Cytokines in Platelet Components Associated with Acute Transfusion Reactions: The Role of sCD40L.

Background. Acute transfusion reactions (ATR) have been attributed to antibodies directed against HLA antigens in platelet components (PLT). Cytokines and chemokines, released from PLT during storage are postulated to mediate ATR, clinical refractoriness, and graft vs. host disease. Reduced plasma levels and leuko-depletion of PLT lower the frequency of some, but not all, ATR and allo-immunization. Among platelet factors, soluble CD40L (sCD40L) plays a key role in immunology. CD40/CD40L are strongly expressed by activated platelets and CD40L is cleaved to sCD40L. More than 95% of sCD40L in blood is derived from platelets. CD40 is a major regulator of cellular immune interactions and CD40L stimulates monocytes and T cells, suggesting a pleiotropic role for CD40L. Prior studies suggest sCD40L with other mediators are responsible for ATR, especially fever. Aims. As part of a safety study to monitor ATR for PLT prepared with pathogen inactivation, we identified transfusions associated with ATR. Implicated PLT were sampled to characterize cytokine/chemokine profiles in comparison to PLT not associated with ATR(control). Methods. PLT were collected by apheresis at the Mont Godinne Blood Transfusion Center (BTCMG) with process leuko-reduction, suspended in 35% donor plasma and 65% additive solution (Intersol, Baxter, France) and treated with 150uM amotosalen and 3 J/cm² UVA for pathogen inactivation (INTERCEPT, Cerus, Concord, CA). Treated PLT were stored up to 7 days until issued for transfusion. Transfusion of PLT required completion of a case report form to monitor the response to transfusion. PLT implicated in ATR were sampled to determine cytokine profiles. Frozen samples (−20 °C) of PLT were sent to EFS Auvergne Loire to assay CD62p(ng/mL), PDGF-AB(ng/mL), IL8(pg/mL), and sCD40L(pg/mL) by specific enzyme linked immunosorbent assays in platelets (plt) and supernatant (s) fractions isolated from the implicated PLT. Cytokine levels in PLT without ATR (Control) were measured in 10 PLT after 5 and 7 days of storage (5d CTL; 7d CTL). Results. In the 18-months after adoption of INTERCEPT PLT compared to the 18-months prior, ATR decreased from 1.3% to 0.9% of transfusions (n = 7,580: