小鼠抗天花粉蛋白IgE型单抗的酶解及其Fab的制备

研究了ｐａｐａｉｎ及Ｔｒｙｐｓｉｎ裂解小鼠抗天花粉蛋白ＩｇＥ单抗的条件及Ｆａｂ的制备，Ｐａｐａｉｎ和Ｔｒｙｐｓｉｎ两者都可产生Ｆ（ａｂ’）２分子量在１５０￣１６０ｋＤ左右；经Ｐａｐａｉｎ裂解的主要产物中还有Ｆａｂ，分子量７２ｋＤ，可通过凝胶过滤获得纯的Ｆａｂ，而Ｔｒｙｐｓｉｎ裂解物经ＤＴＴ还原、碘乙酰胺烷化虽然也可得到Ｆａｂ’（ｔ），但不易纯化，可见，要制备Ｆａｂ以采用ｐａｐａｉｎ裂解为好，而制备     

普通小麦与东方旱麦草属间杂种的形态和细胞遗传学研究

本文对普通小麦（ＴｒｉｔｉｃｕｍａｅｓｔｉｖｕｍＬ．ｅｖ．Ｆｕｋｕｈｏ,２ｎ＝６ｘ＝４２,ＡＡＢＢＤＤ）与东方旱麦草（Ｅｒｅｍｏｐｙｒｕｍｏｒｉｅｎｔａｌｅ（Ｌ．）Ｊａｕｂ．ｅｔＳｐａｃｈ,２ｎ＝４ｘ＝２８,Ｂ′Ｂ′Ｃ′Ｃ′）属间杂种Ｆ_１进行了形态和细胞遗传学方面的探讨。首先,在形态方面的研究表明：（１）杂种Ｆ_１植株生长旺盛,分蘖力强;（２）绝大部分性状如株高、穗长、芒长等介于双亲之间而呈中间型,少数性状如颖脊、颖壳茸毛可作为鉴别杂种的形态标记;（３）花粉粒空秕、无可染性,花粉高度不育,自交完全不结实。其次,从杂种Ｆ_１的细胞遗传学研究表明：（１）染色体平均构型为：２６．０９Ⅰ＋４．３６Ⅱ＋０．０９Ⅲ,二价体数目从０－７个均有分布,但大多数为棒状二价体;（２）每细胞平均交叉数为４．７８;（３）染色体臂平均配对频率（Ｃ值）为０．１７。由上可知,在普通小麦ＡＢＤ基因组与东方旱麦草Ｂ′Ｃ′基因组之间存在微弱的部分同源关系,或在东方旱麦草基因组中可能存在一种抑制普通小麦Ｐｈ基因作用的抑制因子（ｓｕｐｐｒｅｓｓｏｒ）。     

镉诱导威廉环毛蚓（Pheretima guillelmi）金属硫蛋白的分离纯化…

蚯蚓威廉环毛（Ｐｈｅｒｅｔｉｍａ ｇｕｉｌｌｅｌｍｉ）经皮下注射ＣｄＣｌ２溶液诱导后,整体匀浆,再经热沉淀、乙醇沉淀后,经凝胶过滤ＳｅｐｈａｄｅｘＧ－５０柱层析,得两个镉结合蛋白峰,分子量依次为４３ｋＤ及１９ｋＤ。这两个组份再分别经ＤＥＡＥＳｅｐｈａｒｏｓｅ Ｆａｓｔ Ｆｌｏｗ柱层析,各得三个镉结合蛋白峰。根据光谱学特征、疏基含量及氨基酸组成等分析,表明凝胶过滤第二峰为金属硫蛋白（ＭＴ）,其经ＤＥ     

芹菜韧皮部中的微管蛋白和类动蛋白

用免疫荧光标记和免疫印迹技术,证明芹菜韧皮部中存在微管蛋白和类动蛋白（ｋｉｎｅｓｉｎ－ｌｉｋｅｎｒｏｔｅｉｎ）。微管蛋白分子量约为５５ｋＤ,以微管状态沿筛管长度排列;类动蛋白重链分子量为１００ｋＤ,主要存在于筛管中的无定型颗粒（或聚合物）上。芹菜韧皮部中的类动蛋白,很可能象动物神经细胞中的动蛋白（ｋｉｎｅｓｉｎ）一样,是作为分子马达在物质运输中起作用。     

