RESUMO
Homozygous sickle cell disease patients have an increased risk of developing severe infections, probably because of impaired immunity. Cellular immunity was studied in thirty-two patients with S homozygous haemoglobin (SS) and compared to 32 A homozygous haemoglobin (AA) healthy subjects. A leukocytosis was observed but with a significant diminution of T4 and T8 proportions in sickle cell patients. B lymphocytes, concanavalin A, phytohaemagglutinin, and phorbol myristate acetate-induced lymphocyte proliferation were not different between the two groups except for enhanced pokeweed mitogen stimulation in SS patients. In contrast, addition of autologous sera to mitogen-induced cultures resulted in a potentiation of lymphocyte proliferation significantly greater in patients with S homozygous haemoglobin when compared to subjects with A homozygous haemoglobin. This highly amplified mitogen-induced response of lymphocytes by SS autologous sera, when compared to AA autologous sera, was not observed when these sera were added to lymphocytes obtained from an allogenic healthy individual. In vivo interleukin 2 production and natural killer activity were not different between SS and AA individuals. We conclude that there are functional abnormalities of cell-mediated immunity in patients with sickle cell anaemia and the SS lymphocyte activation by autologous sera was probably due to infectious and drepanocytic antigenic determinants contained in SS serum.
