Peripheral blood CD4+T-lymphocyte counts during Pneumocystis carinii pneumonia in immunocompromised patients without HIV infection

Study objectives: To assess the potential use of peripheral blood CD4 + T-l ymphocyte counts (CD4 + counts) as a clinically useful biological marker to identify specific immunocompromised patients (without HIV infection) at hi gh risk for Pneumocystis carinii pneumonia (PCP). Design: Prospective observational study. Setting: Three hundred seventy-five-bed tertiary-care urban referral teachi ng hospital, and 250-bed community-based referral hospital. Patients: One hundred seventy-one consecutive confirmed HIV-seronegative ho spitalized and ambulatory adults, including 22 patients with active PCP, 8 patients with bacterial pneumonia, 24 persons in two groups considered at h igh clinical risk, 38 persons in two groups considered at low or undefined risk, and 79 persons in four groups considered not at risk for PCP (includi ng healthy individuals). Measurements and results: Compared to counts in healthy individuals, median CD4 + counts were significantly decreased in patients with active PCP (61 cells/mu L vs 832 cells/mu L; p = 0.001) where 91% of patients had a CD4 count < 300 cells/mu L at the time of PCP diagnosis. Median CD4 + counts we re also reduced in the high clinical risk groups of recent organ transplant recipients (117 cells/mu L; p = 0.007), 64% with < 300 cells/mu L, and pat ients receiving chemotherapy (221 cells/mu L; p < 0.01), 80% with < 300 cel ls/mu L. For the low or undefined clinical risk groups, the median CD4 + co unts were not significantly reduced, although 39 to 46% of individuals rece iving long-term corticosteroid therapy (alone or in combination with other agents) had CD4 + counts < 300 cells/mu L. Median CD4 + counts in individua ls considered not at risk for PCP were similar to those in healthy subjects . Compared to counts in patients with active PCP, median CD4 + counts were significantly higher in bacterial pneumonia patients (486 cells/mu L; p < 0 .05, but similar to those in healthy subjects. Conclusions: These data suggest that for immunosuppressed persons without H IV infection (especially in low or undefined PCP risk groups), CD 4 + count s may be a useful clinical marker to identify specific individuals at parti cularly high clinical risk for PCP and may help to guide chemoprophylaxis.