人早期胎盘绒毛纤维连接蛋白的分离纯化及鉴定

人妊娠５－８周的胎盘绒毛经匀浆后,用２ｍｏ１／Ｌｕｒｅａ－ＰＢＳ提取,通过Ｈｅｐａｒｉｎ－Ｓｅｐｈａｒｏｓｅ４Ｂ亲和柱层析,再经ＳｅｐｈａｒｏｓｅＣＬ－６Ｂ凝胶过滤层析,得到人早期胎盘纤维连接蛋白（ｅａｒｌｙｐｌａｃｅｎｔａｆｉｂｒｏｎｅｃｔｉｎ,ｅｐＦＮ）。经还原及非还原ＳＤＳ－ＰＡＧＥ和免疫印迹电泳分析,ｅｐＦＮ分子量约５００ｋＤ,是由两个２５０ｋＤ亚基组成,与人足月胎盘纤维连接蛋白（ｔｅｒｍｐｌａｃｅｎｔａｆｉｂｒｏｎｅｃｔｉｎ,简称ｔｐＦＮ）相似,而大于人血浆纤维连接蛋白（ｐｌａｓｍａｆｉｂｒｏｎｅｃｔｉｎ,ｐＦＮ）。ｅｐＦＮ与抗人ｐＦＮ抗体及抗人羊水纤维连接蛋白（ａｍｎｉｏｔｉｃｆｌｕｉｄｆｉｂｒｏｎｅｃｔｉｎ,简称ａｍＦＮ）的三个主要功能区单抗均可发生反应。与五种植物凝集素结合力实验表明,ｅｐＦＮ在糖基组成上与ｐＦＮ和ｔｐＦＮ均不相同。     

镉诱导威廉环毛蚓（Pheretima guillelmi）金属硫蛋白的分离纯化及特性研究

蚯蚓威廉环毛（ｐｈｅｒｅｔｉｍａ　ｇｕｉｌｌｅｌｍｉ）经皮下注射ＣｄＣｌ２溶液诱导后,整体匀浆,再经热沉淀、乙醇沉淀后,经凝胶过滤Ｓｅｐｈａｄｅｘ　Ｇ－５０柱层析,得两个镉结合蛋白峰,分子量依次为４３ｋＤ及１９ｋＤ。这两个组份再分别经ＤＥＡＥ　Ｓｅｐｈａｒｏｓｅ　Ｆａｓｔ　Ｆｌｏｗ柱层析,各得三个镉结合蛋白峰。根据光谱学特征、巯基含量及氨基酸组成等分析,表明凝胶过滤第二峰为金属硫蛋白（ＭＴ）,其经ＤＥＡＥ柱层析所得三个峰为ＭＴ三个亚型,Ｎ末端分别为Ｌｙｓ、Ａｌａ、Ａｌａ。     

玉米精细胞及体细胞原生质体表膜蛋白的比较

以低渗冲击法（改良两步法）及Ｐｅｒｃｏｌｌ密度梯度离心,成功分离纯化生活玉米（Ｚｅａｍ ａｙｓ）精细胞;以混合酶解法制备玉米叶原生质体和愈伤组织原生质体;以ＮＨＳ－生物素标记完整精细胞及原生质体表膜蛋白,进行ＳＤＳ－ＰＡＧＥ和Ｗｅｓｔｅｒｎ ｂｌｏｔ,并以辣根过氧化物酶标亲和素检测被标记的表膜蛋白。结果表明,在精细胞中标记蛋白有４ 种,分子量分别为４８、５９、６７、７９ ｋＤ;叶片原生质体中有５ 种,分子量分别为５４、５８、６６、７１、７８ ｋＤ;愈伤组织原生质体中仅有２ 种,分子量６７ 和８０ ｋＤ。其中４８ ｋＤ蛋白为精细胞所特有,５４ ｋＤ 和７１ ｋＤ蛋白为叶片细胞所特有     

豆薯种子中两种蛋白质的分离纯化及其性质研究

豆薯（Ｐａｃｈｙｒｒｈｉｚｕｓｅｒｏｓｕｓ）种子经磷酸盐缓冲液抽提,Ｓ－ＳｅｐｈａｒｏｓｅＦａｓｔＦｌｏｗ柱,ＤＥ－５２纤维素柱和ＳｅｐｈａｄｅｘＧ－７５柱层析,提取出两种高纯度的蛋白成分,命名为ＰａｃｈｙｒｉｎＩ和ＩＩ,ＳＤＳ－ＰＡＧＥ测得其分子量分别为３３ｋＤ和１４．５ｋＤ,但ＨＰＬＣ分子筛的结果显示ＰａｃｈｙｒｉｎⅡ的分子量为２８ｋＤ,无论在还原条件下,还是在非还原条件下,ＰａｃｈｙｒｉｎＩ     

