Two murine monoclonal antibodies to peripheral blood monocyte differentiation antigens discriminate within M5 acute non‐lymphoid leukemia (ANLL) cells

Abstract

Two murine monoclonal antibodies (MoAbs), LAM3 and LAM7 of the IgG1 isotype, which were produced by immunization with normal peripheral blood monocytes (PBM), were assayed in their specificity by indirect immunofluorescence against a panel of normal as well as leukemic cells. Both LAM3 and LAM7 were reactive with PBM while LAM3 also recognized platelets. Neither MoAb showed reactivity with erythrocytes, granulocytes, or resting and mitogen activated B and T lymphocytes. The reactivity with bone marrow cells correlated with the degree of monocyte contamination. Among the 62 cases of leukemia tested, which included three cases of B-CLL, 19 cases of ALL, and 40 cases of ANLL, both MoAbs reacted highly homogenously only with M5b ANLL cells. These findings indicate that the two MoAbs, which recognize two distinct epitopes, represent useful markers in the differential diagnosis of M5b ANLL.

Immunological definition of acute promyelocyte leukemia (FAB M3): A study of 39 cases

“…Krause, in a report of 6 in M3-hypergranular cases while is statistically higher in M3-hypogranular cases (16).…”

“…Monoclonal antibodies (mAb): the panel of mAb selected for testing ANLL included: OKB2 (CD24) by Ortho Pharmaceutical Raritan, NJ, USA; Leu 1 (CD5), Leu 2a (CD8), Leu 3a (CD4), Leu 4 (CD3), Leu 6 (CDla), Leu 9 (CD7), Leu 12 (CD19), anti-HLA-DR, Leu 16 (CD20), Leu 56 (CD2), by Becton Dickinson, Mountain View, CA, USA; BA 2 (CD9) by Hybritech, San Diego, CA, USA; My 7 (CD13), My 9 (CD33), Mo2 (CD14) by Coulter Immunology; anti-gp 2b/3a (CD4la) by Dakopatts, Denmark. LAM3 and LAM 7 are 2 anti-monocyte mAb whose specificity has been previously reported (6). The reactivity of mAb was determined by indirect immunofluorescence or flow cytometry (FAC-Scan ; Becton-Dickinson) of freshly prepared and unfixed cells.…”

Production and characterization of two immunotoxins specific for M5b ANLL leukaemia

“…The antigens recognized by the 2 MAbs are indeed serologically distinct; their expression is restricted to circulating monocytes (LAM7) and to monocytes and platelets (LAM3), and no significant expression has been found in bonemarrow stem cells. Their expression in M5b leukaemias is highly homogeneous (Lopez et al, 1987). Because of these serological features we have attempted the construction of two ITS by conjugating the 2 MAbs with the emitoxin SAP.…”

“…and by Lopez et al (1987). MAbs were purified from ascitic NaCl linear gradient and analyzing eluted material by SDS-PAGE.…”

“…Among the new plant toxins described, Saporin 6 (SAP) emitoxin from Saponaria oficinalis (Stirpe et al, 1983) appears to be one of the most promising candidates in the construction of immunotoxins, because of the low molecule cytotoxicity and the favourable conjugate pharmacokinetics of the conjugates (Siena et al, 1988). In the present study we have produced 2 immunotoxins by conjugating the murine MAbs LAM3 and LAM7 specific for M5b leukaemias Lopez et al, 1987) to SAP, using the hetero-bifunctional reagent SPDP as linking agent. Here we describe the development of these SAP immunotoxins and the analysis of their serological and functional in vitro cytotoxic activity.…”