Sensitized CD8+ T cells fail to control organism burden but accelerate the onset of lung injury during Pneumocystis carinii pneumonia.
While CD8+ cells have been shown to contribute to lung injury during Pneumocystis carinii pneumonia (PCP), there are conflicting reports concerning the ability of CD8+ cells to kill P. carinii. To address these two issues, we studied the effect of the presence of CD8+ cells in two mouse models of PCP. In the reconstituted SCID mouse model, depletion of CD8+ cells in addition to CD4+ cells after reconstitution did not result in increased numbers of P. carinii cysts compared to the numbers of cysts in mice with only CD4+ cells depleted. This result was observed regardless of whether the mice were reconstituted with naïve or P. carinii-sensitized lymphocytes. In contrast, reconstitution with sensitized lymphocytes resulted in more rapid onset of lung injury that was dependent on the presence of CD8+ cells. The course of organism replication over a 6-week period was also examined in the CD4+-T-cell-depleted and CD4+- and CD8+-T-cell-depleted mouse model of PCP. Again, the organism burdens were identical at all times regardless of whether CD8+ cells were present. Thus, in the absence of CD4+ T cells, CD8+ T cells are a key contributor to the inflammatory lung injury associated with PCP. However, we were unable to demonstrate an in vivo effect of these cells on the course of P. carinii infection.
Gigliotti
Francis
F
Department of Pediatrics, University of Rochester School of Medicine & Dentistry, 601 Elmwood Avenue, Box 690, Rochester, NY 14642, USA. francis_gigliotti@urmc.rochester.edu
Crow
Elliott L
EL
Bhagwat
Samir P
SP
Wright
Terry W
TW
D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000473:pathology; D015169:Colony Count, Microbial; D004195:Disease Models, Animal; D018450:Disease Progression; D008212:Lymphocyte Depletion; D051379:Mice; D016513:Mice, SCID; D045363:Pneumocystis carinii / Q000276:immunology*; D011020:Pneumonia, Pneumocystis / Q000276:immunology* / Q000382:microbiology* / Q000473:pathology; D013154:Spleen / Q000166:cytology / Q000276:immunology / Q000637:transplantation