Recognition of heterologous cells by macrophages. I. Species recognition by mouse and guinea pig macrophages in the phagocytosis of heterologous thymocytes

The ability of macrophages to recognize homologous and various heterologous cells was studied in mice, rats, and guinea pigs, in terms of the in vitro phagocytosis of non-opsonized viable thymocytes by macrophages. Mouse, rat, and guinea pig macrophages were found to phagocytize actively thymocytes from certain heterologous animals, including chickens. For instance, mouse macrophages displayed conspicuous phagocytic activities against chicken and duck thymocytes, moderate activities against guinea pig and frog thymocytes and weak activities against rat and mouse thymocytes. On the other hand, guinea pig macrophages revealed a different behaviour: they ingested only chicken thymocytes. These observations strongly suggested that mammalian macrophages possess some ability to discriminate homologous from certain heterologous thymocytes. The results, however, did not necessarily support the idea that the degree of phagocytosis is simply related to the phylogenetic distance between the animal species from which thymocytes and macrophages originated, because of the apparent exception in the mode of phagocytosis by guinea pig macrophages. Evidence demonstrating that antibodies are not involved in this phenomenon will be presented in the accompanying paper.

Recognition of heterologous cells by macrophages. II. The mechanism of phagocytosis of chicken thymocytes by mouse and guinea pig macrophages

Mouse and guinea pig macrophages cultured in vitro actively phagocytize non-opsonized thymocytes from certain heterologous animals including chickens, as shown in the accompanying paper (11). The present study was undertaken to investigate the mechanism of this phenomenon, using the phagocytosis of chicken thymocytes (c-thymocytes) by mouse and guinea pig macrophages. The involvement in this phenomenon of natural IgG passively adsorbed in situ to macrophages was excluded, since the phagocytosis of c-thymocytes was not significantly affected by the treatment of macrophages with homologous IgG or rabbit anti-sera directed toward homologous IgG. The involvement of lectin- or sugar-like receptors seems also to be unlikely, since various glycoproteins showed no significant effect. c-Thymocytes treated with normal mouse serum (NMS) but not with heat-inactivated NMS were strongly stained with goat anti-mouse C3 by an indirect immunofluorescent technique, and became extremely vulnerable to adherence to and phagocytosis by mouse macrophages, suggesting that c-thymocytes are an activator of the alternative pathway of mouse complement. These results as a whole raise the possibility that mouse and guinea pig macrophages can phagocytize c-thymocytes by recognizing their activating surfaces of the alternative complement pathway without the participation of exogenously added IgG or complement, as proposed by others in the phagocytosis of rabbit and mouse red blood cells by human monocytes.

Chronologic changes of activities of naphthol AS-D acetate esterase and other nonspecific esterases in the mononuclear phagocytes of tuberculous lesions

Nonspecific esterases of mononuclear phagocytes (MNs) were studied histochemically in the developing and healing tuberculous lesions produced in rabbit skin by bacille Calmette Guérin (BCG). Nonspecific esterases were assayed with the following substrates: naphthol AS-D acetate (AS-D), naphthol AS-D chloroacetate (AS-D Chl), naphthol AS acetate (AS) and alpha-naphthyl acetate (alpha-N), beta-Galactosidase, a lysosomal enzyme of MNs, was also assayed as a marker of MN activation. The number of MNs hydrolyzing AS-D Chl, AS, and alpha-N increased for 2 to 4 weeks after infection. These chronologic changes were similar to that of beta-galactosidase. In contrast, MNs hydrolyzing AS-D appeared predominantly in the healing lesions five to six weeks after infection. These MNs had the morphologic features of balloon-like cells. They contained few lysosomes and gathered in clumps far from the caseous center. The activity of the AS-D esterase was almost completely inhibited by various trypsin inhibitors, but not by the serine esterase inhibitor of phenylmethylsulfonyl-fluoride. These results suggest that the AS-D esterase is a trypsin-like esterase which participates in the healing of tuberculous lesions.

Fortimicins C, D and KE, new aminoglycoside antibiotics

From the fermentation broth of Micromonospora olivoasterospora CS-26 that produced fortimicins A and B three new aminoglycoside antibiotics, fortimicins C, D and KE, were isolated. Fortimicins C and D exhibited potent, broad spectrum antibacterial activities against Gram-positive and negative bacteria, while fortimicin KE was only weakly active.

Superoxide production in pulmonary alveolar macrophages and killing of BCG by the superoxide-generating system with or without catalase

The superoxide production of BCG-infected and noninfected alveolar macrophages was measured by superoxide dismutase-inhibitable nitro blue tetrazolium reduction. The cells were incubated with or without cell-free bronchial lavage fluid (pulmonary washings). When control alveolar macrophages were infected by BCG, superoxide production was decreased markedly, probably due to bacterial cytotoxic factors. In contrast, the production of superoxide in alveolar macrophages exposed to pulmonary washings was increased and not appreciably influenced by BCG infection. Superoxide production by alveolar macrophages was dependent on time and on the protein concentration in the pulmonary washings. In controls, it was inversely proportional to the infecting dose of BCG. We observed previously that alveolar macrophages activated by pulmonary washings inhibited intracellular growth of BCG. We now present evidence that enhanced production of superoxide contributes to such inhibition, especially in the presence of catalase at acid pH. These findings are pertinent to the defense of inflamed lungs, where serum and serum immunoglobulin G transuded from blood into alveolar spaces probably induce such activation on alveolar macrophages.