Abstract
We have investigated the presence or absence of the red cell Kx antigen on human granulocytes by measuring specific uptake of anti-Kx using three techniques: direct measurement by 125I-staphylococcal protein A (125I-SPA) and avidin-biotin-complex (ABC) immunoperoxidase staining and also, an indirect measurement using granulocyte adsorption of anti-Kx. Our results with all three methods indicate that the Kx antigen is not present on normal human granulocytes. Prior to adsorption of the anti-Kx serum with purified, pooled, normal human granulocytes, 11 of 21 (53%) of normal granulocytes were non-reactive by 125I-SPA and 16 of 20 (80%) by ABC. This pattern of reactivity was shown to be due to contamination of our anti-Kx serum with an antibody to a granulocyte-specific antigen unrelated to the Kx antigen. After adsorption, there was no diminution in the reactivity of the adsorbed anti-Kx compared to the unadsorbed antiserum against red cells which express strong Kx antigen, i.e. Ko and DTT-modified normal human red cells, by either serologic or 125I-SPA techniques. Likewise, reactivity with McLeod red cells, which have weak expression of the Kx antigen, was not changed using either the unadsorbed or adsorbed anti-Kx. The adsorbed anti-Kx was nonreactive with all 12 normal donors' granulocytes tested by 125I-SPA and with 10 normal donors' granulocytes tested by ABC. Furthermore, granulocytes from a Ko individual were nonreactive using either unadsorbed or adsorbed anti-Kx. These studies indicate that Kx antigen is not present on normal human granulocytes. Further, additional adsorption studies using granulocytes from a boy with X-linked chronic granulomatous disease (CGD) indicated that these granulocytes also do not possess the Kx antigen. In contrast to previous reports, these data suggest that Kx antigen is most probably a red cell-specific antigen and that the red cell Kx antigen has no direct relationship to the biochemical defect in CGD.
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