K562 human leukaemic cells express fetal type (i) antigen on different glycoproteins from circulating erythrocytes

During the ontogenic change from fetal to adult human erythrocytes, as well as fetal haemoglobin being replaced by adult haemoglobin, the cell-surface antigen i is converted to I (ref. 1). Recently it has been shown that this antigenic change is the conversion of the linear repeating Gal beta 1 leads to 4GlcNac beta 1 leads to 3Gal structure to branched Gal beta 1 leads to 4GlcNac beta 1 leads to 3(Gal beta 1 leads to 4GlcNac beta 1 leads to 6)Gal structure. We have shown that cell-surface labelling followed by endo-beta-galactosidase digestion can distinguish these two forms on the cell surface, and that band 3 and band 4.5 are the major carriers for these antigens on mature erythrocytes. Human leukaemic cell line K562, originally isolated from a patient at blast crisis of chronic myelocytic leukaemia, has recently been shown to synthesize glycophorin A, and to be capable of synthesizing haemoglobin upon induction. I demonstrate here that K562 cells express the fetal type (i) antigen on distinctly different glycoproteins from those of erythrocytes, by the use of cell-surface labelling followed by endo-beta-galactosidase digestion or followed by immunoprecipitation with specific antibodies.     

IgM-autoantibodies against isologous erythrocytes also react with isologous IgG(Fc)

The mechanisms by which the adaptive immune system of animals discriminate between foreign and self components are not known. It is generally believed that antibodies are produced only in response to foreign agents. However, against this axiom there is mounting evidence that normal animals produce autoantibodies against a variety of self components. In two murine model systems, a high proportion of IgM-producing cells secrete autoantibodies. In one model, the autoantibodies are specific for isologous mouse IgG(Fc) and in the other, the autoantibodies are specific for antigens revealed on the surface of mouse erythrocytes (RBC) by proteolytic enzymes. The function of these two autoimmune responses is a mystery. Here we show that the two responses are related. The lysis of mouse RBC, modified with bromelain (brom) by IgM autoantibodies was completely inhibited by isologous IgG(Fc), and antibodies against mouse IgG(Fc) formed precipitin bands with solubilized membranes from mouse RBC. We conclude that mouse RBC membranes and IgG(Fc) have at least one antigenic determinant in common and that this determinant is the target for autoimmune responses in normal mice.     

两种不同示踪剂用于蛋白质与抗原分子微阵列信号检测的对比研究

以氧化型琼脂糖凝胶膜为基片，制作蛋白质与抗原分子微阵列，建立了检测固相人IgG,游离IgG和自身抗体分子的免疫学测定模式，分别以辣根过氧化物酶－二氨基联苯胺一双氧水（HRPDAB－H2O2）和胶体金－硝酸银－对苯二酚2种示踪系统作为蛋白质与抗原分子微阵列信号显示剂，并对其作用的原理与特点进行讨论，检测结果发现基于胶体金的免疫金银染色法（IGSS）比固相酶免疫测定法（EIA）敏感，2种示踪系统对固相人IgG的最低检出量分别为0．05ng和0．5ng；而对血清游离IgG的最低检出量IGSS法比EIA法至少高出10倍，两法用于自身抗体的测定亦表现出较好的重复性，在14例HCV感染者中，自身抗体的总体检出率分别为38．6％和31．4％，结果具有显著的同步性，故同时辅以2种示踪剂并用于阵列芯片的联合测试，有助于提高自身抗体的总体检出水平。     

