Release of Immune Modulation Factors from Platelet Concentrates during Storage after Photochemical Pathogen Inactivation.
Authors: Corash Laurence , Cognasse Fabrice , Osselaer Jean-Claude , Messe Natalie , Garraud Olivier 
Published: April 2020

Abstract
Background. Platelets (plt) prepared for transfusion contain multiple molecules that modulate immune function, mediate acute transfusion reactions, induce immune responses, and affect hemostasis. These cytokines/chemokines are secreted differentially from plt during storage (Transfusion2006;46:1184), and may be affected by processing, including pathogen inactivation.
Aims. The INTERCEPT Blood System (IBS) for platelets utilizes amotosalen-HCl (S-59) with ultraviolet A (UVA) light to inactivate a broad spectrum of pathogens and leukocytes. This study was designed to evaluate the effects of photochemical treatment on in vitro release of immune modulation molecules after processing during 7 days (d) of storage.
Methods. Platelet concentrates (n = 10) collected by aphaeresis (CPA) with process leuko-reduction (&lt; 106) containing 8.15x1011 ± 0.8 platelets were suspended in 35% donor plasma and 65% platelet additive solution (Intersol, Baxter, France) and divided into two equal components. One served as an untreated control (C) and the other was prepared with 150 uM amotosalen and a 3 J/cm2 UVA photochemical treatment (PCT) and stored at 22°C with shaking for 7 days. Platelet concentration (106/uL), pH and levels of immune modulation factors were measured: CD62p(ng/mL), PDGF-AB(ng/mL), IL8(pg/mL), sCD40L(pg/mL), IL1β(pg/mL) and TNFα(pg/mL). The concentration of each factor was determined by specific enzyme linked immunosorbent assays in plt and supernatant (s) fractions isolated from stored PCT and C plt components. Mean values ± SD were calculated and compared by paired t-test.
Results. Platelet content, pH and cytokine/chemokine content and release from CPA prepared with photochemical treatment were not statistically different (p &gt; 0.05) from C during 7 d of storage (Table). From d1 to d7, the pH of PCT and C units decreased similarly, but remained within acceptable ranges. No detectable IL1β and TNFα were observed in PCT or C CPA. During platelet storage CD62p, PDGF-AB, IL8, and sCD40L increased similarly in supernatants of PCT and C units. The increase in supernatant levels correlated with a decrease of these cytokines in plt. Platelets in PCT and C retained measurable levels of CD62, IL8, sCD40L and PDGF-AB though 7 d. Levels of sCD40L demonstrated marked variation.
Conclusions. Cytokines increased moderately in the supernatants of CPA and decreased in platelets during storage. After 7 d C and PCT platelets in CPA retained detectable levels of cytokines. PCT had no differential influence on release of immune modulation molecules in vitro over 7 d of storage.
Day O O 5 5 7 7 Product C PCT C PCT C PCT pH 7.1 ±.1 7.1 ±.1 6.9 ±.1 6.8 ±.1 6.9 ±.1 6.8 ±.1 Plt ct 1.29 ±.3 1.30 ±.2 1.30 ±.3 1.19 ±.2 1.27 ±.2 1.18 ±.2 CD62p-s 89 ± 21 87 ± 17 110 ± 23 115 ± 27 117 ± 22 119 ± 25 CD62p-plt 149 ± 33 151 ± 33 141 ± 23 141 ± 25 139 ± 25 139 ± 26 PDGF-s 14.5 ± 3.5 13.6 ± 3.5 17.7 ± 2.4 15.8 ± 1.5 18.0 ± 2.1 17.5 ± 1.8 PDGF-plt 28.3 ± 3.5 30.3 ± 3.1 25.2 ± 3.6 24.9 ± 2.5 23.2 ± 4.0 23.3 ± 3.3 IL8-s 107 ± 17 108 ± 14 136 ± 42 116 ± 9 123 ± 20 120 ± 22 IL8-plt 135 ± 29 134 ± 28 110 ± 11 117 ± 12 103 ± 17 119 ± 32 CD40L-s 51 ± 86 66 ± 94 172 ± 157 237 ± 214 188 ± 198 201 ± 167 CD40L-plt 990 ± 805 1098 ± 747 485 ± 373 474 ± 331 346 ± 293 314 ± 282