尖吻蝮蛇毒内一种新的抗血小板凝集蛋白agkisacuta …

从皖南尖吻蝮蛇毒中经阴离子交换层析和凝胶过滤层析分离纯化离纯化得到抗血小板凝集蛋白ａｇｋｉｓａｃｕｔａｃｉｎ,纯化的ａｇｋｉｓａｃｕｔａｃｉｎ由分子量为１４ｋＤ和１５ｋＤ的２条肽链通过二硫键连接,能有效抑制ｒｉｓｔｏｃｅｔｉｎ诱导的血小板凝集（ＩＣ５０为１８．５ｍｇ／Ｌ）,能轻微抑制凝血酶诱导的血小板聚集（ＩＣ５０为１．２２ｇ／Ｌ）,但对ＡＤＰ、胶原诱导的血小板聚集无影响。ａｇｋｉｓａｃｕｔａｃｉ     

人早期胎盘绒毛纤维连接蛋白的分离纯化及鉴定

人妊娠５－８周的胎盘绒毛经匀浆后,用２ｍｏｌ／Ｌ ｕｒｅａ－ＰＢＳ提取,通过Ｈｅｐａｒｉｎ－Ｓｅｐｈａｒｏｓｅ ４Ｂ亲和柱层析,再经Ｓｅｐｈａｒｏｓｅ ＣＬ－６Ｂ凝胶过滤层析,得到人早期胎盘纤维连接蛋白（ｅａｒｌｙ ｐｌａｃｅｎｔａ ｆｉｂ－ｂｒｏｎｅｃｔｉｎ,ｅｐＦＮ）。经还原及非还原ＳＤＳ－ＰＡＧＥ和免疫印迹电泳分析,ｅｐＦＮ分子量约５００ｋＤ,是由两个２５０ｋＤ亚基组成,与人足月胎盘纤维连接     

Physiochemical characterization of proteolytic cleavage fragments of bovine colostral immunoglobulin G1 (IgG1).

Normal bovine colostral immunoglobulin G1 was subjected to enzymic digestion (pepsin, papain and trypsin) and the resulting fragments separated by a combination of molecularsieve and phosphocellulose chromatography.Fragments F(ab')2 derived from peptic digestion, fragment Fab from papain digestion and fragment Fab(t) from tryptic digestion showed complete antigenic identity with each other. Although fragment F(ab')2 (peptic digestion) had a sedimentation coefficient (S2o,w) of 5.3S, those for fragments Fab' (peptic digestion), Fab (papain digestion) and Fab(t) (tryptic digestion) were found to be 3.9S, 3.7S and 3.7S respectively. The mol.wts. calculated for the various fragments from the sedimentation equilibrium data were: F(ab')2, 104000 +/-200; Fab', 51900+/-340; Fab, 50900+/-230; Fab(t) 50900+/-300. Fragment Fc' (peptic digestion) had an S20,w of 3.2S and a mol. wt. of 42900+/-650; fragment Fc (papain digestion) had an SI0,w of 3.7S and a mol.wt. of 50800+/-300; fragment Fc(t) had an S20,w of 3.7S and a mol.wt. of 50800+/-300; fragment Fc(t) had an S20,w of 3.7S and a mol.wt. of 50800+/-450.     

Purification of recombinant chimeric B72.3 Fab' and F(ab')2 using streptococcal protein G.

Streptococcal protein G has been used extensively for the purification of antibodies using the interaction of the Fc region with protein G. Many antibodies also interact with protein G through a low-affinity binding site for the Fab region. The exploitation of this low-affinity interaction for the purification of Fab' fragments is described here. Chimeric mouse-human B72.3 Fab' and F(ab')2 fragments were expressed by CHO cells and purified from CHO cell supernatant using protein G-Sepharose. Since chimeric B72.3 Fab' bound weakly to the protein G-Sepharose it could be separated from F(ab')2 and eluted with a pH 7 wash whereas B72.3 F(ab')2 required elution at pH 2. Both Fab' and F(ab')2 were recovered with full immunoreactivity and could be further purified using gel-filtration chromatography to greater than 99% purity. This method allows the simple purification of directly expressed Fab' or F(ab')2 fragments from CHO cell supernatant.     

