抗人层粘连蛋白Fab‘的制备

用ＤＥＡＥ纤维素ＤＥ－５２反相吸附纯化抗人层粘连蛋白（ＬＮ）ＩｇＧ，ＩｇＧ回收率达１１．６ｍｇ／ｍｌ血清。胃蛋白酶消化ＩｇＧ成Ｆ（ａｂ＇）２，再用１０ｍｍｏｌ／Ｌ２－巯基乙醇３７℃反应９０ｍｉｎ还原成Ｆａｂ＇，回收率约８１％，放免效价为１：３５００。测得纯化的ＩｇＧ、Ｆ（ａｂ＇）２及Ｆａｂ＇分子量分别为１５００００、９００００、４５０００，与理论植相近。放免检测中用Ｆａｂ＇取代抗血清可纠正对血清Ｌ     

FPLC纯化单克隆抗体（Fab＇）_2片段

作者采用ＤＥＡＥ－４０ＨＲ阴离子交换色谱柱，在Ｗａｔｅｒｓ６５０Ｅ快速蛋白液相色谱系统（ＦＰＬＣ）建立了抗肝癌单克隆抗体（ＨＡｂ１８）Ｆ（ａｂ＇）２片段的快速纯化方法。该法是将ＭｃＡｂ用胃蛋白酶消化１８ｈ后，上阴离子交换色谱柱纯化，用ｐＨ７．５１０ｍｍｏｌ／ＬＰＢ洗脱，即得到纯化的Ｆ（ａｂ＇）２．一次纯化周期仅需２５ｍｉｎ，一次上样量１２０～１６０ｎｇ蛋白，Ｆ（ａｂ＇）２得率为３４％，回收率为５１％。经ＳＤＳ－ＰＡＧＥ测定纯度大于９５％，免疫荧光法测定活性为１：４０００．该法操作简单、快速、实用性强，不需要高档次的色谱仪，只要有一台核酸／蛋白检测仪便可进行纯化，是实验室纯化Ｆ（ａｂ＇）２的理想方法．     

抗rhTNF-α单克隆抗体F(ab′)_2片段的制备

采用胃酶消化抗ｒｈＴＮＦ－αＭｃＡｂ制备了其Ｆ（ａｂ′）２片段。对胃酶消化的时间，酶／抗体的比例及片段回收率等条件做了比较。结果显示，胃酶在ｐＨ４．２于３７℃消化１８ｈ，可制备出完整的Ｆ（ａｂ′）２片段；非还原型ＳＤＳ－ＰＡＧＥ发现，有９０％以上的ＩｇＧ被降解为Ｆ（ａｂ′）２片段；Ｓ－２００层析柱纯化Ｆ（ａｂ′）２片段的回收率达４５％；双抗体夹心竞争抑制ＥＬＩＳＡ法测定Ｆ（ａｂ′）２片段的竞争抑制效价为２．６×１０７。中和Ｌ９２９细胞毒活性试验的结果表明，１４８ｎｇ的Ｆ（ａｂ′）２片段可中和１个单位ｒｈＴＮＦ－α的细胞毒作用。     

兔抗人ClqIgG（Fab＇）_2的制备及鉴定

本文利用硫酸铵盐析及ＤＥＡＥ纤维素层析提取兔抗人ＣｌｑＩｇＧ．经胃蛋白酶消化及ＳＰＡ－Ｓｅｐｌｉａｒｏｓｅ４Ｂ层析，制备了兔抗人ＣｌｑＩｇＧ（Ｆａｂ＇）＿２．ＳＤＳ－ＰＡＧＥ分析分子量为９３ＫＤ；经Ｃｌｑ－ＥＬＩＳＡ滴定其效价为１０￣（－４）．与人ＩｇＧ无交叉反应；当该制剂预先经人Ｃｌｑ处理后，阻断其与Ｃｌｑ特异结合的能力，在合适的条件下可抑制Ｃｌｑ与Ｒａｊｉ细胞上ＣｌｑＲ的结合。表明用该法制备的兔抗人ＣｌｑＩｇＧ（Ｆａｂ＇）＿２具有较好的纯度及特异性，可用于ＣｌｑＲ功能的研究。     