The T lymphocyte glycoprotein CD2 binds the cell surface ligand LFA-3

CD2 (known also as T11 (ref. 1), LFA-2 (ref. 2) and the erythrocyte rosette receptor (ref. 3] is a functionally important T lymphocyte surface glycoprotein of relative molecular mass 50,000 to 58,000 (Mr 50-58 K) which appears early in thymocyte ontogeny and is present on all mature T cells. Monoclonal antibodies to CD2 inhibit cytotoxic T-lymphocyte (CTL)-mediated killing by binding to the T lymphocyte and blocking adhesion to the target cell. Such antibodies also inhibit T helper cell responses including antigen-stimulated proliferation, interleukin-2 (IL-2) secretion, and IL-2 receptor expression. Certain combinations of monoclonal antibodies to CD2 epitopes trigger proliferation of peripheral blood T lymphocytes, cytotoxic effector function and expression of IL-2 receptors by thymocytes, resulting in thymocyte proliferation in the presence of exogenous IL-2 (ref. 11). These findings suggest that CD2 can function in signalling as well as being an adhesion molecule. To understand the role of CD2 in T-cell adhesion and activation, it is essential to define its natural ligand. Our previous observation that purified CD2 inhibits rosetting of T lymphocytes with sheep erythrocytes and can be absorbed by sheep erythrocytes suggested it also might bind with detectable affinity to human cells. We now report that CD2 binds to a cell-surface antigen known as lymphocyte function-associated antigen-3 (LFA-3) with high affinity, and can mediate adhesion of lymphoid cells via interaction with LFA-3.     

HCV感染与多种自身抗体高检出率的关系

为探讨丙型肝炎病毒（ＨＣＶ）感染后体内出现的自身抗体的病理意义及其引起的自身免疫的发生机制。方法：对１６１例ＨＣＶ感染者进行了八种自身抗体（抗核抗体、类风湿因子、抗甲状腺球蛋白抗体、抗甲状腺微粒体抗体、抗双链ＤＮＡ抗体、抗ＲＮＰ抗体、抗Ｓｍ抗体、抗精子抗体）的检测。结果：有５２例检出６９项次自身抗体,自身抗体检出率为３２．３％,显著高于健康人对照组（Ｐ＜０．００５）（未计抗精子抗体）。结论：ＨＣＶ感染可能是诱发自身免疫反应的一个重要因素     

An anti-idiotype vaccine against experimental schistosomiasis

Schistosomiasis is a parasitic infection of man which is widespread in tropical countries, and which so far has resisted attempts at control. We have been approaching the problem from an immunological angle. We have previously reported the production of a rat monoclonal IgG2a antibody against Schistosoma mansoni which exhibits marked cytoxicity for schistosomula in the presence of eosinophils and a high degree of protection by passive transfer in naive rats. This antibody, IPLSm1, was shown to bind specifically to a schistosomulum membrane target antigen defined as a glycoprotein of relative molecular mass 38,000 (38K), which is strongly immunogenic in schistosome infection of various animal species including man. Although theoretically the 38K protein represents an excellent candidate for a potential vaccine against schistosomiasis, the glycanic nature of the epitope recognized by IPLSm1 limits its production by DNA recombinant technology. It was, moreover, shown that, together with protective antibodies, the 38K molecule was able to induce the production of blocking IgG2c antibodies that inhibit the functional properties of IPLSm1 both in vitro and in vivo. Therefore, following Jerne's network theory, we considered an alternative approach, the possibility of immunization using anti-idiotype antibodies. In the present study, rat monoclonal anti-idiotype antibodies were produced against IPLSm1 (AB1). Anti-idiotype antibodies (AB2) were selected by their capacity to inhibit the binding of radioiodinated AB1 to its 38K target antigen. Sera from naive LOU rats immunized with a purified AB2 preparation contained specific anti-schistosome antibodies (AB3) which bound to 38K. AB3 antibodies were strongly cytotoxic for schistosomula in the presence of rat eosinophils and conferred highly significant protection by passive transfer. Most importantly, rats immunized with AB2 demonstrated marked protection (50-80%) to a challenge infection.     

