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Modification of macrophage phagocytosis in murine cryptococcosis
Abstract:
Normal C57BL/6J peritoneal cells exhibited a decreased phagocytosis when cultured with a cell wall antigen of Cryptococcus sp. and lymphocytes from mice infected with C. neoformans. Direct cell-to-cell interaction was not required in that supernatant fluids from cultures of lymphocytes from infected animals could be incubated with normal macrophage monolayers to give comparable suppression. The induction of the suppressor factor required specific cryptococcal antigen; however, suppression at the macrophage level was nonspecific in that the phagocytosis of C. neoformans and Saccharomyces cerevisiae were both decreased. Suppression appeared with lymphocyte supernatants taken from mice infected for 14 days and thereafter. The factor was heat stable, trypsin sensitive, and allospecific.
Insights
Lymphocyte-secreted factors from Cryptococcus neoformans-infected mice suppress macrophage phagocytosis. This immune suppression is antigen-specific in induction but nonspecific at the macrophage level.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Cryptococcus neoformans is an opportunistic fungal pathogen causing cryptococcosis.
- Macrophage phagocytosis is crucial for controlling fungal infections.
- Immune responses to C. neoformans can involve complex regulatory mechanisms.
Purpose of the Study:
- To investigate the effect of lymphocytes from C. neoformans-infected mice on normal macrophage phagocytosis.
- To characterize the nature of the suppressive factor involved.
Main Methods:
- Peritoneal cells from normal C57BL/6J mice were cultured with Cryptococcus sp. antigen and lymphocytes from infected mice.
- Supernatant fluids from lymphocyte cultures were incubated with normal macrophage monolayers.
- Phagocytosis of C. neoformans and Saccharomyces cerevisiae by macrophages was assessed.
- The suppressor factor's heat stability, trypsin sensitivity, and allospecificity were evaluated.
Main Results:
- Normal macrophage phagocytosis was decreased when cultured with infected lymphocytes or their supernatant.
- Direct cell-to-cell contact was not necessary for suppression.
- Suppression required specific cryptococcal antigen for induction.
- Macrophage-level suppression was nonspecific, affecting both C. neoformans and S. cerevisiae phagocytosis.
- The suppressive factor was present in supernatants from 14-day infected mice onwards.
- The factor was heat stable, trypsin sensitive, and allospecific.
Conclusions:
- Lymphocytes from C. neoformans-infected mice produce a suppressive factor affecting macrophage function.
- This factor plays a role in modulating the immune response during cryptococcosis.
- Understanding this suppression mechanism could inform therapeutic strategies for cryptococcosis.