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Chronic benign neutropenia of infancy is a disease which develops a few months after birth and which is characterized by a severe selective neutropenia, accompanied by benign but persisting infections. The cause of the disease is still unknown. The sera from 5 such patients were tested for the presence of granulocyte antibodies as a possible cause of the disease. For the detection of these antibodies immunofluorescence, agglutination and granulocytotoxicity were used. All sera contained antibodies which reacted both with the neutrophils of one or both parents of the patient and a part of a panel of unrelated donors. From the reaction patterns against the panel we could identify the specificity of three sera. Two sera were directed to the neutrophil-specific antigen NA2, and the third one reacted with a hitherto not yet recognized neutrophil-specific alloantigen which we called NE1. In 4 patients we could confirm the autoimmune character of the disease by demonstrating the antibody on the patients’ own granulocytes. These results suggest that autoimmunity may be the cause of many cases of benign infantile neutropenia.

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The sera of three children with chronic benign neutropenia, due to anti-neutrophil antibodies, were studied with respect to their antibody specificity. This was done by screening the sera against a panel of leukocyte donors in the EDTA microagglutination test and in the indirect fluorescence test. Two of the sera contained antibodies against the known neutrophilspecific antigen NA2. The third serum was directed against a new neutrophilspecific antigen. Genetic analysis showed no correlation between this antigen and the already known neutrophil-specific antigens: 9A, NA1, NA2, NB1, and NC1. In the Dutch population the frequency of the new antigen, tentatively called N E I , is 23%, which gives a gene frequency of 0.12.

Summary and conclusionsDiminished survival of transfused platelets occurred in two patients given co-trimoxazole, and a third patient taking this drug developed thrombocytopenia. By means of an indirect immunofluorescence assay antibodies against donor platelets coated with co-trimoxazole were found in the sera in all cases. These antibodies were directed against the trimethoprim component of cotrimoxazole and not against sulphamethoxazole.Co-trimoxazole is a potent antimicrobial agent and is advocated for treatment and prophylaxis in leukaemia. Hence its adverse effect on platelets is of great importance.