CD8A and lymphopenia: Flow cytometry of the patient’s peripheral blood lymphocytes revealed undetectable levels of peripheral B cells (0.0%; reference, 5–18%), CD4-positive T-cell lymphopenia (22.5%; reference, 27–51%), a CD4-positive T-cell count of 754/μL, a CD8-positive T-cell count of 2134/μL, and an inverted CD4-positive/CD8-positive cell ratio (0.4; reference, 0.7–2.8).