T lymphocytes are essential for initiation of fungal keratitis in mice (40.14)

Abstract

Abstract In preliminary study, we found that experimental fungal keratitis (FK) induced an adaptive immune response that involved T lymphocytes infiltration and antibody accumulation in corneas. Here we explored the role of T lymphocytes in the progess of FK. Immunocompetent Balb/c mice and nude mice on Balb/c background were utilized. For adoptive transfer of lymphocytes, B cells and T cells were isolated from Balb/c mice spleens and transferred into nude mice via intravenous injection respectively. Experimental FK was induced by intrastromal injection of Candida albicans or Aspergillus fumigatus spores into the corneas one day after reconstitution. Development of corneal disease was measured by scoring the lesions in the corneas. We found that while immunocompetent Balb/c mice developed typical FK after pathogen challenge, T-lymphocytes deficient nude mice did not show any sign of microbial infection after challenge with same amount of fungal spores. Pre-infection reconstitution of nude mice with 2x10^7 T lymphocytes, and not with same number of B lymphocytes nor with 0.66x10^7 T lymphocytes, recovered the susceptibility of the nude mice to FK, and the disease in T cells-reconstituted nude mice were much more severe than in similarly infected Balb/c mice. We conclude that T lymphocytes above a threshold amount are essential in the initiation of keratitis when corneas are insulted by fungi, and T lymphocytes play a dual role in the pathogenesis and prognosis of fungal keratitis.