Kulberg A J, Evnin D N, Tarkhanova I A
Immunology. 1976 May;30(5):715-22.
The serum of partially hepatectomized rabbit taken 4 h after operation possessed the proerty of enhancing the immune response to sheep red blood cells (SRBC) in homologous recipients. An exhaustive absorption of the serum with SRBC stromata did not affect its adjuvant-like activity indicating that an active factor augmented the immune response non-specifically. It was shown that the serum of partially hepatectomized rabbits contained a 5-2S IgG fragment antigenically related to peptic F(ab')2 fragment. The i.v. injection of this fragment together with SRBC into rabbits resulted in enhancement of PFC response and haemagglutinin production. Similar enhancing effect was produced by peptic F(ab')2 fragment obtained from rabbit IgG devoid of anti-SRBC antibodies. Sera of partially hepatectomized rabbits did not contain F(ab')2-like fragments and failed to enhance the immune response if the animals were treated with proteinase inhibitor ('Trasylol'), indicating that the fragment was a cetabolic product of IgG. The results are interpreted in terms of regulation of immunoglobulin synthesis by a split product of autologous IgG.
术后4小时采集的部分肝切除兔子的血清具有增强同源受体对绵羊红细胞（SRBC）免疫反应的特性。用SRBC基质对血清进行彻底吸收并不影响其佐剂样活性，这表明一种活性因子非特异性地增强了免疫反应。结果表明，部分肝切除兔子的血清含有一种5-2S IgG片段，其抗原性与胃蛋白酶F(ab')2片段相关。将该片段与SRBC一起静脉注射到兔子体内可增强PFC反应和血凝素产生。从不含抗SRBC抗体的兔IgG中获得的胃蛋白酶F(ab')2片段也产生了类似的增强作用。如果用蛋白酶抑制剂（“抑肽酶”）处理动物，部分肝切除兔子的血清中不含F(ab')2样片段，也无法增强免疫反应，这表明该片段是IgG的代谢产物。这些结果是根据自体IgG的裂解产物对免疫球蛋白合成的调节来解释的。
