Monocyte‐Macrophage Modulation of T‐lymphocyte‐Derived Colony‐Stimulating Activity Elaboration in Man

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Abstract
To investigate the source and the mechanisms of synergistically enhanced colony‐stimulating activity elaboration by the coincubated monocyte‐macrophages and T lymphocytes, we simultaneously prepared conditioned media both from the coincubated monocyte‐macrophages and T lymphocytes (ratio 1:3) in the presence of phytohemagglutinin (1%) or methanol extraction residue of bacillus Calmette‐Guerin (50 μg/ml) and from the isolated T lymphocytes that had been primed with monocyte‐macrophages in the presence or absence of phytohemagglutinin or methanol extraction residue of bacillus Calmette‐Guerin. Subsequently, colony‐stimulating activity in various conditioned media was assayed using light‐density (< 1.070 g/ml), nonadherent normal human marrow cells. Live monocyte‐macrophages synergized with and significantly (P < 0.01) agumented the T lymphocyte‐derived colony‐stimulating activity elaboration; while killed monocytes‐macrophages had no such effect. Similarly, actinomycin D and cycloheximide not only diminished monocyte‐macrophage colony‐stimulating activity elaboration but also reduced their synergistic interaction with T lymphocytes and their ability to augment the T lymphocyte‐derived colony‐stimulating activity elaboration. In contrast, mitomycin C failed to diminish both ‐ monocyte‐macrophages' ability to synergise with T lymphocytes and also to augment T lymphocyte‐derived colony‐stimulating activity. These data suggest that monocyte‐macrophages require an intact transcriptional and translational processes, but not DNA synthesis for synergising with T lymphocytes or for augmenting T lymphocyte colony‐stimulating activity elaboration.