Related Experiment Videos
Evidence for macrophage-mediated protection against lethal Candida albicans infection
Abstract:
Systemic infection of mice with a Candida albicans strain (PCA-2) incapable of yeast-mycelial conversion conferred protection against a subsequent intravenous challenge with the pathogenic strain of the parent organism, strain CA-6. Protection was nonspecific since it was also detected upon challenge of mice with Staphylococcus aureus. Moreover, the PCA-2 organisms had to be viable, their effects being most evident when they were given intravenously at a dose of 10(6) cells 7 to 14 days prior to microbial challenge. Thus, all mice pretreated with PCA-2 and challenged 14 days later with viable CA-6 cells lived through a 60-day observation period, whereas all control mice not treated with PCA-2 died within 3 days. In an attempt to correlate the immunostimulatory effects observed in vivo with possible modifications in in vitro functions, it was found that administration of PCA-2 was accompanied by an increase in the number of peripheral blood polymorphonuclear cells and by the activation in the spleen of cells with highly candidacidal activity in vitro. Moreover, the adoptive transfer of plastic-adherent cells from PCA-2-infected mice into histocompatible recipients conferred considerable protection against subsequent CA-6 challenge.
Insights
A non-pathogenic Candida albicans strain (PCA-2) boosts the immune system, protecting mice against subsequent infections. This immune stimulation, mediated by specific immune cells, offers broad protection against microbial challenges.
Area of Science:
- Immunology
- Microbiology
- Infectious Diseases
Background:
- * Candida albicans is a common fungal pathogen.
- * Understanding host immune responses is crucial for developing effective treatments.
- * Non-pathogenic strains can sometimes elicit protective immunity.
Purpose of the Study:
- * To investigate the protective effects of a non-mycelial Candida albicans strain (PCA-2) against subsequent infections.
- * To determine the mechanisms underlying this protection.
- * To assess the specificity and optimal conditions for this protective effect.
Main Methods:
- * Systemic infection of mice with viable PCA-2 strain.
- * Subsequent intravenous challenge with pathogenic Candida albicans (CA-6) or Staphylococcus aureus.
- * Monitoring survival rates and immune cell activity (polymorphonuclear cells, spleen cell candidacidal activity).
- * Adoptive transfer of plastic-adherent cells.
Main Results:
- * Pretreatment with viable PCA-2 significantly protected mice against lethal CA-6 challenge, with all treated mice surviving 60 days versus 3 days for controls.
- * Protection was non-specific, also effective against Staphylococcus aureus challenge.
- * Optimal protection observed when PCA-2 was administered intravenously 7-14 days prior to challenge.
- * PCA-2 administration increased peripheral blood polymorphonuclear cells and activated spleen cells with candidacidal activity.
- * Adoptive transfer of plastic-adherent cells from PCA-2-treated mice conferred protection.
Conclusions:
- * Viable, non-mycelial Candida albicans strain PCA-2 confers significant, non-specific protection against microbial infections in mice.
- * This protection is mediated by enhanced innate immune cell activity, including polymorphonuclear cells and activated spleen cells.
- * The findings suggest potential for using attenuated fungal strains as immunomodulatory agents for infection prophylaxis.