Dendritic cells are the major antigen presenting cells in inflammatory lesions of murine mycoplasma respiratory disease and contribute to disease severity (P3306)

Abstract

Abstract Mycoplasmas cause chronic respiratory diseases in animals and humans, and vaccine development has been problematic. T cell responses were shown to confer protection as well as promote immunopathology in murine mycoplasma pneumonia. Because T cells play a critical role, the role of antigen presenting cells (APC) was examined as they likely influence either an increase in disease severity or promote protective immunity. The roles of APC, such as dendritic cells (DC) and macrophages, in mycoplasma disease are currently unknown. In this study, we examined the ability pulmonary APC populations and their contribution to T cell responses during disease pathogenesis. Both macrophages and DC increased in the lungs of mice after infection. These cell populations showed different patterns of cytokine mRNA expression, supporting the idea that these cells have different impacts on immunity in response to infection. In fact, DC from the lungs of infected mice were most capable of stimulating mycoplasma-specific T helper (Th) cell responses in vitro. In vivo, DC cells were co-localized with Th cells in inflammatory lesions in the lungs of mycoplasma-infected mice. Intratracheal inoculation of mycoplasma antigen-pulsed DC resulted in increased disease severity after subsequent infection. Thus, DC appear to be the major APC population responsible for pulmonary T cell stimulation in mycoplasma-infected mice, and these DC likely contribute to responses impacting disease pathogenesis.