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On fresh leukemic cells taken from 30 patients with acute promyelocytic leukemia (APL) the membrane expression of a series of adhesion molecules including beta 2 integrins (CD11a/LFA-1, CD11b/Mac-1), selectin ligands (CD15/Le(x), CD15s/Le(x)) and tyrosine-phosphatase isoforms (CD45RA, CD45R0) was analyzed. The expression of these molecules was also studied in nine of these patients following the APL cells' culture with and without all-trans retinoic acid (ATRA). The fresh APL promyelocytes expressed CD45RA and CD15s on their surface, while CD11a, CD11b, CD15, and CD45R0 were constantly absent. In vitro treatment with ATRA consistently increased the expression of CD15, CD11b, and CD45R0 on leukemic promyelocytes; these changes were paralleled by a decrease of CD45RA display. The expression of sialylated antigen CD15s was fully independent from CD15 suggesting a differential enzymatic regulation within this selectin ligand system. ATRA was, however, incapable of promoting the up-regulation of CD11a in APL. As a result, asynchronous phenotype (CD11a-, CD11b+, CD15+, CD15s+/-, CD45RA-, CD45R0+) was generated that is normally undetectable on maturing myeloid cells. In order to provide a further control a case of acute agranulocytosis was also investigated, in which > 75% bone marrow cells were arrested at the promyelocyte stage; these bone marrow cells showed a surface phenotype identical to non-leukemic promyelocytes (CD11a+, CD11b+, CD15+, CD45R0+, CD45RA-) with a spontaneous ability to differentiate in vivo towards the more mature stages of myeloid differentiation. We therefore suggest that in fresh and ATRA-induced APL cells distinct, regular phenotypic changes are identifiable that are probably associated with t(15;17) and not seen in normal and activated bone marrow.

In the present study we investigated the membrane expression of selectin ligands (CD15/Le(x), CDw65/VIM2, CD15s/sLe(x), beta 2 integrins (CD11a/LFA-1, CD11b/Mac-1) and CD45 phosphatase isoforms (CD45RA, CD45O) on leukaemic cells from 28 patients with acute myeloid malignancies cultured with and without all-trans retinoic acid (ATRA). Within each adhesion system. ATRA was able to differentially regulate distinct molecules. Furthermore, it was able to exert effects specific for acute promyelocytic leukaemia (APL) blast cells, as well as to induce a series of non-cytotype-restricted phenotypic changes. An impressive feature of ATRA induction was a simultaneous increase in the expression of CD15, CDw65 and CD11b on leukaemic promyelocytes. The sialylated antigen CD15s, however, showed results independent from the other two carbohydrates (CD15 and CDw65), suggesting a differential enzymatic regulation within the selectin ligands system. In spite of the well-recognized expression of CD11a throughout all stages of normal myeloid differentiation, APL blast cells were found to virtually lack LFA-1 expression. Moreover, ATRA was unable to promote an up-regulation of this antigen in APL, while inducing a frequent down-modulation in non-APL cases constitutively expressing this antigen. In APL cases ATRA generated an asynchronous phenotype (CD15+, CDw65+, CD11b+, CD11a-), undetectable on normally maturing myeloid cells, but consistent with the concept that incomplete differentiation, in terms of surface molecule expression, can be sufficient to obtain therapeutic results.

In 8 patients (age 25 +/- 46 years, mean 34.5), 4 with Hodgkin's disease (HD) and 4 with non-Hodgkin's lymphoma (NHL), circulating stem cells (CSC) collected at the time of rapid leukocyte and platelet recovery after intense chemotherapy were employed for autologous hematological reconstitution after very-high-dose chemotherapy (CVB combination). At the time of graft 2 patients were in 1st remission and 2 in 2nd, while the remaining 4 had persistence or progression of disease. Autografted patients received 3.4 +/- 8.3 (mean 5.2) x 10e8/Kg mononuclear cells and 2.1 +/- 40.5 (mean 22.5) x 10e4/Kg CFU-GM. All patients had prompt and sustained engraftment, though in one case platelets never reached normal levels. Recovery time was respectively 10 +/- 17 days (mean 13.2) for granulocytes 0.5 x 10e9/L, and 10 +/- 49 days (mean 20.3) for platelets greater than 50.0 x 10e9/L, with an interval of less than 4 days from greater than 0.5 to greater than 1.0 granulocytes in 7 out of the 8 patients. All patients are currently alive at 57 +/- 645 (median 262) days, and 7 in remission at 61 +/- 645 (median 297) days from autologous blood stem cell transplantation (ABSCT). Our study demonstrates that CSC collected after mobilizing chemotherapy are able to promptly restore and sustain hemopoiesis after marrow ablative chemotherapy in patients with malignant lymphoma. CSC reduce toxicity and hospitalization so impressive, that in malignant lymphomas ABSCT could rapidly be considered for first line strategy.