Changes in serum neopterin and serum beta 2-microglobulin in subjects with lung infections.

Our aim was to investigate whether serum neopterin and beta 2-microglobulin have any value in the distinction between Pneumocystis carinii pneumonia (PCP) and pneumonia due to extracellular bacteria. Also, to study whether neopterin and beta 2-microglobulin would correlate with the clinical course of lung infections in human immunodeficiency virus (HIV)-positive and HIV-negative patients. Thirty HIV-positive subjects with PCP, 9 HIV-positive patients with bacterial pneumonia, and 16 HIV-negative patients with bacterial pneumonia were investigated. Thirty eight asymptomatic HIV-positive subjects and 48 healthy blood donors were used as controls. The HIV-positive patients with PCP and the HIV-positive subjects with bacterial pneumonia had significantly and similarly elevated levels of neopterin and beta 2-microglobulin in the acute stage. In the weeks before the acute stage of PCP, neopterin and beta 2-microglobulin had been increasing. After start of treatment, serum neopterin declined significantly, whilst serum beta 2-microglobulin remained elevated. The HIV-negative patients with bacterial pneumonia had significantly increased serum concentrations of both markers in the acute stage, and had decreasing serum concentrations in the weeks after treatment. We conclude that neither neopterin nor beta 2-microglobulin seem to be of value in distinction between PCP and bacterial pneumonia in HIV-positive subjects. In the HIV-positive patients, neopterin may correlate partly with the clinical activity of PCP, whilst serum beta 2-microglobulin may remain elevated after PCP, despite treatment and recovery. The elevated level may, in part, be due to repeated infections and progression to acquired immune deficiency syndrome (AIDS).(ABSTRACT TRUNCATED AT 250 WORDS)