Erythropoiesis in CML--immunomorphometric quantification, PCNA-reactivity, and influence on survival

An immunohistochemical and morphometric analysis was performed on trephine biopsy specimens in 60 patients with chronic myeloid leukemia (CML) to quantify erythropoiesis and its proliferation capacity and to assess the stainable marrow iron (hemosiderin). For this purpose, an elaborate double-immunostaining technique was applied. This included a monoclonal antibody (PC10) that is directed against proliferating cell nuclear antigen (PCNA), followed by an antibody against glycophorin C (Ret40f), to identify all nucleated erythroid precursor cells. Additionally, morphometric data were derived from immunostaining of megakaryocytes (CD61) and macrophages (PG-M1), including its hemosiderin-laden subpopulation. Finally the determination of argyrophilic (reticulin) fiber density was carried out. In comparison with a control group (15 patients) without any hematologic disorder, in CML patients morphometric evaluation showed a significant reduction in the number of erythroblasts and normoblasts. This feature was associated with a PCNA-labeling index within the normal range and a decreased stainable marrow iron (number of hemosiderin-storaging macrophages). Several parameters were established to exert a predictive value on survival. A worsening of prognosis was associated with a decrease in the number of erythroid precursors (< 460/mm2), a low hemoglobin level (< 10 g/dl), a high megakaryocyte count (> 50 cells/mm2), an increased density of reticulin fibers (> 30 i x 10(2)/mm2) and splenomegaly (> 15 cm below costal margin). Our findings are in keeping with results obtained from in vitro studies of cell proliferation in CML, which is not significantly altered in comparison with the normal bone marrow. Finally, the present data, although derived from a small group of patients, emphasize the impact of histologic variables to be included in one of the major clinical trials on prognosis in CML.