Neumüller J, Tohidast-Akrad M, Fischer M, Mayr W R
Ludwig Boltzmann Institute for Rheumatology and Balneology, Vienna-Oberlaa, Austria.
Vox Sang. 1993;65(3):223-31. doi: 10.1111/j.1423-0410.1993.tb02154.x.
The influence of treatment of platelets with citrate buffer (pH 7.2), chloroquine, or citric acid at pH 3 on the expression of HLA class I antigens and 'thrombocyte-specific' glycoproteins was investigated by means of flow cytometry. After treatment with citric acid at pH 3 and chloroquine, the expression of HLA class I was significantly reduced, while the density of the molecules GPIa/IIa, GPIIb, and GPIIb/IIIa (GP = glycoprotein) carrying 'thrombocyte-specific' antigens was not or only weakly decreased on the surface of the platelets. The use of two monoclonal antibodies (HC-10 and HC-A2) against the native heavy chain of the HLA class I molecule revealed that 'antigen stripping' with chloroquine or citric acid does not affect the entire molecule: only the beta 2-microglobulin is cleaved, or only some epitopes on the heavy chain are altered by this procedure. The treatment with citric acid yielded better results with respect to the removal of HLA class I activity and the preservation of 'thrombocyte-specific' glycoproteins. The presence of the heavy chain of HLA class I molecules on the surface of platelets after treatment with citric acid and chloroquine confirms the hypothesis that platelets--like nucleated cells--bear HLA class I antigens inserted in the cell by a cytoplasmic and a transmembrane domain.
通过流式细胞术研究了用柠檬酸盐缓冲液（pH 7.2）、氯喹或pH 3的柠檬酸处理血小板对HLA I类抗原和“血小板特异性”糖蛋白表达的影响。用pH 3的柠檬酸和氯喹处理后，HLA I类的表达显著降低，而携带“血小板特异性”抗原的分子GPIa/IIa、GPIIb和GPIIb/IIIa（GP = 糖蛋白）在血小板表面的密度未降低或仅轻微降低。使用两种针对HLA I类分子天然重链的单克隆抗体（HC-10和HC-A2）表明，用氯喹或柠檬酸进行“抗原剥离”不会影响整个分子：只有β2-微球蛋白被切割，或者该过程仅改变重链上的一些表位。就去除HLA I类活性和保留“血小板特异性”糖蛋白而言，用柠檬酸处理产生了更好的结果。用柠檬酸和氯喹处理后血小板表面存在HLA I类分子的重链，证实了血小板——与有核细胞一样——通过细胞质和跨膜结构域在细胞中携带插入的HLA I类抗原这一假说。
