Measurement of cellular immunity in human coccidioidomycosis has important diagnostic and prognostic implications. The coccidioidin skin test has been the standard for the measurement of this, but it is not available in the United States. We examined the utility of measuring surface expression of CD69 on T lymphocytes in whole blood incubated with the coccidioidal antigen preparation T27K as an alternative to the skin test. Seventy donors with active coccidioidomycosis were studied. The mean fluorescent intensity (MFI) of CD69 expression on CD3 lymphocytes in response to T27K was 28.61 ؎ 1.77, significantly greater than the control response of 11.45 ؎ 0.78 (P < 0.001). The MFI CD69 response to T27K above that for the control (MFI CD69 above control) was 6.35 ؎ 2.18 for seven subjects with disseminated coccidioidomycosis who were studied within 5 months of diagnosis. This was significantly below the value of 20.17 ؎ 3.17 for 18 subjects with pulmonary coccidioidomycosis studied within 5 months of diagnosis and the value of 19.58 ؎ 2.91 for 27 subjects with disseminated coccidioidomycosis studied after 5 months of diagnosis (for both, P < 0.05). There was an inverse correlation between coccidioidal clinical score and MFI CD69 above control for all 34 subjects with disseminated coccidioidomycosis (r ‫؍‬ 0.362; P ‫؍‬ 0.036) but not for the 36 subjects with pulmonary disease (r < 0.001; P ‫؍‬ 0.993). Among 30 subjects for whom data were available, there was a highly significant association between the MFI CD69 above control and the supernatant concentrations of gamma interferon, interleukin-2 (IL-2), and tumor necrosis factor alpha (for all, P < 0.001), but not for IL-4, IL-5, or IL-10. These data indicate that in vitro assessment of CD69 expression on T lymphocytes by using T27K may be a useful measure of cellular immune response among subjects with active coccidioidomycosis.

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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 studied in humans. The median percent of CD3+ lymphocytes (CD3+) producing intracellular interferon-gamma (IFN-gamma) 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 < or =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 microl(-1) had> 0.06% of CD3+ produce intracellular IFN-gamma, compared to none of six whose peripheral blood CD4+ lymphocyte concentration was < or =200 cells microl(-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.