Alveolar and Blood T Lymphocyte Profiles in Pneumocystis jirovecii–Positive Patients: Effects of HIV Status

Background. There are substantial differences in the risk evaluation, clinical presentation, and outcome of Pneumocystis pneumonia between human immunodeficiency virus (HIV)–positive and HIV-negative immuno-compromised patients. To compare the host immune defenses against Pneumocystis jirovecii, the blood and alveolar lymphocyte profile was explored in these 2 populations. Methods. The total, CD31, CD41, and CD81 T-lymphocyte counts were measured in the blood and alveoli of immunocompromised patients with a P. jirovecii DNA detected in their bronchoalveolar lavage samples, according to their HIV status. Results. In blood and alveoli, the CD41 and CD81 T-lymphocyte counts were higher and lower, respectively, in the HIV-negative group. The threshold for initiating prophylaxis in HIV-positive persons, 200 CD41 T cells/lL, was not pertinent for HIV-negative patients. The P. jirovecii burden correlated with the blood CD41 T-cell counts in the HIV-positive but not in the HIV-negative group. Nevertheless, whatever the HIV status, a correlation was observed between alveolar CD41 T cells and the P. jirovecii burden. Conclusions. The T-lymphocyte profile was different between HIV-positive and HIV-negative patients with P. jirovecii, suggesting a distinct pathogenesis. Alveolar CD41 T cells could be critical to explain the development of Pneumocystis pneumonia but may also be important for evaluation of disease risk, mostly among HIV-negativ