Polyethylene glycol augments thyroid cAMP responses by fragments from protease-digested TSAb or TSBAb-IgG

In the previous reports, we have demonstrated (1) that polyethylene glycol (PEG)(5%) augmented TSAb (thyroid stimulating antibody)-stimulated cAMP responses of porcine thyroid cells, and (2) that fragments from papain-digested TSBAb (thyroid stimulation blocking antibody) could stimulate thyroid cAMP synthesis. Thus, we studied the effect of 5% PEG on cAMP responses stimulated by the protease-digested TSAb- or TSBAb-fragments. Stimulatory effect of 5% PEG on cAMP production by Fab fragment (Mr 50 KDa) and the retarded fraction (Mr 20 KDa) from the gel-filtration on Sephadex G-100 using papain-digested TSAb-IgG unbound to Protein A-Sepharose was observed. Similar stimulatory effect of 5% PEG on the second fraction (Fc with trace amounts of Fab) in the gel-filtration on Sephadex G-100 using papain digested TSAb-IgG bound to Protein A-Sepharose was observed. Stimulatory effect of PEG on the second fraction was derived from Fab fragment. PEG (5%) also showed stimulatory effect on cAMP production by F(ab')2 fragment (Mr 100 KDa) from the gel-filtration on Sephadex G-100 using pepsin-digested TSAb-IgG unbound to Protein A-Sepharose. PEG (5%) augmented cAMP responses by both Fab and the retarded fractions from the gel-filtration using papain-digested TSBAb-IgG unbound to Protein A when these fractions could stimulate cAMP synthesis. In conclusion, PEG (5%) augments cAMP responses stimulated by F(ab')2, Fab and the smaller molecular components (Mr 20 KDa) separated from protease-digested TSAb-IgG. PEG also augments cAMP responses stimulated by Fab and the smaller molecular components with thyroid stimulating activity separated from papain-digested TSBAb-IgG.     

Thioether-bonded constructs of Fab'gamma and Fc gamma modules utilizing differential reduction of interchain disulfide bonds

We describe a two-stage preparation of chemically engineered Ab constructs, employing as modules Fab'gamma from mAb or rAb, and Fc from human normal IgG1. A multivalent, optionally multispecific F(ab')(n) core is formed in stage one, and one or more Fc modules added in stage two. Examples include bispecific Fab(2)Fc(2) (for simplicity, primes and Greek letters are omitted from names of final constructs) and trivalent Fab(3)Fc(2), which are designed to kill neoplastic cells. An essential element in the construction is the availability of the Fab' in two reduced forms, Fab'(-sulfhydryl (SH))(5) and Fab'-SH. The first is obtained by full reduction of the interchain disulfide bonds (SS) in the F(ab')(2) fragment of IgG. Fab'-SH is obtained by disulfide-interchange reactions on Fab'(-SH)(5), whereby the gamma-light SS is reconstituted, an unusual intrachain SS forms in the gamma-chain hinge, and one hinge SH remains. F(ab')(2) and F(ab')(3) cores are built using partially reduced modules, being given intermodular thioether links that resist reduction. These cores are then fully reduced, making available SH groups for addition of the Fcgamma modules. In the final constructs, all intermodular links embody tandem thioether bonds arising at hinge-region cysteines. Cytotoxic activities of representative constructs, and some enhancements deriving from multiple modules, are assessed. In guinea pigs, catabolism of Fab(2)Fc(2) yielded a t(1/2) similar to that of human IgG1, although the serum Fab(2)Fc(2) revealed some proteolytic breakdown not shown by the IgG1. Immunotherapy of a guinea-pig leukemia confirmed the ability of these constructs to kill target cells in vivo.     