胃肠道癌患者血清中抗癌胚抗原(CEA)抗体的检测及意义

目的：探讨循环中抗癌胚抗原（ＣＥＡ）特异性抗体的情况，评价ＣＥＡ及抗体的联合检测在胃肠道癌诊断中的作用。方法：用放免法检测血清中 ＣＥＡ含量，用酶联免疫吸附法（ＥＬＩＳＡ）检测抗 ＣＥＡ ＩｇＧ抗体，用竞争抑制法检测抗体的特异性。结果：胃肠道癌患者血清 ＣＥＡ含量升高者（≥１５ ｎｇ／ｍｌ）为 ３０．９％（２１／６８），抗 ＣＥＡ ＩｇＧ抗体阳性者为３５．３％（２４／６８），ＣＦＡ及抗 ＣＥＡ抗体的联合检测可使阳性率提高到５４．３％（３７／６８）；胃肠道良性疾病患者（多发性息肉、溃疡、胰腺炎等）血清ＣＥＡ升高者为３．３％（１／３０），抗 ＣＥＡ　ＩｇＧ抗体阳性者为 ３．３％（１／３０）；健康对照组血清 ＣＥＡ升高者为 ０，抗 ＣＥＡ ＩｇＧ抗体阳性者为 ２．５％（１／４０）。结论：胃肠道癌患者血清中抗癌胚抗原（ＣＥＡ）抗体的检出率较高，这些抗体可作为胃肠道癌的一种肿瘤标志物。     

多抗F（ab＇）_2－ELISA测定人血清抗TG－Ab_2及意义

为了克服单抗测定甲状腺球蛋白独特型抗体（抗ＴＧ－Ａｂ＿２）的局限性，便于常规检测，我们建立了兔抗ＴＧ多克隆抗体的Ｆ（ａｂ＇）＿２－ＥＬＩＳＡ测定人血清中的抗ＴＧ－Ａｂ＿２．结果其抗ＴＧ－Ａｂ＿２阳性率：甲亢（Ｇｒａｖｅ＇３）为９．９％（７／７１），桥本氏甲状腺炎为４４．４％（４／９），甲状腺瘤为１６．７％（３／１８），ＳＬＥ为９．５％（４／４２），类风湿性关节炎为０％（０／３２），正常人为０％（０／３５）。     

抗人IgGFc和Fab单克隆抗体的鉴定及应用

本文将采用木瓜蛋白酶水解和ＳＰＡ－Ｓｅｐｈａｒｏｓｅ４Ｂ柱亲和层析等手段获得的人ＩｇＧＦｃ和Ｆａｂ，以抗人ＩｇＧＦｃ和抗人ＩｇＧＦａｂ单抗为参比品（Ｓｉｇｍａ）．鉴定了细胞库中抗人ＩｇＧ系列的部分细胞林，得到分泌特异性抗人ＩｇＧＦｅ和抗人ＩｇＧＦａｂ单抗的细胞各一株。在此基础上。应用抗人ＩｇＧＦｃ及抗人ＩｇＧＦａｂ单抗分别制备了Ｓｅｐｈａｒｏｓｅ４Ｂ亲和层析柱，纯化了酶解的人ＩｇＧＦｃ和Ｆａｂ。经ＥＬＩＳＡ法鉴定，相互间无交叉反应。同时用此方法还制备了人抗ＨＢｅＦａｂ，并将此Ｆａｂ标记过氧化物酶。配制ＨＢｅＥＬＩＳＡ诊断盒，证明其生物学活性未受影响，而且消除了类风湿因子引起的ＨＢｅＡｇ假阳性现象。     

