Elevated serum concentrations of soluble CD14 in HIV- and HIV+ patients with tuberculosis in Africa: prolonged elevation during anti-tuberculosis treatment

Data are limited regarding serum concentrations of soluble CD14 (sCD14), a marker of macrophage activation, in patients with active tuberculosis (TB) and during drug treatment. In this study, concentrations of sCD 14 were mea sured in serum samples obtained from 105 African subjects who were categori zed into one of four groups: persons with pulmonary TB alone (TB+HIV-, n = 30), pulmonary TB and HIV co-infection (TB+HIV+, n = 20), or HIV infection alone (TB-HIV+, n = 25), and healthy controls (TB-HIV-, n = 30). Mean total sCD14 was significantly increased in serum of patients with newly diagnose d pulmonary TB (mean = 6.6 g/ml, s.d. = 1.6 g/ml) compared with healthy con trols (mean = 3.1 g/ml, s.d. = 0.6 g/ml; P < 0.0001), and this elevation co mprised proportionate increases in the alpha (2.1-fold greater, P < 0.0001) and beta (2.0-fold greater, P < 0.0001) forms of sCD14. Total sCD14 was al so increased in serum of HIV-infected patients (mean = 4.1 g/ml, s.d. = 1.9 g/ml; P < 0.01), but the highest concentrations were observed in patients with pulmonary TB and HIV coinfection (mean = 8.7 g/ml, s.d. = 3.1 g/ml; P < 0.0001). Analysis of serum samples prospectively collected from TB+HIV- p atients during the first 3 months of successful anti-TB treatment demonstra ted steep reductions in mean concentrations of the acute-phase protein, C-r eactive protein, and the soluble lymphocyte activation marker, sCD25. In co ntrast, levels of sCD14 increased during the first month of treatment and s lowly declined thereafter. These data indicate that the serum concentration of sCD14 is not a sensitive index of response to anti-TB treatment and sug gest that cellular activation resolves more slowly in the macrophage pool c ompared with the lymphocyte pool during anti-TB treatment.