[In vitro erythrophagocytosis in detecting opsonizing antibodies in a patient with Malta fever. A hypothesis on the explanation of in vivo hemophagocytosis in other patients with Malta fever].

In vitro agglutination and phagocytosis of erythrocytes by homologous neutrophil granulocytes and monocytes could be observed using the blood of a healthy person (blood group A, Rh+) to detect opsonising antibodies in the serum of a patient with Malta fever (blood group O, Rh+). Agglutination and erythrophagocytosis were independent of complement or the presence of Brucella melitensis. In patients with Malta fever and blood groups O and B, respectively, antibodies could be detected on the surface of erythrocytes of blood group A when used as antigen with the help of an immunofluorescence test. The same happened with a serum of one patient with blood group A. In vivo erythrophagocytosis detected in the bone marrow of patients with Malta fever is, therefore, possibly due to common antigens of erythrocytes of blood group A and B. melitensis.