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Mycoplasma fermentans (incognitus strain) cells are able to fuse with T lymphocytes
D S Dimitrov1, G Franzoso, M Salman
1Section on Membrane Structure and Function, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
Abstract:
Characteristics of the fusion of Mycoplasma fermentans (incognitus strain) with cultured lymphocytes were investigated. The rate and extent of fusion were monitored continuously in an assay that measured lipid mixing on the basis of dequenching of a fluorescent probe, octadecylrhodamine (R18), incorporated into mycoplasmas. Fusion of M. fermentans was detected with CD4+ (Molt-3) cells, CD4- (12E1) cells, and primary peripheral-blood lymphocytes. The level of fusion was relatively low (8%-12%). Detection of a similarly low level of fusion by fluorescence microscopy suggested the involvement of a specific lymphocyte subpopulation. After a short lag period, fusion at 37 degrees C proceeded exponentially for approximately 30 minutes and was virtually complete at 60 minutes. Throughout the process, lymphocytes remained intact. Fusion was stimulated by CaCl2 but not by MgCl2; its inhibition by antisera to M. fermentans and by pretreatment of M. fermentans with proteolytic enzymes implied that the mycoplasmas possessed a proteinase-sensitive receptor involved in fusion. Mycoplasmas were rendered nonfusogenic by treatment with the uncoupler CCCP (carbonyl cyanide m-chlorophenylhydrazone; 5 microM) but were unaffected by treatment with chlorpromazine (10 microM) or DCCD (dicyclohexylcarbodiimide; 50 microM); these findings suggested that a proton gradient across the cell membrane is required for fusion.
Insights
This study reveals Mycoplasma fermentans fusion with lymphocytes. Fusion requires a proteinase-sensitive receptor and a proton gradient, suggesting specific cellular interactions.
Area of Science:
- Cell Biology
- Microbiology
- Immunology
Background:
- Mycoplasma fermentans, particularly the incognitus strain, can interact with host cells.
- Understanding the mechanisms of mycoplasma-host cell fusion is crucial for cellular and molecular biology.
Purpose of the Study:
- To investigate the characteristics of Mycoplasma fermentans fusion with cultured lymphocytes.
- To identify factors influencing the fusion process and the underlying molecular mechanisms.
Main Methods:
- Continuous monitoring of fusion using lipid mixing assay with octadecylrhodamine (R18) fluorescent probe.
- Fusion detection with CD4+ (Molt-3) cells, CD4- (12E1) cells, and primary peripheral-blood lymphocytes.
- Analysis of fusion kinetics, temperature dependence, and effects of various chemical agents (CaCl2, MgCl2, CCCP, chlorpromazine, DCCD) and biological treatments (antisera, proteolytic enzymes).
Main Results:
- Mycoplasma fermentans exhibited low-level fusion (8%-12%) with lymphocytes, suggesting involvement of specific subpopulations.
- Fusion occurred exponentially at 37°C within 60 minutes, with lymphocytes remaining intact.
- Fusion was stimulated by CaCl2, inhibited by antisera to M. fermentans and proteolytic enzyme pretreatment, indicating a proteinase-sensitive receptor.
- Proton gradient requirement was suggested by CCCP-induced nonfusogenicity, while chlorpromazine and DCCD had no effect.
Conclusions:
- Mycoplasma fermentans fusion with lymphocytes is a complex process mediated by a proteinase-sensitive receptor.
- A proton gradient across the mycoplasma cell membrane is essential for fusion.
- These findings provide insights into the molecular basis of mycoplasma-host cell interactions.