Alpha7 acetylcholine receptor autoantibodies are rare in sera of patients diagnosed with schizophrenia or bipolar disorder

The α7 acetylcholine receptor (AChR) has been linked with the onset of psychotic symptoms and we hypothesized therefore that it might also be an autoimmune target. Here, we describe a new radioimmunoassay (RIA) using iodine 125-labelled α-bungarotoxin and membrane extract from transfected HEK293 cells expressing human α7 AChR. This RIA was used to analyze sera pertaining to a cohort of 711 subjects, comprising 368 patients diagnosed with schizophrenia spectrum disorders, 140 with bipolar disorder, 58 individuals diagnosed of other mental disorders, and 118 healthy comparison subjects. We identified one patient whose serum tested positive although with very low levels (0.2 nM) for α7 AChR-specific antibodies by RIA. Three out of 711 sera contained antibodies against iodine 125-labelled α-bungarotoxin, because they precipitated with it in the absence of α7 AChR. This first evidence suggests that autoantibodies against α7 AChR are absent or very rare in these clinical groups.α7烟碱型乙酰胆碱受体（α7 acetylcholine receptor, AChR）已被证实与精神病性症状的发病相关，据此我们提出假设：该受体亦可作为自身免疫攻击的靶标。本研究报道了一种新型放射免疫分析法（radioimmunoassay, RIA），该方法以碘-125标记的α-银环蛇毒素作为标记物，并使用表达人源α7 AChR的转染HEK293细胞膜提取物作为检测基质。我们采用该RIA对711名受试者的血清样本进行了检测分析，受试者队列涵盖368名精神分裂症谱系障碍确诊患者、140名双相情感障碍患者、58名其他精神障碍确诊个体，以及118名健康对照受试者。检测结果显示，仅1名患者的血清呈α7 AChR特异性抗体阳性，但其抗体水平极低（0.2 nM）。在全部711份血清样本中，另有3份样本可检出针对碘-125标记的α-银环蛇毒素的抗体，这是因为在无α7 AChR存在的条件下，这些抗体可与该毒素发生沉淀反应。本研究的初步证据显示，在上述临床组别中，针对α7 AChR的自身抗体几乎不存在或极为罕见。