The role of clonal selection and somatic mutation in autoimmunity

Polyclonal activation has been proposed as the reason that autoantibodies are produced during autoimmune disease. This model denies a role for specific antigen selection of B cells and predicts instead a multiclonal population of unmutated or randomly mutated autoantibodies. We have found that the genetic features and clonal composition of spontaneously derived immunoglobulin G (IgG) antiself-IgG (rheumatoid factor (RF] autoantibodies derived from the autoimmune MRL/lpr mouse strain are inconsistent with both the predictions of this model and the actual outcome of experimental polyclonal activation. Instead we have found that MRL/lpr RFs are oligoclonal or even monoclonal in origin. They harbour numerous somatic mutations which are distributed in a way that suggests immunoglobulin-receptor-dependent selection of these mutations. In this sense, the MRL/lpr RFs resemble antibodies elicited by exogenous antigens after secondary immunization. The parallels suggest that, like secondary immune responses, antigen stimulation is important in the generation of MRL/lpr RFs.     

痰和咽拭子PCR及血清学联合检测肺炎衣原体急性呼吸道感染

了解成人呼吸道感染患者急性肺炎衣原体感染的发病情况。呼吸道感染患者１１０例,同时采集痰和咽拭子标本,应用聚合酶链式反应（ＰＣＲ）检测肺炎衣原体ＤＮＡ及采静脉血检测肺炎衣原体抗体。本组患者１７例（１６％）有肺炎衣原体近期感染的急性抗体,１２例（１１％）痰和（或）咽拭子肺炎衣原体ＰＣＲ检测阳性,联合应用两种方法的阳性率为２３％（２５／１１０例）。肺炎衣原体急性感染以哮喘急性发作、肺炎、ＣＯＰＤ急性加重和急性支气管炎患者多见（分别为５７％、３５％、２６％和２５％）,其临床表现无特征性。本组成人呼吸道感染患者肺炎衣原体急性感染的发病率较高,提示肺炎衣原体是呼吸道感染的重要致病原。     

Chromatin-IgG complexes activate B cells by dual engagement of IgM and Toll-like receptors

Autoreactive B cells are present in the lymphoid tissues of healthy individuals, but typically remain quiescent. When this homeostasis is perturbed, the formation of self-reactive antibodies can have serious pathological consequences. B cells expressing an antigen receptor specific for self-immunoglobulin-gamma (IgG) make a class of autoantibodies known as rheumatoid factor (RF). Here we show that effective activation of RF+ B cells is mediated by IgG2a-chromatin immune complexes and requires the synergistic engagement of the antigen receptor and a member of the MyD88-dependent Toll-like receptor (TLR) family. Inhibitor studies implicate TLR9. These data establish a critical link between the innate and adaptive immune systems in the development of systemic autoimmune disease and explain the preponderance of autoantibodies reactive with nucleic acid-protein particles. The unique features of this dual-engagement pathway should facilitate the development of therapies that specifically target autoreactive B cells.     

Evidence for a physical association of CD4 and the CD3:alpha:beta T-cell receptor

CD4 is a molecule expressed on the surface of T lymphocytes which recognize foreign protein antigens in the context of class II major histocompatibility complex (MHC) molecules. Recognition of antigen:class II MHC complexes by CD4+ T cells can be inhibited by anti-CD4 (ref. 3). Nevertheless, specific recognition of the antigen:Ia complex is clearly a function of the T-cell receptor, which is composed of CD3 and the variable polypeptides alpha and beta. Thus, it has been proposed that CD4 serves an accessory function in the interaction of CD4+ T cells and Ia-bearing antigen-presenting cells by binding to non-polymorphic portions of class II MHC molecules and stabilizing the cell interaction. Based on our observation that anti-CD4 could inhibit activation of a cloned line of CD4+ T cells by antibodies directed at a particular epitope on the variable region of the T-cell receptor, we have recently proposed that CD4 is actually part of the T-cell antigen recognition complex, physically associated with CD3:alpha:beta. But numerous studies showing that CD3 and CD4 are not stably associated on the T-cell surface would appear to contradict this model. Here we show that anti-T-cell-receptor antibodies can co-modulate expression of the T-cell receptor and CD4, and that the monovalent Fab fragment of such an anti-T-cell-receptor antibody can, in conjunction with bivalent anti-CD4 antibody, generate an activating signal for the T cell. These findings provide further evidence for a physical association of the T-cell receptor complex and CD4.     