人源性抗HBsAg单克隆抗体Fab片段的表达与纯化

对已筛选到的人源性抗ＨＢｓＡｇ特异性噬菌体抗体基因文库进行表达研究，将特异性噬粒转化大肠杆菌ＸＬ１－Ｂｌｕｅ，反复冻溶法制备可溶性Ｆａｂ片段。免疫印迹实验表明大肠杆菌质周腔内有可溶性Ｆａｂ片段的表达。制备羊抗人ＩｇＧ Ｆａｂ抗血清，建立抗人ＩｇＧ Ｆａｂ抗体－Ｓｅｐｈａｒｏｓｅ ４Ｂ亲和层析柱，纯化Ｆａｂ片段。ＳＤＳ－ＰＡＧＥ显示纯化的Ｆａｂ达免疫纯，点印迹法表达纯化后的Ｆａｂ片段具有中和ＨＢｓＡ     

阴离子交换FPLC制备级纯化单克隆抗体

作者采用ＤＥＡＥ－４０ＨＲ阴离子交换柱。在快速蛋白液相色谱系统（ＦＰＬＣ）建立了ＩｇＧ类单克隆抗体制备级纯化方法。该法是将ＭｃＡｂ腹水经５０％饱和硫酸铵盐析粗分离后，再用阴离子交换色谱纯化，一次上样量相当于８０～１００ｍｌ腹水。可得纯化ＭｃＡｂ５００～６００ｍｇ，得率为６～７ｍｇ／ｍｌ腹水，回收率为５７～６７％．一次纯化周期仅需４５ｍｉｎ。经ＳＤＳ－ＰＡＧＥ检测ＭｃＡｂ纯度为９５％，ＡＢＣ染色法测定ＭｃＡｂ活性为１：２００００（３．１３×１０－１０ｍｏｌ／Ｌ）．     

兔抗人C1qIgG（Fab‘）2的制备及鉴定

本文利用硫酸铵盐析及ＤＥＡＥ纤维素层析提取兔抗人Ｃ１ｑＩｇＧ．经胃蛋白酶消化及ＳＰＡ－Ｓｅｐｈａｒｏｓｅ ４Ｂ层析，制备了兔抗人ｃ１ｑＩｇＧ（Ｆａｂ＇）２．ＳＤＳ－ＰＡＧＥ分析分子量为９３ＫＤ；经Ｃ１ｑＥＬＩＳＡ滴定其效价为１０＾－４，与人ＩｇＧ无交叉反应；当该制剂预先经人Ｃ１ｑ的处理后，阻断其与Ｃ１ｑ特异结合的能力，在合适的条件下可抑制Ｃ１ｑ和Ｒａｊｉ细胞上Ｃ１ｑＲ的结合。表明用该法制备的兔抗人     

Fab’酶标法用于高灵敏ELISA的研究Ⅰ.抗人肝癌铁蛋白Fab’的制备与鉴定

用硫酸钠-DEAE纤维素层析法从兔抗人肝癌铁蛋白的血清中提纯相应的IgG,回收率为68％。当IgG浓度为8mg/ml时,免疫效价为1:64。再用胃蛋白酶将IgG消化成F(ab′)_2,回收率为65％,分子量为92,000,效价较IgG略有降低。F(ab′)_2用10mM巯基乙醇在pH6.0、37℃的条件下反应1.5小时而被还原成Fab′,回收率达74％,分子量为46,000。Fab′分子中的巯基数为0.95～1.28,平均1.14和理论值1.0接近,符合酶标的要求。若延长还原时间将导致巯基数/分子增加,提示轻-重链间的二硫链亦被还原而可能导致抗体活力的丧失。     

Further studies of the adjuvant properties of homologous IgG split products: mode of action of F(ab'')2 and related fragments.

Peptic bivalent and monovalent Fab' fragments as well as F(ab')2 fragment from a purified rabbit anti-DNP antibody were equally effective in enhancement of the immune response to SRBC. In contrast, the papain Fab fragment of normal IgG possessed a considerably lower enhancing activity. These data indicate that the effector site(s) controlling the adjuvant activity of F(ab')2 and related fragments is structurally distinct from the antibody active site(s) within the fragment molecule, and is located in C-terminal region of the heavy chain Fd fragment. When F(ab')2 fragment was injected into rabbits together with the proteinase inhibitor Trasylol it failed to enhance the immune response to SRBC. Furthermore, Trasylol interferes with the ability of F(ab')2 or Fab' fragment to activate the complement system both in vivo and in vitro. This, together with the observation that F(ab')2 fragments enhance the response to T-dependent antigens (SRBC and bovine gamma globulin) but fail to augment the response to LPS, suggests that these fragments may operate via activation of complement and thereby influence indirectly the reactivity of complement receptor B cells.     

