Rh mosaicism and aberrant MNSs antigen expression in a patient with chronic myelogenous leukemia

This is, to our knowledge, the first report of combined Rh and MNSs antigen alteration in a leukemic patient. Red blood cells of a chronic myelogenous leukemia patient demonstrated mixed field reactions with anti-Rh(o) (D) reagents in August 1980. Earlier tests indicated he was Rh(o) (D) positive in 1967, but Rh(o) (D) and D(u) negative from 1973 to 1980. Titration studies with anti-hr'' (c) and anti-hr'' (e) indicated depressed expression, and there was also very weak s expression. One hundred per cent of cells studied from 1967 to 1980 were Philadelphia chromosome (Ph1) positive. No abnormalities in chromosomes associated with the Rh or MNSs blood groups 1 and 4, respectively, were noted. Phenotypes from August 1980 through September 1981 revealed normalization of red blood cell antigen status with an increase of Rh(o) (D) positive cells from 35% to 100%. Chromosomal studies in October, 1980 and June, 1981 revealed Ph1 mosaicism with 25 and 75% Ph1 negative cells, respectively. These findings suggest that normalization of previously altered red blood cell antigen expression may reflect resurgence of normal stem cell lines.