Plasma sCD40L and platelet-associated CD40L.
(A) Levels of sCD40L were measured by ELISA in the plasma of 200 Caucasian patients divided in 5 groups: group 1 includes patients with low platelet numbers; group 2, controls with a normal platelet count; group 3, patients with inflammatory disorders but with a normal platelet count; group 4, patients with RT; and group 5, those with ET. The medium bar within the box represents the median value. The outlines of the boxes show the 25% and the 75% percentiles, while the bars outside the boxes represent the 10% and 90% percentiles. (o) indicates values outside this range. Comparisons between groups are statistically significant (nonparametric Mann-Whitney Utest) (P = .03 between groups 1 and 2;P = .009 between groups 4 and 5;P = 10−6 for other comparisons between each group). (B) Correlation between the platelet counts and the plasma concentrations of sCD40L (Spearman test, R = 0.818,P = .001). (C) Concentrations of sCD40L (ng/mL) in the supernatant of 250 × 109/L (250 000/μL) platelets unstimulated (□) or stimulated with thrombin (▵) or in platelet lysates (◊) from controls (n = 8), patients with RT (n = 9), or patients with ET (n = 13). There is no difference between groups in the supernatant of unstimulated platelets. In contrast, comparisons between groups are statistically significant (nonparametric Mann-Whitney U test) in the supernatant of activated platelets (P = .01 between controls and RT,P = 10−4 between controls and ET, andP = .048 between RT and ET) and in platelet lysates (P = .01 between controls and RT,P = 10−4 between controls and ET, andP = .002 between RT and ET). Results were confirmed on 4 patients of each group with an independent ELISA measurement (ELISA kit from R&D kit).
