Soluble CTLA-4 in sera of patients with bronchial asthma.

Cytotoxic lymphocyte associated antigen-4 (CTLA-4) is a homologue of CD28, which plays a critical role in the down-regulation of antigen-activated immune response. The aim of the present study was to investigate the concentrations of soluble CTLA-4 in sera of patients with bronchial asthma and the correlation between soluble CTLA-4 concentrations and some clinical measures of asthma. The concentrations of serum soluble CTLA-4 in 31 atopic asthmatics, 20 non-atopic asthmatics, and 28 non-atopic normal control volunteers were determined by ELISA technique, and the relationship between serum soluble CTLA-4 concentrations in asthmatics and airway responsiveness, pulmonary function, blood white cell counts and differentials, respectively, were analyzed. Serum soluble CTLA-4 concentrations in both atopic asthmatics (20.2 +/- 5.4 microg/L) and non-atopic asthmatics (19.2 +/- 6.2 microg/L) were all higher than that in normal controls (1.8 +/- 0.8 microg/L, p = 0.04 and 0.014, respectively). There was no difference in serum soluble CTLA-4 concentrations between atopic and non-atopic asthmatics (p = 0.877). The serum soluble CTLA-4 concentrations in the asthmatics statistically correlated with forced expiratory volume in one second (r = -0.410, p = 0.027), percentage of predicted peak expiratory flow (r = -0.449, p = 0.015), and PaCO2 (r = 0.555, p = 0.002), respectively. Our data also showed that the concentration of soluble CTLA-4 was significantly related to blood lymphocyte numbers. The serum soluble CTLA-4 protein level was significantly elevated in patients with asthma. This level correlated with the severity of asthma. Our data also showed that the concentration of soluble CTLA-4 was significantly related to blood lymphocyte numbers.