抗体阴性重症肌无力发病与凝集素之间关系研究

A study of the relationship between lectins and acetylcholine receptor antibody(AChR ab) negative myasthenia gravis

借助研究抗体阴性重症肌无力（ＭＧ）发病与凝集素之间的关系，以阐明其发病过程是否与凝集素有关。方法观察伴刀豆球蛋白Ａ（ＣｏｎＡ）和麦胚凝集素（Ｔｒｉｔｉｃｕｍ）及其凝集素－糖复合物对ＴＥ６７１细胞表达的乙酰胆碱受体（ＡＣｈＲ）功能的作用，以及对α－ＢｕＴｘ结合试验的影响。结果有两种凝集素对ＡＣｈＲ功能均有抑制作用，抑制率（％）分别为５４±１４（ｎ＝１１）和４７±１６（ｎ＝１０），此作用可被３种糖抑制，抑制率（％）分别为：９５±５（ｎ＝５）和８４±８（ｎ＝５）；６９±６（ｎ＝４）和６５±５（ｎ＝４）；３９±４（ｎ＝５）和５７±６（ｎ＝５）；ＣｏｎＡ抑制α－ＢｕＴｘ结合试验，而Ｔｒｉｔｉｃｕｍ则不能。结论Ｔｒｉｔｉｃｕｍ和抗体阴性ＭＧ患者非ＩｇＧ部分对ＡＣｈＲ功能和α－ＢｕＴｘ结合试验的作用类同或一致，表明抗体阴性ＭＧ患者非ＩｇＧ部分中的内源性Ｔｒｉｔｉｃｕｍ样糖蛋白在其发病过程中起重要作用。

Objective Effects of lectins (Con A and Triticum) on the acetylcholine receptor(AChR) function and alphabungaratoxin(alpha BuTx) binding were studied to reveal if lectins involve in causing AChRab negative myasthenia gravis(seronegative MG) symptoms. Method AChR function in TE 671 cell line and alpha BuTx binding were tested after incubating cells with lectins and their complexes preincubated with sugars, respectively. Results showed that Con A inhibited AChR function on the average of 54 0%. Triticum showed similar inhibition of 47%. Both were in a time and dose dependent manner. In addition, sugars prevented Con A and Triticum from their inhibiting function of AChR on the average of 95% and 84%, 69% and 65% and 39% and 57%, respectively. Furthermore, Con A inhibited alpha BuTx binding to AChR. Triticum showed no such an effect. Conclusion Con A and Triticum by binding to glycoprotein on the AChR surface inhibit the AChR function. It seems Con A binds to the alpha BuTx binding site on the AchR, whereas Triticum most possibly binds to AChR or cell membrane rather than binding to the alpha BuTx binding site. The effects of triticum on the AChR function and alpha BuTx binding were similar to those of our previous studies that the non IgG fractions prepared from seronegative MG plasmas inhibited the AChR function and alpha BuTx binding, suggesting triticum like endogenous glycoprotein might play a crucial role in seronegative MG.