. 2020 May 17;43(1):58–64. doi: 10.1016/j.htct.2020.03.003

Table 2.

Proposed mechanisms of transfusion-related immunomodulation (TRIM).

• Intact allogeneic mononuclear cells present in cellular blood products

• Persistence of small numbers of allogeneic WBCs in the transfusion recipient circulation (microchimerism)

• Type Th2 immunosuppressive cytokines secreted by blood cells during storage of RBCs or platelets

• Type Th1 pro-inflammatory cytokines released during storage of blood components (“inflammatory” TRIM)

• Induction of CD4⁺ Treg cells activation suppressing the Th1 response

• Soluble molecules including HLA Class I peptides circulating in allogeneic plasmatic components

• Biologic mediators (bioactive non-polar lipids, eicosanoids, iron, etc.…) released into the supernatant of RBC units during storage (storage lesion)