Alternative Non-Immune F(ab')2-Mediated Immunoglobulin Binding to Group C and G Streptococci

We tested 140 bacterial strains representing 19 different species for binding or purified radiolabelled F(ab')₂ fragments prepared by pepsin digestion of polyclonal and monoclonal human IgG. Both polyclonal and monoclonal F(ab')₂ fragments showed positive binding to group C and G streptococci with maximum uptake levels of 50% and 85%. Binding was obtained both with fresh bacteria and with organisms stabilized by heat treatment. F(ab')₂ fragments of two human IgG1 myeloma proteins with anti-staphylolysin specificity showed a similar binding pattern. IgG present in normal human serum inhibited the uptake of F(ab')₂ fragments, whereas albumin and fibrinogen and purified Fc fragments prepared by papain digestion of polyclonal IgG and monoclonal IgG1 did not show such capacity. Fourteen human myeloma proteins representing IgA, IgM and the four IgG subclasses were tested for inhibiting capacity. Reactivity was noted with at least one myeloma protein within each IgG subclass but not with IgA or with IgM monoclonal proteins. Normal rabbit serum was as inhibitory as normal human serum, whereas dog serum was less reactive. These data demonstrate that group C and G streptococci carry a heat-stable surface component interacting with the F(ab')₂ portion of the IgG molecule. The results suggest that the reactive site on the immunoglobulin molecule may reside in the more constant part of the variable domain. This new reactivity is different from the previously known non-immune reaction involving the IgG Fc portion. This alternative non-immune reactivity is analogous to but distinct from the alternative protein A reaction in Staphylococcus aureus .     

Neutralization of tetanus toxin by human and rabbit immunoglobulin classes and subunits

This investigation found that the human antibody class of importance in neutralizing tetanus toxin in mice was IgG, and that toxin neutralization was retained by the F(ab')2 and Fab' subunits of the human IgG class. Although human IgM and IgA classes appeared to neutralize tetanus toxin at very low levels, evidence was obtained that this neutralization was probably due to IgG contamination. Human Fabmu isolated from the IgM class did not neutralize tetanus toxin. Human antibodies of the IgG, IgM and IgA classes reacted with tetanus toxoid in the indirect haemagglutination (HA) test with IgG giving the highest HA titre. Rabbit antibodies of the IgG class also neutralized tetanus toxin, with neutralization being retained by the F(ab')2 and Fab' subunits of the rabbit IgG class. Absorption of several rabbit antisera to tetanus toxoid with goat-antirabbit Fc which is specific for absorption of IgG from antiserum, rendered them incapable of neutralizing tetanus toxin.     

疏水层析法和凝胶过滤法分离HI47抗CD20 F(ab'''')2之比较

目的　比较疏水层析和凝胶过滤两种方法分离纯化HI4 7抗CD2 0F(ab’) 2 的优缺点。方法　采用亲和层析柱protein G对发酵菌体裂解液进行粗纯化,分别采用疏水层析法和凝胶过滤法进行抗CD2 0F(ab’) 2 的分离纯化:疏水层析采用梯度洗脱,80 %B液洗脱2 0min ,10 0 %B液洗脱30min ;凝胶过滤以5 0mmol LPB缓冲液(pH 7.0 ) ,0 .8mL min洗脱4h。结果　粗纯化产物主要含F(ab’) 2 、Fab’,含量分别为19.6 %、5 9.7%。采用疏水层析法1h即可完成分离,F(ab’) 2 回收率为6 7% ,纯度为89.3% ;凝胶过滤4h完成分离,F(ab’) 2 回收率为6 5 % ,纯度为90 .5 %。FACS结果表明,两者结合Raji细胞的阳性率分别为99.93%和99.97%。结论　疏水层析分离纯化抗CD2 0F(ab’) 2 简单、快速、回收率高、纯度高,适用于大规模的工业化生产。     

