IMMUNOLOGICAL PHENOTYPE AND FUNCTION IN HUMAN BONE-MARROW, BLOOD STEM-CELLS AND UMBILICAL-CORD BLOOD

The T cell-mediated antineoplastic activity observed following allogen eic transplantation and the suggestion of improved therapeutic efficac y by autologous peripheral stem cell transplantation (PSCT) as compare d to autologous bone marrow transplantation (ABMT) for non-Hodgkin's l ymphoma (NHL) stimulated our interest in the immunologic competence of stem cell products. We report the immune phenotype and function of no rmal peripheral blood (PB) cells, bone marrow (BM) cells from normal d onors and cancer bearing patients, GM-CSF-mobilized and apheresed bloo d mononuclear cells from NHL patients, unmobilized apheresed mononucle ar cells from normal volunteers and umbilical cord blood (CB). The ana lyses include three-color fluorescent cytometry of the major hematolog ic and immunologic phenotypes as well as natural killer (NK) activity, natural suppressor (NS) activity, and phytohemagglutinin (PHA) and po keweed (PWM) mitogenesis. These studies demonstrated an increased freq uency of T cells in apheresis products as compared to BM and CB produc ts. Specifically, the mobilized PSC had significant increases in CD3(), CD4(+), CD45RO(+) and CD56(+) cells relative to BM cells. In additi on, the frequency of TCR gamma/delta(+) cells in all the stem cell pro ducts, with the exception of CB, were also increased compared to norma l peripheral blood leukocytes (PBL). However, all the stem cell produc ts had a significant depression in T (PHA mitogenesis) and B (PWM mito genesis) cell function. The depression in immune cell functionality, i n the PSC products was perhaps due to the high frequency of monocytes which appeared to be increased due to both mobilization and apheresis. The frequency of the NK cell phenotype (CD56) but not function was in creased in the mobilized PSC products, while the NK cell function in t he BM products from cancer patients but not normal donors was depresse d as compared to normal PBL. In summary, there are significant differe nces in the cellular phenotypes and immunologic competence among the v arious stem cell products with potential therapeutic implications.