RABBIT ANTISERA TO CELL LINES RC2a AND U937: ANTIGENS EXPRESSED ON HUMAN LEUKAEMIC CELLS OF MYELOID, MONOCYTE AND T‐LYMPHOCYTE LINEAGE

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Abstract
Rabbit antisera have been produced to an acute myelomonocytic leukaemia (AMML)-derived cell line (RC2a) and a histiocytic lymphoma derived cell line (U937) having macrophage characteristics. The antisera were screened by complement-mediated cytotoxicity and immunofluorescence (cytofluorograph analysis) against separated leukaemic (122 patients plus 13 cell lines) and normal haematologic cell populations (60 preparations from 20 donors plus 10 B-lymphoblastoid cell lines). The sera were absorbed with pooled B-lymphoblastoid cell lines including the autologous B-lymphoblastoid cell line to RC2a (CESS-B) or alternatively with B-CLL and T-CLL cells. All leukaemic cell populations were confirmed using the markers SIg, E-rosette receptor, cALL antigen, -naphthyl butyrate esterase and mydoperoxidase. Rabbit anti-RC2a (Adherent cells) (RARC2a(Ad)) and rabbit anti-U937 (RAU937) recognised antigens common to immature myeloid monocyte and T-lymphocyte lineage but did not react by cytotoxicity, absorption or cytofluorographic analysis with cells of B-lymphocyte lineage (B-lymphoblastoid or B-CLL) and reacted only occasionally with cALL patients' cells (includes pre B phenotype). These sera reacted with peripheral blood monocytes but not with other mature blood leucocytes. RAU937 reacted with a major mononuclear population from normal marrow and with more differentiated myeloid leukaemia cells. RARC2a(Ad) and RAU937 detected overlapping subgroups of myeloid leukaemia (AMoL, AMML, AML and CML) patients and Null-ALL and T-ALL patients. These subgroups are now being examined for prognostic significance.