Immune functions in pernicious anaemia before and during treatment with vitamin B12.

Lymphocytes and their function in patients with pernicious anaemia (PA) have been studied. E-rosette forming cells (E-RFC) and surface immunoglobulin positive (S-Ig) lymphocytes in peripheral blood, PHA responses of peripheral blood lymphocytes and tuberculin skin test (Mantoux) were studied before and during specific treatment with cyanocobalamin. First in order to test possible alterations in the metabolism of lymphocytes in PA, the effect of culture conditions was studied; the optimal conditions proved to be the same as for normal cells. The serum of PA patients as a supplement for culture medium did not differ from normal. When the patients were in remission, responses in a folate poor thymine free medium (TC 199 special) were significantly greater than those obtained using a folate rich medium (RPMI 1640) (P less than 0.01), possibly indicating activation of the salvage pathway for DNA synthesis and, therefore, increased incorporation of 125IUdR in the folate poor medium. In vitro tests did not indicate any disturbances in the functions of lymphocytes either before or during appropriate treatment as studied in 23 PA patients. However, the tuberculin skin test changed from negative to positive in 5 out of 7 cases tested.