| Objective: To investigate the expressions of platelet-derived CD40, CD40 ligand(CD40L) and serum concentrations of sCD40, sCD40L in asthma patients, and to evaluate the clinical significance of CD40/CD40L in pathogenesis of asthma.Methods: Platelets, plasma and serums were isolated from 57 patients with acute asthma(acute asthma group), 43 stable patients(stable group) and 15 normal subjects(control group). The expression rates of platelet-derived CD40, CD40L, CD62P were measured by flow cytometry before and after adenosine diphosphate(ADP) inducing in vitro. Meanwhile platelets were isolated from 6 participants of three groups respectively, the platelets were stimulated with ADP in vitro for the indicated times, and the levels of CD40, CD40L, CD62P expression were assessed by flow cytometry. The plasma thromboxane B2(TXB2) and 6-keto-PGF1α(6-K-PGF1α) were determined by radioimmunoassay. The serum concentrations of soluble CD40(sCD40) and soluble CD40 ligand(sCD40L) were measured by enzyme linked immunosorbent assay. The pulmonary functions of all participants were evaluated at the same time.Results: (1) The levels of platelet-derived CD40L, CD62P, plasma concentrations of TXB2 and 6-K-PGF1α, TXB2/6-K-PGF1α were all increased in acute asthma group as compared with control group(P<0.05), but there were no differences between the stable group and control group(P>0.05). (2) The expression of CD40L was positively correlated with the expression of CD62P(P<0.01) and this indicated that CD40L could be one of biomarkers of platelet activation. (3) The expressions of platelet-derived CD40L, CD62P gradually declined induced by ADP for the indicated times in acute asthma group. While the expressions of platelet-derived CD40L, CD62P reached their maximum levels after ADP induced for 20 mins and then gradually declined in stable and control groups. Nosame change of platelet-derived CD40 was observed in 3 groups. (4) The serum concentrations of sCD40, sCD40L were increased in acute asthma group compared with that of control and stable groups(P<0.05). The concentrations of sCD40L were higher in patients with severe asthma than those of moderate group(P<0.01) or mild group(P<0.01), but the concentrations of sCD40 had no differences among different severities of asthma patients. (5) The levels of platelet-derived CD40L, CD62P, serum concentrations of sCD40, sCD40L were negatively correlated with their pulmonary functions(P<0.05). (6) CD40 constitutively expressed on the surface of platelets and there were no differences among the three groups(P>0.05).Conclusions: These results suggested that there were high levels expression of platelet-derived CD40L, CD62P and serum concentrations of sCD40, sCD40L in patients with acute asthma, the system of platelet-derived CD40/CD40L might have a potent effect in pathogenesis of asthma. The expression of CD40L had a positive correlationship with the expression of CD62P indicated that CD40L could be one of biomarkers of platelet activation. Inhibition of platelet activation could be another therapy of asthma control, and CD40/CD40L might be an important target molecule on platelets.
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