Plasma levels of sCD40L in SLE patients were higher than in HD (50.58 ± 25.79 pg/ml for HD vs. 691.3 ± 268.7 pg/ml for SLE, p < 0.01) and correlated with the percentage of each subpopulation of lymphocytes with bound platelets in SLE patients (Figures 2(d)–2(f)), though not in HD (r = 0.18, p = 0.66 for CD19+PLT+; r = 0.5, p = 0.25 for CD4+PLT+; and r = 0.28, p = 0.49 for CD8+PLT+). Here, CD4 is linked to systemic lupus erythematosus.