The role of A-cells in affecting the immunostimulating effect of F(ab')2-fragments

The immunoregulatory effect of F(ab')2 fragments on normal rabbit IgG and that preincubated with A-cells from spleen have been compared. Both products were tested for their ability to enhance primary immune response of rabbit spleen cells to SRBC. It was demonstrated that low molecular mass product appeared after F(ab')2 fragments incubation with A-cells at 37 degrees C and possessed immunostimulating activity similar to that of initial F(ab')2 fragments. In addition, it was shown that F(ab')2 reduction to monovalent Fab' fragment with the following alkylation of SH-group abolished the ability of Fab' fragment to enhance the immune response. It may signify that half cystein Fab' fragment residue is essential for processing of the fragment in A-cells and (or) for immune response enhancement.     

Glycosylation in the Fc domain of IgG increases resistance to proteolytic cleavage by papain

IgG antibodies (Abs) and fragments of IgG Abs are becoming major biotherapeutics to treat an assortment of human diseases. Commonly prepared fragments of IgGs include Fc, Fab, and F(ab')2 fragments, all of which can be made using the sulfhydryl protease papain, although prolonged digestion times and/or excessive amounts of papain typically result in further cleavage of the Fc domain into smaller fragments. During our attempts to use papain to isolate Fc fragments from different IgG monoclonal Abs, it was observed that prior removal of Fc glycans resulted in a faster rate of papain-mediated degradation of the Fc domain. Subsequent time-course experiments comparing glycosylated and deglycosylated versions of IgG antibodies showed that the majority of molecules in a deglycosylated IgG sample were converted into Fab, Fc, and smaller Fc fragments in less than one hour, whereas the original glycosylated IgG required more than two hours to convert into a comparable amount of Fab and Fc fragments. Furthermore, whereas papain digestion converted almost all of a deglycosylated Fc fragment into smaller fragments of approximately 10 and approximately 12 kDa within 4 h, more than 40% of a glycosylated Fc fragment remained intact even after 24 h of digestion. These results indicate that the presence of CH(2) domain glycans in either IgGs or purified Fc fragments increases resistance to papain digestion. Increased sensitivity of non-glycosylated Fc domains to papain is consistent with the Fc domains lacking a defined structure, as exemplified by their inability to bind Fcgamma receptors, since misfolded proteins are often degraded by proteases because of increased accessibility of their proteolytic cleavage sites. Based on these observations it is possible to use papain sensitivity as a means of assessing proper Fc structure of IgG molecules.     

Radiolocalisation of an anti-CEA monoclonal antibody (FO23C5) and its fragments in a colon carcinoma xenograft model

A new monoclonal antibody designated FO23C5 against a protein component of carcinoembryonic antigen (CEA) has been developed. A xenograft system of human colon cancer was used to compare the intact monoclonal IgG with its fragments (Fab')2 and Fab) and with an established anti-CEA antibody (MAb35) and the antibody AUA1 raised against the colon carcinoma cell line. We demonstrate that FO23C5 compares well with the existing anti-CEA antibody and with AUA1, and that F(ab')2 fragments perform best in achieving optimal tumour to normal tissue ratios compared with intact IgG and Fab fragment.     

Pretargeting for cancer radioimmunotherapy with bispecific antibodies: role of the bispecific antibody's valency for the tumor target antigen

