Assessment of the human cellular immune response to T27K, a coccidioidal antigen preparation, by flow cytometry of whole blood

Whole blood flow cytometry was performed among donors with various clinical forms of coccidioidomycosis using T27K, a coccidioidal antigen preparation protective in mice but not previously studies in humans. The median percent of CD3+ lymphocytes (CD3+) producing intracellular interferon-gamma (IFN-γ) among healthy immune donors was 0.43%, significantly above that for non-immune donors (0.01%) and greater than that for subjects with other forms of coccidioidomycosis, including chronic pulmonary (0.11%), disseminated (0.09%) and concomitant human immunodeficiency virus (HIV) infection (0.07%) (P ≤0.002 for all). No increase in intracellular interleukin (IL)-10 production or apoptosis was noted in samples incubated with T27K. Among 14 HIV-infected patients with concomitant coccidioidomycosis, seven of eight patients whose peripheral blood CD4 concentration was >200 cells μl^-1 had >0.06% of CD3+ produce intracellular IFN-γ, compared to none of six whose peripheral blood CD4+ lymphocyte concentration was ≤200 cells μl^-1 (P = 0.005). These data indicate that there is a specific human cellular immune response to T27K as a coccidioidal antigen and that this response can be categorized based on the clinical status of the coccidioidally infected patient.