Evaluation of Taxol cytotoxicity on B-CLL cells in vitro

Taxol is a new antimicrotubule agent that, besides a well known efficacy against solid tumors, has shown activity in non-Hodgkin's lymphomas too. We therefore investigated its in vitro cytotoxic activity against cells from patients affected by chronic lymphocytic leukemia (CLL). Peripheral blood lymphocytes from 46 CLL patients were incubated for four days with Taxol at doses ranging from 0.01 to 10 mM and the cytotoxicity was evaluated by a colorimetric method (XTT). In most samples Taxol was inactive and the IC50 was > 10 mM in 40 out of 46 patients. It is worthwhile noting that four of the six in vitro responsive patients had unfavourable clinical features. In three unresponsive patients we also observed that Taxol was not able to induce apoptosis in vitro. In conclusion, based on in vitro data, it seems that Taxol is not an active drug in standard CLL but we cannot exclude some efficacy in other more rapidly proliferating lymphoproliferative disorders.

Beta-1-integrin expression in adult acute lymphoblastic leukemia: possible relationship with the stem cell antigen CD34

In the hemopoietic system, interactions between stem cells and components of the bone marrow microenvironment play a pivotal role in blood cell proliferation and differentiation. Among the adhesion molecules, the integrins of the beta 1-subfamily are known to direct cell-cell and cell-matrix interactions and evidence has been provided that CD34-positive stem cells bind either to the bone marrow stroma or to the extracellular matrix proteins through the beta 1-integrins. It seems that changes in their expression pattern or signalling function are likely to reflect disturbances at the hemopoietic bone marrow microenvironmental level. Any alteration of their biological functions makes them attractive candidates for playing decisive roles in the leukemic processes. In this view, beta 1-integrins have been recognized to mediate those cellular interactions and migrations that are important in the biology of leukemia. In this paper we review some aspects of the role played by beta 1-integrins, especially VLA-4 and VLA-5, in adult acute lymphoblastic leukemia in relation with the expression rate of the stem cell antigen CD34.

Cutaneous vasculitis in non Hodgkin's lymphoma

Cutaneous vasculitis has been described in association with various hematological malignancies, but it seems to be very uncommon among non Hodgkin's lymphomas (NHL). For this reason no attention has been given to the peculiarity of this rare association. We identified 5 cases of cutaneous vasculitis among 315 NHL patients examined at our Institution from 1984 through 1990 and after the appearance of vasculitis, we observed some heterogeneity in either the degree of activity or in the clinical outcome of the NHL. The onset of cutaneous vasculitis appeared to mark two different clinical patterns: a vasculitis present from diagnosis characterized an indolent course of the neoplasia, while a late-appearing vasculitis was followed by rapid lymphoma progression and short survival.

Vitro drug-induced apoptosis in freshly isolated leukemic cells: a flow cytometric analysis

Fludarabine is considered a useful drug in the management of B-CLL resistant to conventional chemotherapy as it is able to trigger apoptosis in neoplastic B cells. In order to analyze this aspect, we tested by means of a simple and rapid flow cytometric method the in vitro apoptotic response of CD5+ B-CLL lymphocytes to FAMP, in comparison with other cytoreductive agents such as Interferons. Our findings showed that apoptosis occurred significantly in lymphocytes cultured with FAMP, but not with IFNs. In conclusion, flow cytometry allows an easy and rapid detection of in vitro drug-induced apoptosis, possibly representing also a reliable assay for testing tumor cell sensitivity or resistance.

CD34 expression in adult acute lymphoblastic leukemia

The expression of the pluripotent stem cell antigen CD34 was evaluated at diagnosis in forty-five adult patients with de novo ALL. Comparison of clinical and hematological features between CD34 positive (24/45) and CD34 negative (21/45) patients showed that the former were of older age, had more pronounced lymphoid organ involvement and higher serum LDH levels. Immunophenotypic analysis of marrow blast cells revealed a significant predominance of the 'null' phenotype in the CD34 positive group, together with a strong expression of the VLA-4 and VLA-5 integrins (fibronectin receptors). CD34 positive ALL were also more frequently associated with either aberrant myeloid-related antigens (CD13, CD33) or the P-gp/MDR-1 phenotype. Only 11 out of 24 (45%) CD34 positive patients achieved complete remission after induction chemotherapy, compared to 20/21 (95%) CD34 negative cases. Furthermore, survival was significantly shorter in the CD34 positive group (6.6 mo. vs 13.5 mo.). These results suggest that in ALL, as in AML, CD34 positivity may predict a poor prognosis.