MACROPHAGE-LIKE CHEMOTACTIC HYBRIDOMAS ACTIVE FOR VARIOUS CHEMOTACTIC FACTORS

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Abstract
Mouse inflammatory macrophages taken from casein-induced pleural exudates (the CANS series) and mineral oil-induced peritoneal exudates (the ONS series) of C57BL/6N (B6) mice (H-2b) were fused with BALB/c mouse (H-2d) derived myeloma cells. After selection of somatic cell hybrids, cloning and prolonged culture, two clones (CANS-196 and ONS-2C lines) strongly chemotactic to bacterial chemotactic factor and C5a were obtained. These lines also showed rosette forming abilities with sheep red blood cells (SRBC) coated with rabbit IgG anti-Forssman antibody (EA) and IgM followed by complement (EAC) and phagocytic activity, and produced lysozyme. By recloning of these clones, chemotactic subclones active for N-formylmethionyl-leucyl-phenylalanine benzyl ester (FMLP), zymosan-activated serum from AKR mice (ZAS(AKR)) and lymphocyte-derived chemotactic factor in addition to bacterial chemotactic factor and C5a, were successfully separated. Parental casein- or mineral oil-induced exudate macrophages responded to all these agents weakly, but significantly. CANS-196 and ONS-2C lines in the early period after cell fusion (8 weeks) displayed no chemotactic activity. They had high chromosome numbers (78 and 76 chromosomes, respectively) and both H-2b and H-2d antigens on their surface, confirming that these lines were hybridized cells. However, when these lines became chemotactic (28 and 20 weeks after cell fusion, respectively) they had low chromosome numbers (42-43 chromosomes) and lost the H-2b antigen, although expression of the H-2d antigen remained unchanged. At the same time, these lines newly expressed certain aged hybridoma specific cell surface antigens which were detectable by BALB/c anti-aged CANS-196 and ONS-2C cell alloantisera. Reasons for the necessity of prolonged culture for the establishment of stable macrophage-like chemotactic hybridomas, and changes in the expression of cell surface antigens are discussed in the context of chromosome loss.