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Cultures of Chlamydia trachomatis in mouse peritoneal macrophages: factors affecting organism growth
Abstract:
Growth of Chlamydia trachomatis B/TW-5/OT and L(2)/434/Bu strains in cultures of thioglycolate-activated mouse peritoneal macrophages was studied. Both strains grew to a limited extent in the macrophages, but lymphogranuloma venereum (LGV) grew better than trachoma. Growth was enhanced by centrifugation of the inoculum onto the macrophage cell layer and inhibited by pretreatment of macrophages for 2 h with 100 mug of concanavalin A per ml. No significant effect was observed by pretreatment of macrophages with diethylaminoethyl-dextran (30 mug/ml, 30 min), cytochalasin B (20 mug/ml, 1 h), and cyclophosphamide (200 mug/ml, overnight) or by treatment with hydrocortisone (1 and 10 mug/ml, overnight before inoculation and during a 2-day incubation after inoculation). Resistance to intracellular growth of the two organisms was not increased in macrophages obtained from mice immunized with the organisms compared with macrophages from nonimmunized mice unless they were pretreated in vitro with penicillin (100 U/ml, overnight). The yields of LGV organisms from the penicillin-pretreated macrophages of LGV-immunized mice were 100-fold less than from the pretreated macrophages of nonimmunized control mice. At the same time, the yields of LGV organisms from penicillin-pretreated macrophages of mice immunized with trachoma, gonococcus, and HeLa cells were not different from those obtained in pretreated macrophages of nonimmunized control mice.
Insights
This study investigated Chlamydia trachomatis growth in mouse macrophages, finding lymphogranuloma venereum (LGV) grew better than trachoma. Penicillin pretreatment of macrophages from immunized mice significantly reduced LGV yields.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Chlamydia trachomatis causes trachoma and lymphogranuloma venereum (LGV).
- Understanding Chlamydia's intracellular growth mechanisms is crucial for developing effective treatments.
- Macrophages play a key role in the host immune response to Chlamydia infections.
Purpose of the Study:
- To investigate the intracellular growth of Chlamydia trachomatis B/TW-5/OT (trachoma) and L(2)/434/Bu (LGV) strains in mouse peritoneal macrophages.
- To evaluate the effect of various pre-treatments on Chlamydia growth within macrophages.
- To assess the role of macrophage immunization and penicillin treatment in controlling Chlamydia infection.
Main Methods:
- Culturing thioglycolate-activated mouse peritoneal macrophages.
- Inoculating macrophages with Chlamydia trachomatis strains.
- Pre-treating macrophages with concanavalin A, diethylaminoethyl-dextran, cytochalasin B, cyclophosphamide, and hydrocortisone.
- Immunizing mice and obtaining macrophages for infection studies.
- Treating infected macrophages with penicillin.
Main Results:
- Both Chlamydia strains grew to a limited extent in macrophages, with LGV showing enhanced growth compared to trachoma.
- Macrophage growth was enhanced by inoculum centrifugation and inhibited by concanavalin A pre-treatment.
- Penicillin pre-treatment of macrophages from LGV-immunized mice significantly reduced LGV yields (100-fold) compared to non-immunized controls.
Conclusions:
- Macrophage immunization alone did not confer resistance to Chlamydia intracellular growth.
- Penicillin pre-treatment, particularly in conjunction with LGV-specific immunization, significantly enhances macrophage control over LGV replication.
- These findings highlight the potential of combining immunomodulation with antimicrobial therapy for Chlamydia infections.