Ariane Michel

Diagnostic and prognostic significance of myelomonocytic cell surface antigens in acute myeloid leukaemia

Thirty‐six cases of acute myeloid leukaemia (AML) were tested with a large battery of monoclonal antibodies (moAbs) detecting surface markers normally expressed by myelomonocytic, T and B lymphoid, megakaryocytic and erythroid lineages. Differences in antigenic expression were observed among the various FAB subgroups: HLA‐class II molecules were found in almost all AML cases but not in the promyelocytic subgroup (M3); CD14 and CD36 antigens were detected in monocytic leukaemias (M4 and M5); the CD34 moAb (MY10) recognizing an epitope described on myeloid stem cells was positive in 88% of the M1 and 80% of the M3 cases. By a multivariate analysis, only the CD14b (MY4) discriminated significantly between M1–M2 and M4–M5 subgroups. Using Coxs model to assess the prognostic importance of variables including immunophenotyping on survival, we undertook a one by one analysis and found that the presence of CD17 antigen predicted for a shorter survival (P= 0.03). In addition this marker appeared more significant than other clinical and biological parameters.

Proposals for a Phenotypic Classification of B-Chronic Lymphocytic Leukemia, Relationship with Prognostic Factors

Immunophenotypic analysis was performed in 53 cases of B chronic lymphocytic leukemia using a large panel of monoclonal antibodies recognizing B, T, activation and myeloid antigens. Our results showed four patterns of reactivity: (a) several molecules were constantly expressed: CD19, CD20, CD24, CD37, HLA-DR, mu heavy chain, CD5, CD23, B5, CD32; (b) one antigen, CD11b, was found in 50 to 80% of the cases; (c) some markers were detected in less than 50% of the cases: CD25, CD38, CD71, CD11a, c, CD14b-c; (d) CD2 and CD16 were never detected. From these results, a phenotypic classification in three groups has been proposed and these groups were correlated with the progression of the disease, mainly with the lymphocyte doubling time of less than one year. We hypothesized that the leukemia cells could be at various stages of differentiation and/or activation according to their expression of activation and myeloid markers.

Protein tyrosine kinases in activation signal of human basophils through the immunoglobulin E receptor type I

Human basophils activated through high‐affinity immunoglobulin E (IgE) receptors (FcRI) are involved in the late phase of the allergic reaction. To investigate the possible involvement of protein‐tyrosine kinases in this activation we used human acute basophilic leukemia (ABL) cells in culture as well as a pure population of normal basophils in vitro‐derived from human bone marrow precursor cells (HBMB). ABL cells were 50–80% basophils at various stages of maturation as assessed by staining, morphology, ultrastructure, and flow cytometry analysis, and only basophils in ABL cells expressed FcRI. Aggregation of FcRI by IgE and anti‐IgE, IgE and antigen, or anti‐FcRI monoclonal antibodies on ABL cells or on HBMB, led to increased tyrosine phosphorylation of 120‐, 100‐, 80‐, 72‐, 50‐ to 65‐, and 38‐kDa substrates. Tyrosine phosphorylations in ABL cells were in basophils because 1) they were detected after a 5‐s stimulation, 2) they were observed under conditions where mediator release is minimal, i.e., in the absence of extracellular calcium, 3) hapten addition during antigen stimulation resulted in almost total disappearance of tyrosine phosphorylations within 30 s. There was correlation between histamine release and tyrosine phosphorylation in anti‐IgE dose‐responses and in dose‐responses of the tyrosine kinase inhibitor genistein. The tyrosine kinase p72 syk was detected in the cells. Stimulation of ABL cells for 1 min resulted in extracellular calcium‐independent tyrosine phosphorylation and activation of p72 syk Therefore, tyrosine kinases are involved in the early steps of human FcRI signaling in basophils. Tyrosine kinases and their substrates could represent new potential therapeutic targets to prevent the development of the allergic reaction. 1996.

CD1 expression on B-CLL lymphocytes

Summary In a previous report we showed that D47 CD1a monoclonal antibody positively labelled B‐CLL cells of some patients. Six cases were selected to further characterize CD1 antigenic expression at the leukaemic cell surface using flow cytometry with a battery of six CD1a, two CD1b and two CD1c monoclonal antibodies. CLL cells were positively labelled with CD1a antibodies except OKT6 and NA1/34: in all cases they were CD1b negative and CD1c positive. These results suggested that CD1a, c epitopes can be detected on leukaemic B cells in addition to other T cell differentiation antigens. In view of recently published data demonstrating the presence of CD1c molecule in normal B cell subsets, our results further question the relationship of B‐CLL with a restricted subpopulation of B cells.

Interleukin 4 inhibits the proliferation and promotes the maturation of human leukemic early B cells

Abstract:  The effects of interleukin 4 (IL‐4) on human leukemic precursor B‐cell lines were investigated. Recombinant IL‐4 (rIL‐4) was added to three acute lymphoblastic leukemia‐derived pre B‐cell lines: Reh, Km3 and Nalm‐6. Our results show that rIL‐4 significantly decreases continuous proliferation of Reh and Km3 cells while Nalm‐6 cells have a limited response in this respect. This rIL‐4 effect is dose‐dependent and can be neutralized by anti‐IL‐4 monoclonal antibody (mAb). Furthermore, rIL‐4 down‐regulated IL‐3‐induced proliferation of Reh cells. Phenotypic analysis of rIL‐4‐treated cells points to significant induction of surface marker maturation of leukemic cells by this cytokine. Together, these in vitro data suggest that IL‐4: 1) inhibits the proliferation and 2) promotes the differentiation of certain human leukemic B‐cell precursors.

CD 1 c is not a feature of mixed‐cell type but of a typical form of chronic lymphocytic leukaemia

To the editor: In a recent issue of the journal, A. Orazi et al. (1) described, in typical CLL, the lack of CDlc molecule expression as studied by immuno-cytochemical labelling (Avidin Biotin Complex). The authors indicated that their results were in discrepancy with our publication (2) and with their previous report (3). Indeed, we showed that 40% of CLL samples expressed CDlc molecule as detected by flow cytometry. In a previous study, we reported for the first time that CD lc molecule and some epitopes of CD l a molecule could be expressed at the CLL cell surface; in addition we observed a strong correlation between the expression of CDlc and the severity of the disease (stage C in the Binet’s classification) (4). Furthermore, these data were emphasized in a series of 53 CLL blood samples studies with a large battery of monoclonal antibodies (mAb); we observed that the CD lc mAb labelled 36 % of the cases with a mean of positive cells at 21 24% ((5) and Fig. 1). Together, these results indicate that CD lc could be expressed in various CLL stages including typical forms of the disease.