-Reactive T Cells for the Diagnosis of Invasive Infection-A Prospective Pilot Study

Blood or tissue culture or histology prove invasive infection, but long time to result, limited feasibility and sensitivity call for new approaches. In this pilot project, we describe the diagnostic potential of quantitating -reactive, CD4/CD69/CD154 positive lymphocytes in blood of patients with invasive infection. We used flow cytometry quantitating -reactive, CD4/CD69/CD154 positive lymphocytes from peripheral blood of patients with invasive infection, from patients at risk and healthy volunteers as controls. Elevated levels of -reactive lymphocytes were measured in 13 patients with proven invasive infection and in one patient with probable hepatosplenic candidiasis. Results of three candidemia patients were uninterpretable due to autofluorescence of samples. Twelve of 13 patients had identified to species level by conventional methods, and T cell reactivity correctly identified species in 10 of 12 patients. Nine hematological high-risk patients and 14 healthy donors had no elevated -reactive T cell counts. This -reactive lymphocyte assay correctly identified the majority of patients with invasive infection and the respective species. Our assay has the potential to support diagnosis of invasive infection to species level and to facilitate tailored treatment even when biopsies are contraindicated or cultures remain negative.