LYMPHOCYTE SUBSET ANALYSIS AND GLYCOSYLPHOSPHATIDYLINOSITOL PHENOTYPEIN PATIENTS WITH PAROXYSMAL-NOCTURNAL HEMOGLOBINURIA

Using multicolor flow-cytometry we have examined 19 patients with paro xysmal nocturnal hemoglobinuria (PNH) (18 with active disease and 1 sp ontaneous remitter) to determine absolute numbers of lymphocyte subset s and the proportion of glycosylphosphatidylinositol (GPI)-deficient c lones amongst these subpopulations. Lymphocyte subsets were abnormal i n all patients; the most frequent findings were low absolute numbers o f natural killer (NK) cells (median, 0.08 x 10(9)/L; normal range, 0.2 to 0.4 x 10(9)/L) and low absolute numbers of B cells (median, 0.05 x 10(9)/L; normal range, 0.06 to 0.65 x 10(9)/L). GPI-deficient B, T, a nd NK cells were identified in 88%, 84%, and 89% of patients, respecti vely. The proportion of GPI-deficient cells within individual lymphoid lineages was highly variable, though in most patients the percentage of GPI-deficient NK cells was considerably higher than B or T cells. T hese observations can be explained when mechanisms of normal lymphopoi esis are considered. Despite these quantitative and qualitative abnorm alities, no patients suffered an excessive number or severity of infec tions. The detection of PNH clones amongst all lymphocyte lineages may provide important information regarding the natural history of the di sease and additional insights into kinetics of adult lymphopoiesis. (C ) 1998 by The American Society of Hematology.