The Phenotype of the Cryptococcus-Specific CD4+ Memory T-Cell Response Is Associated With Disease Severity and Outcome in HIV-Associated Cryptococcal Meningitis

Background. Correlates of immune protection in patients with human immunodeficiency virus (HIV)-associated cryptococcal meningitis are poorly defined. A clearer understanding of these immune responses is essential to inform rational development of immunotherapies. Methods. Cryptococcal-specific peripheral CD4(+) T-cell responses were measured in 44 patients with HIV-associated cryptococcal meningitis at baseline and during follow-up. Responses were assessed following ex vivo cryptococcal mannoprotein stimulation, using 13-color flow-cytometry. The relationships between cryptococcal-specific CD4(+) T-cell responses, clinical parameters at presentation, and outcome were investigated. Results. Cryptococcal-specific CD4(+) T-cell responses were characterized by the production of macrophage inflammatory protein 1 alpha, interferon gamma (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha). Conversely, minimal interleukin 4 and interleukin 17 production was detected. Patients surviving to 2 weeks had significantly different functional CD4(+) T-cell responses as compared to those who died. Patients with a response predominantly consisting of IFN-gamma or TNF-alpha production had a 2-week mortality of 0% (0/20), compared with 25% (6/24) in those without this response (P = .025). Such patients also had lower fungal burdens (10 400 vs 390 000 colony-forming units/mL; P < .001), higher cerebrospinal fluid lymphocyte counts (122 vs 8 cells/mu L; P < .001), and a trend toward faster rates of clearance of infection. Conclusions. The phenotype of the peripheral CD4(+) T-cell response to Cryptococcus was associated with disease severity and outcome in HIV-associated cryptococcal meningitis. IFN-gamma/TNF-alpha-predominant responses were associated with survival.