Identification of an Fc receptor for IgG1 and IgG2 on guinea-pig polymorphonuclear leukocytes

Ovalbumin (OA)-complexed guinea-pig IgG1 and IgG2 antibodies were found to bind to homologous polymorphonuclear leukocytes (PMNs). As these bindings are assumed to be mediated by certain Fc receptors (FcRs) for IgG1 and IgG2, the variety and properties of the FcRs on the cells were investigated by the use of two monoclonal antibodies to guinea-pig macrophage FcRs which were prepared by Shimamura T. et al., 1987 (Molec. Immun. 24, 67-74): VI A2 IgG1 to the FcR for IgG1 and IgG2 (FcR1,2) and VII A1 IgG1 to the FcR for IgG2 (FcR2). PMNs were shown to bind the Fab' of VI A2 IgG1 (VI A2 Fab') by flow cytofluorometry, suggesting that the cells possess a certain FcR which cross-reacts antigenically with macrophage FcR1,2. In fact, VI A2 Fab' inhibited completely the binding of OA-complexed IgG1 antibody to the cells. When the FcR was isolated by affinity chromatography on the F(ab')2 of VI A2 IgG1 coupled to Sepharose, it gave a 55,000 mol. wt band on sodium dodecylsulfate-polyacrylamide gel electrophoresis, as in the case of macrophage FcR1,2. The number of the FcR molecules per PMN cell was estimated to be 2 X 10(4) by measuring the binding of 125I-VI A2 Fab'. The binding of OA-complexed IgG2 antibody to PMNs was also inhibited with VI A2 Fab', but partially. This finding indicates that the FcR bound by VI A2 Fab' may be an FcR1,2 which is able to bind both OA-complexed IgG1 and IgG2 antibodies, and also that PMNs possess another FcR, namely FcR2 which binds IgG2 antibody alone. The Fab' of VII A1 IgG1 (VII A1 Fab'), on the other hand, did not exhibit any inhibitory activity on the bindings of OA-complexed IgG1 and IgG2 antibodies to PMNs. Since no evidence indicating the binding of VII A1 Fab' to PMN cells was obtained by flow cytofluorometry, the FcR2 of PMNs may be antigenically different from its macrophage counterpart. In conclusion, these results indicate that two distinct types of FcR for IgG isotypes exist on guinea-pig PMN cells: FcR1,2 similar to macrophage FcR1,2, and FcR2 distinct from macrophage FcR2.     

Characterization of a new monoclonal anti-Fc gamma RII antibody, AT10, and its incorporation into a bispecific F(ab')2 derivative for recruitment of cytotoxic effectors.

Fc gamma RII (CDw32) on monocytes is capable of triggering both phagocytosis and lysis of chick red blood cells (CRBC) coated with antibody of the appropriate isotype. In this report we describe the production and characterization of a mouse monoclonal IgG1 antibody specific for Fc gamma RII and compare its activity in binding studies, tissue distribution and redirected cellular cytotoxicity (RCC), with the previously identified anti-Fc gamma RII antibodies KB61 and IV.3. Immunohistochemical and flow cytometry analyses demonstrated that AT10 binds very strongly to Fc gamma RII on normal monocytes, but only weakly to that expressed on lymphocytes. This pattern does not correspond to the staining seen with either KB61 or IV.3, and appears to give an intermediate profile. The binding constant (Ka) for the Fab' fragment of AT10 was calculated at 5.3 x 10(8) M-1, four times higher than that for KB61 (1.4 x 10(8) M-1). Bispecific F(ab')2 antibodies were constructed from Fab' fragments of AT10 or KB61 thioether-linked to Fab' from an anti-CRBC monoclonal antibody. These bispecific derivatives directed monocyte cytotoxicity against CRBC as efficiently as either a monoclonal or polyclonal anti-chick erythrocyte antibody. The bispecific F(ab')2 antibodies had a distinct advantage over the conventional reagents, in that they were not blocked in the presence of human Fc gamma at 3.5 mg/ml (a concentration comparable with that provided by IgG in serum). Therefore, bispecific derivatives constructed with the high affinity anti-Fc gamma RII antibody, AT10, may be used as therapeutic reagents for targeting tumour cell lysis in vivo.     

