Morell A, Skvaril F, Noseda G, Barandun S
Clin Exp Immunol. 1973 Apr;13(4):521-8.
The metabolism of the two subclasses of IgA was investigated in fourteen turnover studies in individuals with normal immunoglobulin serum concentrations. Differences in the catabolism of radioiodinated IgA1 and IgA2 myeloma proteins were found. The average biologic half-life was 5·9 days for IgA1 and only 4·5 days for IgA2. Fractional catabolic rates were 24% of the intravascular pool per day for IgA1 and 34% for IgA2. The intravascular compartment contained approximately 55% of the total body pools of both IgA subclasses. The mean IgA1 serum concentration in the individuals used for turnover studies was 2·3 mg/ml, the mean IgA2 level was 0·32 mg/ml. Synthetic rates of 24 mg/kg per day for IgA1 and 4·3 mg/kg per day for IgA2 were calculated. The low serum concentration of IgA2 results mainly from this low synthetic rate. The fractional catabolic rate of IgA2 is higher than that of IgA1. This further increases the difference between the serum concentrations of the two IgA subclasses. Quantitative determinations of both IgA subclasses were made in twenty-four sera of young male adults. The mean concentrations were 1·81 mg/ml for IgA1 and 0·22 mg/ml for IgA2.
在14项针对免疫球蛋白血清浓度正常个体的周转率研究中，对两类IgA的代谢情况进行了调查。发现放射性碘化IgA1和IgA2骨髓瘤蛋白的分解代谢存在差异。IgA1的平均生物学半衰期为5.9天，而IgA2仅为4.5天。IgA1的分解代谢率为每天血管内池的24%，IgA2为34%。血管内部分约占两类IgA全身池总量的55%。用于周转率研究的个体中，IgA1的平均血清浓度为2.3mg/ml，IgA2的平均水平为0.32mg/ml。计算得出IgA1的合成率为每天24mg/kg，IgA2为每天4.3mg/kg。IgA2血清浓度低主要是由于其合成率低。IgA2的分解代谢率高于IgA1。这进一步加大了两类IgA血清浓度的差异。对24名年轻男性成年人的血清进行了两类IgA的定量测定。IgA1的平均浓度为1.81mg/ml，IgA2为0.22mg/ml。
