Kx antigen, the McLeod phenotype, and chronic granulomatous disease: further studies.

Leukocytes of nine unrelated boys with X-linked chronic granulomatous disease lack Kx antigen. In three of these cases, the red cells also lack Kx and have the McLeod phenotype and abnormal morphology. X-linked chronic granulomatous disease CGD can thus be separated into two types. Type I cases have an antigenic deficiency that is restricted to the phagocytic leukocytes while in type II, the deficiency involves both leukocytes and red cells. Red cells of type II CGD patients have enhanced i antigen activity suggesting that they are under hemopoietic stress. Normal Kx synthesis is directed by an X-linked gene named X1k. Three variants, X2k, X3k, and X4k order the different permutations of leukocyte and red cell Kx antigen production that have been recognized.