The immunochemical characteristics of granulocyte alio- and autoantibodies can easily be studied with indirect immunofluorescence techniques. The correlation of these properties with the serological behavior of the antibodies and the clinical condition in which they were found was studied. The investigations included the determination of immunoglobulin class, subclass, light-chain composition, as well as optimal temperature of activity. Complement fixation in vitro was also investigated. Striking differences were found between IgG and IgM antibodies in their serological properties, especially in the granulocytotoxicity and leukoagglutination tests at different temperatures. Differences in light-chain and IgG subclass compositions of the antibodies did not seem to play a role. In studying the distribution of granulocyte-specific antigens on normal granulocytes and granulocytes in all stages of development, it was found that, while NAl5 NA2 and ND! are present in the same quantity on the cells of an individual, the NBt antigen is unequally distributed, both over ripe granulocytes and granulocyte precursors.

A family is presented, in which the mother developed strong neutrophil granulocyte-specific antibodies with the specificity anti-NA(1). The first and third children, both NA(1)-positive, suffered from severe transient neonatal neutropenia, but the second child, NA(1)-negative, did not. Anti-NA(1) antibodies were detectable in the serum of one affected child and the antibody level was directly related to the extent of neutropenia. The incidence of granulocyte-specific antibodies in 198 pregnant women was determined and found to be low.