Blood transfusion and immunomodulation: a possible mechanism

Area of Science:

• Immunology
• Transfusion Medicine
• Cellular Biology

Background:

• Immune responses require antigen-presenting cells to provide both specific antigen and accessory signals to T cells.
• Lack of accessory signals in vitro induces T cell anergy (unresponsiveness).
• Stimulator cells in stored blood express MHC class II but may lose accessory signaling capacity.

Purpose of the Study:

• To investigate the impact of refrigerated storage on the accessory signaling function of blood stimulator cells.
• To determine the implications of diminished accessory signaling on alloimmunization and immunosuppression.
• To assess the effect of irradiation on stimulator cell accessory signaling.

Main Methods:

• Monitoring of class II MHC expression on stimulator cells during refrigerated storage.
• Assessing the accessory signal presentation capacity of stored blood.
• Evaluating the effects of UV-B and gamma irradiation on accessory signal expression.

Main Results:

• Stimulator cells retain class II MHC expression during storage, but accessory signal presentation diminishes over time.
• Accessory signal presentation capacity reaches zero by approximately 13 days of storage.
• UV-B and gamma irradiation inhibit the expression of the accessory signal by stimulator cells.

Conclusions:

• Stored blood exceeding 2 weeks may not induce alloimmunization but could potentially cause immunosuppression.
• Irradiation of blood can impair the accessory signaling function of stimulator cells.
• Findings have implications for transfusion practices and understanding immune modulation by stored blood products.