Vos G H, Marimuthu T, Vos D
S Afr Med J. 1979 Nov 3;56(19):751-56.
Evidence for the association of Fab (antigen-binding) fragments of IgG and antibodies directed against receptors of these fragments (Fab' and F(ab)2) has been found in patients and asymptomatic carriers of hepatitis B antigen. Fab fragments of IgG are often detected in hepatitis B surface antigen (HBsAg)-positive sera where the intensity of antibody activity to these determinants is significantly reduced. The formation of strong antibodies to Fab fragments is often observed in association with the presence of hepatitis B surface antibodies (HBsAb). Comparative studies show that the appearance of Fab fragments in HBsAg-positive sera is not linked to the presence of hepatitis e antigen. This observation was supported by the finding of autologous Fab fragments of IgG in e antibody-positive sera. It was also established that the amount of Fab fragment in the serum is closely associated with the detection of high HBsAg titres. Preliminary investigations suggest that the Fab fragments of IgG detected in the serum of HBsAg-positive patients represent in vivo-digested HBsAb attached to the surface membrane of virus B particles. Further studies are in progress to determine the relationship of Fab fragments with a variety of other immunological events, especially the role of liver enzymes in the cleavage of intact antibodies.
在乙肝抗原患者和无症状携带者中发现了IgG的Fab（抗原结合）片段与针对这些片段受体（Fab'和F(ab)2）的抗体之间存在关联的证据。在乙肝表面抗原（HBsAg）阳性血清中经常检测到IgG的Fab片段，而针对这些决定簇的抗体活性强度显著降低。在存在乙肝表面抗体（HBsAb）的情况下，经常观察到针对Fab片段的强抗体形成。比较研究表明，HBsAg阳性血清中Fab片段的出现与戊型肝炎抗原的存在无关。在e抗体阳性血清中发现IgG的自体Fab片段支持了这一观察结果。还确定血清中Fab片段的量与高HBsAg滴度的检测密切相关。初步研究表明，在HBsAg阳性患者血清中检测到的IgG的Fab片段代表附着在B型病毒颗粒表面膜上的体内消化的HBsAb。正在进行进一步研究以确定Fab片段与各种其他免疫事件的关系，特别是肝酶在完整抗体裂解中的作用。