Demonstration of the existence of two distinct Fc receptors for IgG isotypes on guinea-pig macrophages by the use of monoclonal antibodies

As reported in a previous paper by the authors (J. Biochem. 99, 227-235, 1986), the Fab' of a monoclonal antibody, VIA2 IgG1, prepared by fusion of splenic cells of a mouse immunized with guinea-pig peritoneal macrophages with a myeloma cells line, completely inhibits the binding of ovalbumin (OA)-complexed IgG1 antibody to macrophages, but only partially the binding of OA-complexed IgG2 antibody. Based on these results, it was proposed that the cells have at least two types of Fc receptor (FcR) for homologous IgG isotypes: FcR2 for IgG2 and FcR1.2 for both IgG2 and IgG1, and also that VIA2 IgG1 is anti-FcR1.2 antibody. Thereafter, complete inhibition of the binding of OA-complexed IgG2 antibody to macrophages occurred when the Fab' of another monoclonal antibody, VIIA1 IgG1 was added to the Fab' of VIA2 IgG1, whereas the former did not affect the binding of OA-complexed IgG1 antibody. This effect of the Fab' of VIIA1 IgG1 indicates that VIIA1 IgG1 is a monoclonal antibody capable of selectively blocking the binding of OA-complexed IgG2 antibody to FcR2. When the antigen of VIIA1 IgG1 was isolated by affinity chromatography on the F(ab')2 of the antibody coupled to Sepharose, it gave a single band with a mol. wt of 52,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It moved slightly faster than the FcR1.2 with a mol. wt of 55,000, which was isolated by the use of VIA2 IgG1, and corresponded to the fast moving portion of the broad band of FcRs isolated with OA-complexed IgG2 antibody. These results strongly suggest that VIIA1 IgG1 is a monoclonal antibody to FcR2.     

Antibodies against Fc receptors to aggregated IgG of mouse spleen cells: selective blocking of the receptors of splenocytes and peritoneal macrophages, and abolition of the phagocytosis enhancement produced by the opsonizing IgG antibodies.

The Fc receptors to aggregated IgG of mouse spleen cells were solubilized with Nonidet P-40, absorbed by immune precipitate, and the complex obtained was used to raise anti-Fc receptor antibodies in a rabbit. The antibody and its F(ab')2 fragment inhibit binding of heat-aggregated IgG with mouse spleen cells and peritoneal macrophages. When F(ab')2 from the anti-Fc receptor antibody was absorbed exhaustively with mouse peritoneal macrophages, it still partially inhibited the reaction between aggregated IgG and mouse spleen cells devoid of the adherent cells. These data indicate that the Fc receptors to aggregated IgG which are located on the surface of splenocytes and peritoneal macrophages carry both common and private antigenic determinants. It was also demonstrated that the pretreatment of the macrophages with Fab' from anti-Fc receptor antibody abolished completely the phagocytosis enhancement produced by the IgG opsonins.     

Further studies on the biological properties of guinea-pig IgG1 antibodies. III. Haemolytic efficiency in vitro.

The capacity of non-reciprocally contaminated guinea-pig IgG1 and IgG2 antibodies for sensitizing antigen-coated sheep erythrocytes for lysis was studied in the presence of serial dilutions of normal guinea-pig serum as the source of complement. IgG1 antibodies were highly efficient, provided complement was little diluted and not heated at 56 degrees. Chelation of Ca2+ by EGTA affected lysis of IgG1-sensitized cells by only 50%, while completely blocking lysis of IgG2-sensitized cells. The F(ab')2 fragment of IgG1, in contrast to the F(ab')2 fragment of IgG2, was almost as efficient as the parent antibody.