Acid elution of platelets class I human leukocyte antigen (HLA) antigens is considered as a strategy for production of HLA-eluted platelets for clinical use. In this study, we investigated the effects of acid treatment for the removal of class I HLA antigens on platelet activation, apoptosis and aggregation, and to evaluate the optimal elution condition and the feasibility of clinical application of the acid-elution technique. In vitro apheresis platelets from healthy volunteers were treated with various PH levels the citric acid solution (pH = 2.0, 3.0, 5.0, 7.0) at 0°C for 10 min. Expression of class I HLA antigens and P-selectin (CD62P) on platelet surface were analyzed by multicolor flow cytometry. The proportion of early apoptotic platelets was detected by Annexin V staining. The maximum platelet aggregation rate was determined by the electrical impedance aggregometry. Results showed that the expression of platelets class IHLA antigens decreased with the reduction of pH value accompanied by increase of CD62P expression and early apoptosis (Annexin V expression). When compared with phosphate buffered saline (PBS) treated platelets, platelets after elution with citric acid at pH 3.0 had significantly decreased expression of class IHLA antigens and the aggregation was not impaired, although the CD62P expression and early apoptosis were significantly increased. These results indicates that elution of platelets with citric acid at pH 3.0 can be use as an attempt to product HLA-eluted platelets for clinical use.
Key words: Platelet, human leukocyte antigen (HLA), CD62P, apoptosis, acid elution.
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