The influence of murine alpha/beta-interferon (Mu IFN-alpha/beta) and murine gamma-interferon (Mu IFN-gamma) preparations on the attachment and ingestion phase of phagocytosis by mouse peritoneal macrophages (MPM) was studied. A non-opsonized strain of Escherichia coli, IgG-opsonized E. coli, and sheep erythrocytes opsonized with IgG (E-IgG) and IgM plus complement factor C3b (E-IgMC) were used as test particles. Pretreatment of MPM with 10(2)-10(3) U/ml of Mu IFN-alpha/beta for 24 h enhanced both attachment and ingestion of bacteria or erythrocytes mediated by the non-specific receptor, the Fc receptor, or the C3b receptor. Higher concentrations had no such effects. In contrast, treatment of MPM with 10(1)-10(2)U/ml of Mu IFN-gamma suppressed attachment and ingestion of non-opsonized and IgG-opsonized E. coli and of E-IgG by 10-40%. Mu IFN-gamma did not influence attachment and ingestion of E-IgMC. The effects were neutralized by specific anti-IFN antiserum. The data indicate that the IFN effect on phagocytic activity is, at least to a large extent, due to modifications of the surface receptors.

No abstract

We have studied the effect of recombinant murine interferon-gamma (rMuIFN-gamma) on the protein content, phagocytic activity, and cytotoxicity of mouse peritoneal macrophages (MPM). The aim of this study was to see whether rMuIFN-gamma alone could influence these parameters of MPM activity or if an additional stimulus, like elicitation or cultivation with lipopolysaccharide (LPS), was required. The MPM cultures were treated with rMuIFN-gamma for 24, 48, or 72 h. Generally, rMuIFN-gamma treatment of the cultures increased the protein content of the MPM. MPM were generally cytotoxic and they phagocytized IgG-opsonized Escherichia coli under the experimental conditions of this study. The effects of rMuIFN-gamma on phagocytic and cytotoxic activities were complex and highly dependent on the dose and length of treatment. Low or high concentrations may exert opposite effects on the same functions. Addition of a low dose of LPS to the cultures did not generally amplify the rMuIFN-gamma-induced alterations of MPM activities. However, the combination of LPS, high doses of rMuIFN-gamma, and long incubation time reduced the protein content, suppressed the phagocytic activity, and negatively influenced the viability of the MPM. Thioglycolate-elicited MPM had a higher baseline activity than resident MPM, but the rMuIFN-gamma effect on elicited MPM was parallel to the effect on resident MPM.

The effect of acyclovir (ACV) treatment on selected functions of human blood-derived macrophages was examined. ACV was not cytotoxic when applied in a wide range of concentrations. Only minor effects on macrophage functions were observed when cells were treated with therapeutic concentrations of ACV: phagocytosis and the production of interferon and tumor necrosis factor were slightly enhanced, while the production of lysozyme was reduced, in a dose-dependent manner. Interferon production was also reduced in the presence of high concentrations of ACV.

Several macrophage functions are modulated by treatment with homologous interferon (IFN). For example, phagocytic activity of mouse peritoneal macrophages (MPM) is enhanced by moderate concentrations of mouse fibroblast interferon (MuIFN-P) (Rollag & Degré 1981). Spreading of freshly seeded macrophages on glass surfaces is stimulated by macrophage-activating agents (Mörland & Kaplan 1977), IFN inducers (Rabinovitch et al . 1977) and IFN (Schultz et al . 1978). We report here quantitative data on effect of MuIFN-β on the spreading of MPM in vitro . Cells were seeded on glass surfaces in Eagle’s MEM, and spreading was examined after incubation at 37 °C for various periods by phase-contrast light microscopy (p.c.m.). Cells, fixed in 2.5% glutaraldehyde, were scored as round or spread, at least 200 cells in each preparation (Rabinovitch & De Stefano 1973).