivity of the normal CLL-lymphocytes in vitro. The weak in vitro reactivity of the lymphocytes in Hodgkin's disease is in line with the view that deficient lymphocytes are present in this disease and suggests that the patients' pool of immunologically competent cells is reduced. This could also contribute to the anergic state seen in these patients.