Platelets do not adsorb HLA class I molecules during storage of pooled platelet concentrates

Area of Science:

• Immunology
• Transfusion Medicine
• Hematology

Background:

• The origin of Human Leukocyte Antigen (HLA) class I molecules on platelets remains unclear.
• Previous studies suggest HLA molecule adsorption onto platelets under specific experimental conditions.

Purpose of the Study:

• To investigate significant elution and adsorption of HLA class I molecules on platelets during routine storage of pooled random platelet concentrates (PRPC).

Main Methods:

• Prepared HLA-A2-positive and negative platelet concentrates (PCs), pooled and stored them.
• Resuspended HLA-A2-negative platelets in HLA-A2-positive plasma.
• Measured HLA-A2 binding using anti-HLA-A2 monoclonal antibodies and flow cytometry over 5 days.

Main Results:

• Increased anti-HLA-A2 antibody binding was observed on HLA-A2-negative platelets, but this was attributed to non-specific binding, as IgG controls showed similar increases.
• Anti-HLA-A2 antibody binding to HLA-A2-positive platelets did not decrease during storage.
• No significant elution or adsorption of HLA class I antigens was detected on platelets in pooled PCs during routine storage.

Conclusions:

• HLA class I compatibility is maintained for platelets in pooled concentrates during storage.
• HLA class I compatible platelets can be stored with incompatible platelets without compromising compatibility for immunized patients.
• Shortened post-transfusion survival due to HLA antigen changes during storage is not expected.