The frequency of granulocyte-specific antibodies in postpartum sera and a family study of the 6B antigen.

We examined sera from 2313 postpartum women as a potential source of granulocyte specific antibodies. Lymphocyte cytotoxic (LC) antibodies were detected in 397 (17.2%) specimens and granulocyte agglutinating (GA) antibodies in 291 (12.6%). Only two GA positive sera had reactivity for previously defined granulocyte specific antigens (one NA1 and NB1 ). One additional serum had GA reactivity similar to a serum previously reported by van Rood and called anti-6B. The frequency of granulocyte specific antibodies (0.1 percent) in our study indicates that the productivity of random screening of parous sera for granulocyte specific antibodies is low. A four-generation family study of the 6B antigen demonstrated a parallel association between HLA-B7 and B40 and 6B reactivity in the LC, GA, and granulocyte immunofluorescence (GIF) assay. This illustrates that the granulocyte reactivity of anti-6B is not granulocyte specific but is HLA related. This report provides additional evidence that HLA antibodies such as anti-B7 (6B) can react with granulocytes bearing these antigens in the GA and GIF assays currently used to identify granulocyte specific antibodies.