Characterization of neutrophil agglutinins in primary autoimmune neutropenia of early childhood.

Neutrophil agglutinins that caused primary autoimmune neutropenia in six young children less than two years of age reported earlier were investigated further for antibody identification and specificity using granulocyte agglutination technique. Initially, the patient sera were tested with parental neutrophils and further confirmed with several donor cells. The sera were tested with autologous neutrophils after partial or complete recovery of the patients from neutropenia. The pattern of reactivity of the patient sera with parental, donor, or autologous neutrophils was compared with that of standard neutrophil typing sera currently available for the antigens NA1, NA2, NB1, NC1, and 9A. The specificity was confirmed by absorbing and retesting the sera with appropriate antigen positive and negative donor neutrophils. Our data revealed anti-NA1 specificity in four and anti-NA2 in two sera. Our observations together with that of McCullough et al suggest that NA1 and NA2 antigens are frequently associated with primary AINI in young children as compared to other neutrophil antigens.