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 1α, interferon γ (IFN-γ), and tumor necrosis factor α (TNF-α). 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-γ or TNF-α 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/μL; 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-γ/TNF-α-predominant responses were associated with survival. © 2013 The Author. Published by Oxford University Press on behalf of the Infectious Diseases Society of America.