['Blood platelets (PLTs) are critical for hemostasis, and they contain biologically active constituents with the potential to modulate inflammatory responses. This study examined the effects of photochemical pathogen inactivation treatment (PCT) on the release of cytokines and/or chemokines from PLT components.', 'Double-dose apheresis PLT components were suspended in plasma-PLT additive solution mixtures and divided into paired therapeutic units. One unit served as an untreated control and the other unit was treated with PCT. PLT concentrations, pH, and levels of cytokines and/or chemokines (CD62p, platelet-derived growth factor-AB, interleukin [IL]-8, soluble CD40 ligand [sCD40L], IL-1beta, and tumor necrosis factor alpha) were measured during 7 days of storage in PLT component supernatants and PLT lysates.', 'PLT content, pH, and cytokine and/or chemokine content and release from PLT component prepared with PCT were not different (p > 0.05) from paired control components during storage. Levels of sCD40L, however, increased significantly during storage while decreasing in parallel within PLT lysates, although no differences were detected between paired PCT and control PLT component.'] Does release of immune modulation factors from platelet concentrate during storage after photochemical pathogen inactivation treatment?