The functions of human monocytes in normal subjects and in disorders associated with immune deficiency

Human peripheral blood monocytes were tested for various functions. It was found that 63--70% of monocytes from 12 normal subjects phagocytized either Staphylococcus epidermidis or latex particles; 28% of Staphylococcus organisms exposed to cells were phagocytized in 1 h and 67% were killed within 2 h; 59% of phagocytizing cells reduced NBT; 77% of endocytosed rabbit gammaglobulin was catabolized in 18 h. In Hodgkin's disease, sarcoidosis and severe pulmonary tuberculosis, phagocytic and bactericidal capacity was decreased in one third to two thirds of cases, while catabolism of gammaglobulin was reduced less often and metabolism was practically unmodified. By contrast, phagocytic and bactericidal capacity were practically normal in the common variable form of agammaglobulinemia, while gammaglobulin was catabolized at a low level in all cases. There was no relationship between the functional disorders of monocytes and alterations of lymphocyte stimulation. These results indicate that mononuclear phagocytes may have intrinsic alterations of functions which can result in deficient defense mechanisms and/or immune response.