目的  探讨COVID-19康复者恢复期血浆及COVID-19静注人免疫球蛋白（human intravenous immunoglobulin，IVIG）（COVID-19-IVIG）IgG及亚类的水平。方法  选择2020年2月至3月国药集团武汉血液制品有限公司采集的COVID-19康复者恢复期血浆及制备的COVID-19-IVIG作为研究组，选择健康者单采血浆及IVIG作为对照组。采用免疫比浊法检测并比较免疫球蛋白(IgG、IgA、IgM）及IgG亚类水平。分析COVID-19-IVIG中IgG亚类与其他蛋白之间的相关性。结果  健康者单采血浆的IgG3、IgG4水平显著高于康复者恢复期血浆（P<0.05），但IgG1、IgG2水平差异无统计学意义（P>0.05）。恢复期血浆IgM水平与血型﹝相关系数（r）=0.649﹞、抗体效价（r=0.696）呈正相关性（P<0.05），IgG1（r=0.745）、IgG2（r=0.952）水平与IgG呈正相关（P<0.05）。COVID-19-IVIG的IgG1/显著高于康复者恢复期血浆（t=3.633，P<0.05），而IgG4/显著低于康复者混合血浆（t=-4.899，P<0.05），两组间IgG2/ 和IgG3/ 差异无统计学意义（t值分别为-0.974和-0.280，P值均大于0.05）。COVID-19-IVIG与IVIG的IgG亚类分布差异无统计学意义（P>0.05）。在COVID-19-IVIG中，仅IgG2水平与α2-巨球蛋白呈负相关（P<0.05）。结论  恢复期血浆IgG亚类水平与健康者单采血浆有一定差异。COVID-19-IVIG制备过程中存在IgG亚类水平的变化，COVID-19-IVIG IgG亚类齐全，与IVIG IgG亚类水平相近。COVID-19-IVIG对治疗COVID-19患者具有积极意义。

Objective  To investigate the levels of IgG and its subclasse in convalescent plasma of COVID-19 and COVID-19 human intravenous immunoglobumin (IVIG) (COVID-19-IVIG). Methods  The convalescent plasma collected and COVID-19-IVIG made by Sinopharm Wuhan Plasma-derived Biotherapies Co., Ltd. from February to March 2020 were selected as study group, and healthy human plasma and IVIG were selected as control group. Immunonephelometry was used to detect and compare IgG, IgA, IgM levels and the IgG subclass level of the samples. The correlations of IgG subclasses and other proteins in COVID-19-IVIG were analyzed. Results  The levels of IgG3 and IgG4 in healthy human plasma were significantly higher than those in convalescent plasma (P<0.05), but there was no significant difference in IgG1 and IgG2 levels (P>0.05). In convalescent plasma, the level of IgM was positively correlated with blood type[correlation coefficient(r)=0.649] and antibody titer （r=0.696）(P<0.05), while IgG1(r=0.745) and IgG2(r=0.952) levels were positively correlated with IgG (P<0.05). COVID-19-IVIG IgG1 / was significantly higher than the convalescent plasma (t=3.633, P<0.05), while IgG4 / was lower (t=-4.899, P<0.05), and there was no significant difference in IgG2 / (t=-0.974) and IgG3/(t=-0.280) (P>0.05). There was no significant difference in the distribution of IgG subclasses between COVID-19-IVIG and IVIG (P>0.05). In COVID-19-IVIG, only IgG2 was negatively correlated with α2-macroglobulin (P<0.05). Conclusion  The convalescent plasma and healthy human plasma has similar distribution of IgG subclasses. During the preparation of COVID-19-IVIG, there is a change in the distribution level of IgG subclasses. The IgG subclasses were complete, and their levels are similar to IVIG.