To address two questions by means of an animal model: Firstly, does a dose/effect relationship exist between C. albicans load and the emergence of an oral C. albicans infection; secondly, which cellular immune response takes place following inoculation with defined pathogen loads.
Material and Methods:
Immunocompetent inbred mice (Balb/c) (n=19) and mice with combined B- and T-cell defects (SCID) (n=21) were orally inoculated with pathogen loads between 104 and 108C. albicans cells/10 l (strain ATCC 32032). One half of the tongue tissue was examined with the Periodic Acid Schiff (PAS) method for displaying the invasion of hyphae. The other half of the tissue was examined by immune peroxidase technique for analyzing the distribution of immunocompetent cells (CD4, CD54, CD74, CD103) in the epithelial layers and subepithelial connective tissue.
One week following the inoculation, neither groups tissue showed clinical signs of oral candidiasis. Using PAS preparation hyphae were seen with the inoculation dose of 108C. albicans cells in the case of Balb/c mice and a load of 105 pathogens in SCID mice. The extent of the immunologic reaction depended both on the inoculation dose given to the animals and on their immune status.
Despite the lack of clinical signs of oral candidiasis in both groups tissue, infections of the tongue epithelium were evident histologically leading to immunologic reactions of the tongue mucosa.
Candida, candidiasis, immunologic dose response relationship, oral