MH-S, a murine alveolar macrophage cell line: morphological, cytochemical, and functional characteristics

A continuous cell line of murine alveolar macrophages (AM), designated MH-S, has been established following transformation of cells obtained by bronchoalveolar lavage from Balb/cJ mice with simian virus 40 (SV40). Thirty days after infection of the AM cultures, foci of rapidly proliferating cells were recovered and these have been propagated continuously for more than 36 mo. Following its initial isolation in Fischer's medium supplemented with L-cell-conditioned medium and horse and fetal bovine serum, the cell line is now routinely grown in RPMI-1640 medium containing 10% fetal bovine serum in the absence of conditioned medium. MH-S cells were adherent, lacked contact inhibition, and were trypsin-sensitive. They expressed intracellular T-antigen and incorporated 3H-thymidine (DNA synthesis) with a doubling time of approximately 48 h but doubled in number in 96 h. MH-S exhibited typical macrophage morphology, was greater than 98% esterase-positive, negative for peroxidase, and expressed cell surface Ia and Mac-1 antigens. The cells were Fc receptor-positive as demonstrated by rosette formation with, and phagocytosis of, antibody-coated sheep erythrocytes. Constitutive IL-1 secretion was significantly increased following stimulation of the cells with lipopolysaccharide. Like freshly isolated AM, MH-S cells suppressed the in vitro plaque-forming cell (PFC) response in a dose-dependent manner when cultured with splenic lymphocytes. This cell line should facilitate studies where homogeneous populations of AM are desirable, especially those involved in determining the immunological functions of AM and their potential role in lung pathology.