Monocyte ingestion of IgG-coated erythrocytes from haemolysing and non-haemolysing subjects.

A number of individuals in the population, including healthy blood donors and patients on methyldopa, show evidence erythrocyte coating by IgG autoantibodies (postive direct Coombs' test) without signs of a haemolytic state. The readiness with which red cells from these subjects are taken up by normal human monocytes in short term culture was examined, and compared with the phagocytosis of red cells from cases of IgG-mediated haemolytic anaemia. Red cells from non-haemolysing subjects were as avidly ingested in this system as were red cells from haemolysing patients. Similar results were obtained using normal red cells sensitised with antoantibody eluted from the cells of a healthy blood donor.