Phagocytosis of immune complexes by polymorphonuclear leucocytes in patients with Felty's syndrome.

The possible role of phagocytosis of circulating immune complexes by neutrophils in the production of the neutropenia of Felty's syndrome has been investigated. Normal neutrophils phagocytosed massive inclusions from the sera from twelve of fifteen patients with Felty's syndrome when incubated with these sera. Such inclusions were phagocytosed from only three of fifteen patients with seropositive RA who did not have Felty's syndrome. Normal neutrophils were more effective than patient neutrophils with regard to phagocytosis of inclusions from the patients' serum suggesting a defect in phagocytic function of Felty's neutrophils. The titre of granulocyte-reactive antinuclear antibodies did not appear to be related to the degree of neutropenia. The data suggest that phagocytosis of circulating immune complexes by neutrophils may interfere with the function of these cells in combating infection and also render them susceptible to removal from the circulation thus leading to the development of neutropenia.