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Bidirectional amplification of macrophage-lymphocyte interactions: enhanced lymphocyte activation factor production
Abstract:
Adherent peritoneal cells (90 to 95% macrophages) from mice injected with Mycobacterium bovis, strain BCG, or certain noninfectious agents such as pyran copolymer or phytohemagglutinin showed increased chemotactic and tumoricidal capacity in vitro. These activated macrophages elaborated 2 to 5 times more lymphocyte-activating factor (LAF) in vitro than equal numbers of adherent cells from untreated mice. In contrast, adherent PC from mice treated with thioglycollate or mineral oil were not cytotoxic and did not produce more LAF than PC from untreated mice. Adherent PC from untreated nude mice, which have increased chemotactic and tumoricidal capacity in vitro, also exhibited enhanced LAF production compared to adherent PC from their normal littermates. Increased production of LAF was also evident with adherent PC and the macrophage-like tumor cell line P388D1 after incubation in vitro with bacterial endotoxins or with antigen-induced lymphokines. These data indicate that adherent PC can be activated either in vivo or in vitro to elaborate more LAF. Thus, activated macrophages are more effective than normal macrophages in amplification of the afferent limb of immune responses as well as in their effector functions.
Insights
Activated macrophages, key immune cells, show enhanced tumor-killing and immune response amplification abilities. This study reveals how activating macrophages boosts their effectiveness in fighting infections and cancer.
Area of Science:
- Immunology
- Cell Biology
- Cancer Research
Background:
- Macrophages are crucial immune cells involved in host defense.
- Macrophage activation influences their functional capabilities.
- Understanding macrophage activation is key to developing immunotherapies.
Purpose of the Study:
- To investigate the functional changes in macrophages upon activation.
- To determine the impact of activation on lymphocyte-activating factor (LAF) production.
- To explore the role of activated macrophages in immune response amplification.
Main Methods:
- Adherent peritoneal cells (macrophages) were isolated from mice treated with BCG, pyran copolymer, or phytohemagglutinin.
- Chemotactic and tumoricidal capacities were assessed in vitro.
- Lymphocyte-activating factor (LAF) production was measured.
- Macrophage activation was also induced in vitro using bacterial endotoxins and lymphokines.
Main Results:
- Activated macrophages exhibited enhanced chemotactic and tumoricidal capacity in vitro.
- Activated macrophages produced 2-5 times more LAF compared to untreated controls.
- Macrophages from untreated nude mice also showed increased LAF production.
- In vitro activation with endotoxins or lymphokines increased LAF production.
Conclusions:
- Macrophage activation, both in vivo and in vitro, significantly enhances LAF production.
- Activated macrophages demonstrate superior effector functions, including tumoricidal activity.
- Enhanced LAF production by activated macrophages amplifies immune responses, contributing to host defense.