The use of a divalent effector molecule improves bispecific antibody (bsMAb) pretargeting by enabling the cross-linking of monovalently bound bsMAb on the cell surface, thereby increasing the functional affinity of a bsMAb. In this work, it was determined if a bsMAb with divalency for the primary target antigen would improve bsMAb pretargeting of a divalent hapten. The pretargeting of a (99m)Tc-labeled divalent DTPA-peptide, IMP-192, using a bsMAb prepared by chemically coupling two Fab' fragments, one with monovalent specificity to the primary target antigen, carcinoembryonic antigen (CEA), and to indium-loaded DTPA [DTPA(In)], was compared to two other bsMAbs, both with divalency to CEA. One conjugate used the whole anti-CEA IgG, while the other used the anti-CEA F(ab')(2) fragment to make bsMAbs that had divalency to CEA, but with different molecular weights to affect their pharmacokinetic behavior. The rate of bsMAb blood clearance was a function of molecular weight (IgG x Fab' < F(ab')(2) x Fab' < Fab' x Fab' conjugate). The IgG x Fab' bsMAb conjugate had the highest uptake and longest retention in the tumor. However, when used for pretargeting, the F(ab')(2) x Fab' conjugate allowed for superior tumor accretion of the (99m)Tc-IMP-192 peptide, because its more rapid clearance from the blood enabled early intervention with the radiolabeled peptide when tumor uptake of the bsMAb was at its peak. Excellent peptide targeting was also seen with the Fab' x Fab' conjugate, albeit tumor uptake was lower than with the F(ab')(2) x Fab' conjugate. Because the IgG x Fab' bsMAb cleared from the blood so slowly, when the peptide was given at the time of its maximum tumor accretion, the peptide was captured predominantly by the bsMAb in the blood. Several strategies were explored to reduce the IgG x Fab' bsMAb remaining in the blood to take advantage of its 3-4-fold higher tumor accretion than the other bsMAb conjugates. A number of agents were tested, including those that could clear the bsMAb from the blood (e.g., galactosylated or nongalactosylated anti-id antibody) and those that could block the anti-DTPA(In) binding arm [e.g., DTPA(In), divalent-DTPA(In) peptide, and DTPA coupled to bovine serum albumin (BSA) or IgG]. When clearing agents were given 65 h after the IgG x Fab' conjugate (time of maximum tumor accretion for this bsMAb), (99m)Tc-IMP-192 levels in the blood were significantly reduced, but a majority of the peptide localized in the liver. Increasing the interval between the clearing agent and the time the peptide was given to allow for further processing of the bsMAb-clearing agent complex did not improve targeting. At the dose and level of substitution tested, galacosylated BSA-DTPA(In) was cleared too quickly to be an effective blocking agent, but BSA- and IgG-DTPA(In) conjugates were able to reduce the uptake of the (99m)Tc-IMP-192 in the blood and liver. Tumor/nontumor ratios compared favorably for the radiolabeled peptide using the IgG x Fab'/blocking agent combination and the F(ab')(2) x Fab' (no clearing/blocking agent), and peptide uptake 3 h after the blocking agent even exceeded that of the F(ab')(2) x Fab'. However, this higher level of peptide in the tumor was not sustained over 24 h, and actually decreased to levels lower than that seen with the F(ab')(2) x Fab' by this time. These results demonstrate that divalency of a bsMAb to its primary target antigen can lead to higher tumor accretion by a pretargeted divalent peptide, but that the pharmacokinetic behavior of the bsMAb also needs to be optimized to allow for its clearance from the blood. Otherwise, blocking agents will need to be developed to reduce unwanted peptide uptake in normal tissues.     

Purification of antibody Fab and F(ab')2 fragments using Gradiflow technology

The Gradiflow, a preparative electrophoresis instrument designed to separate molecules on the basis of their size and charge, was used to purify antibody Fab and F(ab')2 fragments. The method described is charge based, utilizing the difference in the pI between the antibody Fab/F(ab')2 fragments and antibody Fc fragments that occur after enzyme digestion of whole antibody molecules. This method of purification was successful across a range of monoclonal and polyclonal antibodies. In particular, F(ab')2 fragments were purified from a number of mouse monoclonal antibodies (both IgG1 and IgG2a isotypes) and Fab fragments were purified from egg yolk IgY polyclonal antibodies. This is a rapid purification method which has advantages over alternative methods that usually comprise ion exchange and gel filtration chromatography. This method may be applicable to most antibody digest preparations.     

抗CD20嵌合抗体片段F(ab′)2突变体在大肠杆菌中的高效分泌表达

构建抗CD20嵌合抗体片段F(ab′)₂ 突变体 ,研究其在大肠杆菌中的高效表达及其表达产物的生物学活性。采用PCR法构建抗CD20嵌合抗体片段F(ab′)₂ 突变体 ,并用双脱氧终止法测定DNA序列 ;采用 19L发酵罐高密度发酵抗CD20嵌合抗体片段F(ab′)₂ 突变体 ,采用亲和色谱和分子筛色谱法纯化表达产物 ,并用SDS-PAGE和薄层激光扫描鉴定纯化产物 ;采用活细胞间接免疫荧光法测定纯化产物与靶细胞的结合活性 ;MTT法测定纯化产物对Raji细胞的生长抑制作用 ,并研究其作用机理。DNA序列测定结果表明 ,抗CD20嵌合抗体片段F(ab′)₂ 突变体已成功构建 ,表达可溶性产物的产量达 360mg L ,具有与Raji细胞 (CD20⁺)结合的活性 ,并抑制Raji细胞的生长 ,其作用机理为诱导Raji细胞凋亡。此突变体有望成为治疗非何杰金氏B细胞淋巴瘤的药物。