A sensitive method for immunophenotyping stored leukemia and lymphoma cells with preservation of morphological detail

Oncofetal antigen in Xiphophorus detected by monoclonal antibodies directed against melanoma-associated antigens

Monoclonal antibodies (MAbs) directed against Xiphophorus melanoma cells were developed and tested by indirect immunofluorescence and immunoperoxidase staining for reactivity with a panel of 15 allogeneic tissues and 12 allogeneic cell lines. The reactivity of such MAbs was restricted to melanoma cells from tumor biopsies and melanoma-derived cell lines. In addition, all embryonic cells of all histiotypes from developmental stages later than mid-organogenesis and from corresponding short term in vitro cultures reacted with these MAbs. In contrast, normal tissues and organs from adult fish displayed no reactivity, thus implying that the melanoma-associated antigens detected by the MAbs described are oncofetal antigens.

Establishment and characterization of a permanent human IgA2/kappa myeloma cell line

A human myeloma cell line designated LOPRA-1 has been established from ascites fluid containing malignant plasma cells of a patient with IgA2/kappa multiple myeloma. The cultured cells which are Epstein-Barr virus (EBV) negative have retained the morphological, cytochemical, ultrastructural and immunophenotypical features of well-differentiated plasma cells. They express the plasma cell antigen PCA-1, the antigens CD28 (Kolt-2) and CD38 (OKT10), the transferrin-receptor (OKT9), and some epitopes of the CD24 antigen (HB8, VIB E3), but are negative for surface immunoglobulins. HLA class II antigens (HLA-DP, -DQ, -DR) and other B-cell markers such as CD10 (CALLA), CD19 (B4), CD20 (B1), CD21 (B2), CD22 (HD39), CD23 (MHM6), CD37 (BL14) and CD39 (G28-8) as analysed by both flow cytometry and immunocytochemistry (PAP/APAAP). With respect to immunoglobulin synthesis, two stable clones were selected by single cell cloning: clone LOPRA-1/5 synthesizes large amounts of alpha 2 heavy and kappa light chains, but secretes only small amounts of these molecules, whereas clone LOPRA-1/4 is clearly devoid of intracellular immunoglobulin heavy and light chains and thus appears to be a chain loss variant. Cytogenetic analysis revealed a pseudotriploid phenotype with several structurally abnormal marker chromosomes: 3n + -, 70, XX, -X, -1, -4, -6, -8, -8, -13, -16, +7, +18, +21, +i(1q), +i(1q), +6q-, +3mar.

Comparison of immunofluorescence and immunoperoxidase techniques for demonstration of phenotype and monoclonality in lymphoproliferative disorders

To determine whether a simple immunoperoxidase (IP) technique could replace the traditional immunofluorescence (IF) technique (by fluorescence microscopy) for determination of phenotype and monoclonality in cell suspensions from patients with lymphoproliferative disorders, we tested samples from 48 cases by both methods, using small panels of antibodies designed to determine proportions of B-cells, T-cells and cells bearing immunoglobulin light chains. There were 27 cases of chronic lymphocytic leukaemia (CLL), 6 of prolymphocytic leukaemia (ProLL), and 15 of non-Hodgkin's lymphoma (NHL). We found that IP was at least as reliable as IF in all cases. In the 47 B-cell cases, the mean proportion of cells apparently belonging to the malignant clone was higher by IP than by IF; conversely, the proportion of B-cells displaying the non-malignant light chain marker and the proportion of residual T-cells was apparently lower by IP. We conclude that IP is a useful and reliable technique for determining phenotype and monoclonality in lymphoproliferative disorders; because it is tolerant of delays to samples in transit and requires only simple facilities, it may be particularly suitable for small laboratories.

Characterization of a human B-lymphocyte carcinoma cross-reacting antigen (BLCa) in B lymphocytes identified by two murine monoclonal antibodies

The murine monoclonal antibody (MAb) MA6 is selectively reactive against a large variety of human B lymphocytes including those in early stages of B-cell differentiation such as committed progenitors of B lymphocytes, pre-B lymphocytes, Burkitt lymphoma cells, and those at later stages of differentiation such as peripheral blood B lymphocytes and myeloma cells. The major antigen identified by this antibody on such B lymphocytes (BLCa) is a 55-kDa glycoprotein or a group of similar glycoproteins, with the MA6-reactive determinant localized on the carbohydrate moiety. On isoelectric focusing, this antigen exhibits a degree of charge microheterogeneity, migrating as a diffused band with an average isoelectric point at pH 5.7. BLCa was also identified by another murine MAb, MA5. The antigenic determinant recognized by this antibody is also localized on the carbohydrate moiety of the molecule, but, unlike the MA6-reactive determinant, it is shared by other glycoproteins from different types of cells.

Detection of a multidrug resistant phenotype in acute non-lymphoblastic leukaemia

Most adult patients with acute non-lymphoblastic leukaemia (ANLL) relapse with drug resistance. Overexpression of a plasma membrane protein, P-glycoprotein, correlates with multidrug resistance in human and animal cell lines. We have detected a multidrug resistance phenotype in two patients with drug resistant ANLL by an immunocytochemical assay using a monoclonal antibody to P-glycoprotein. Sequential analysis of peripheral blood samples from both patients showed a progressive increase in both the intensity of staining and the proportion of leukaemic cells that bound antibody as the disease progressed. The assay is simple, and may have prognostic and therapeutic implications.

A rapid, simple method for leukemia immunophenotyping using air-dried blood and bone marrow smears

This paper describes a modification of the peroxidase technique by which immunophenotyping may be carried out on routinely air-dried blood and bone marrow (BM) smears. The method is simple and quick, requires no special equipment, can be performed on fresh or stored specimens and gives a standard of morphological detail equal to that of routine blood films. With a monoclonal anti-HLA-DR antibody as a prototype, it was possible to demonstrate reliably, the presence of positively and negatively stained cells of appropriate morphological types in the peripheral blood of leukemia patients. Although only about one-third of antibodies tested were effective with the technique, we identified monoclonal antibodies capable of demonstrating myelomonocyte, granulocyte, monocyte, pan-leukocyte, transferrin, platelet, pan-T, 'cALLA plus B cell' and other antigens. However, we have not yet found antibodies able to identify T cell subsets, nor to distinguish 'common' acute lymphoblastic leukemia from its rare B-cell counterpart. With these limitations the method is suitable for routine use alongside cytochemistry in the differential diagnosis of leukemias and lymphomas.