Domain interactions of H-2 class I antigens alter cytotoxic T-cell recognition sites

H-2 class I antigens appear to direct the recognition of virus-infected and neoplastic transformed cells by cytotoxic T lymphocytes (CTLs). Here, to identify the regions of class I antigens involved in CTL recognition, four hybrid class I genes were constructed in which exons were exchanged between the H-2Kb and H-2Db genes. These class I genes were expressed in mouse L cells and recognition of the hybrid Kb/Db antigens by CTLs and monoclonal antibodies specific for either Kb or Db was investigated. The pattern of CTL and monoclonal antibody recognition obtained indicates three correlations between structure and function of class I antigens. First, most CTL recognition sites and alloantigenic determinants are located on domains 1 and 2 of the antigen molecule. Second, these CTL recognition sites and alloantigenic determinants are not influenced by interaction of domains 1 and 2 with polymorphic regions of domain 3. Third, in contrast, interaction between domains 1 and 2 alters these CTL recognition sites and alloantigenic determinants. The alteration of CTL recognition sites by interaction between domains 1 and 2 suggests that a CTL site may be formed by amino acids from both domains 1 and 2, or that the conformation of amino acids at a CTL site may be altered by interactions between domains 1 and 2. Through these two features, the conformation of CTL recognition sites on H-2 class I antigens may be sensitive to alteration by interaction of either domain 1 or 2 with viral antigens.     

Immunization to a syngeneic sarcoma by a monoclonal auto-anti-idiotypic antibody

Idiotypic networks regulate the immune response to a variety of antigens. Antibodies generated against other antibodies, called anti-idiotypic antibodies, can themselves mimic antigen and elicit a specific immune response. They have been shown to induce delayed-type hypersensitivity (DTH) to model antigens in the mouse. As anti-idiotypic antibodies are thought to be involved in the response to tumour-associated antigens we tested whether injection of monoclonal antibodies derived from mice hyperimmunized to a syngeneic, chemically induced sarcoma could mimic antigen and induce DTH to the sarcoma in naive mice. One of the monoclonal antibodies, 4.72, primed BALB/c mice for DTH to the sarcoma but not for DTH to another sarcoma or to sheep erythrocytes. Antibody 4.72 did not induce DTH in mice of immunoglobulin allotype congeneic strains nor did it bind to the sarcoma cells. As antibodies specific for this sarcoma have not been detected, we do not know whether idiotype on immunoglobulin molecules is recognized by antibody 4.72. However, as the response induced by antibody 4.72 was both antigen-specific and allotype-restricted, analogous to those induced by anti-idiotypic antibodies in other systems, we propose that antibody 4.72 is an anti-idiotypic antibody.     

Identification of Tim4 as a phosphatidylserine receptor

In programmed cell death, a large number of cells undergo apoptosis, and are engulfed by macrophages to avoid the release of noxious materials from the dying cells. In definitive erythropoiesis, nuclei are expelled from erythroid precursor cells and are engulfed by macrophages. Phosphatidylserine is exposed on the surface of apoptotic cells and on the nuclei expelled from erythroid precursor cells; it works as an 'eat me' signal for phagocytes. Phosphatidylserine is also expressed on the surface of exosomes involved in intercellular signalling. Here we established a library of hamster monoclonal antibodies against mouse peritoneal macrophages, and found an antibody that strongly inhibited the phosphatidylserine-dependent engulfment of apoptotic cells. The antigen recognized by the antibody was identified by expression cloning as a type I transmembrane protein called Tim4 (T-cell immunoglobulin- and mucin-domain-containing molecule; also known as Timd4). Tim4 was expressed in Mac1+ cells in various mouse tissues, including spleen, lymph nodes and fetal liver. Tim4 bound apoptotic cells by recognizing phosphatidylserine via its immunoglobulin domain. The expression of Tim4 in fibroblasts enhanced their ability to engulf apoptotic cells. When the anti-Tim4 monoclonal antibody was administered into mice, the engulfment of apoptotic cells by thymic macrophages was significantly blocked, and the mice developed autoantibodies. Among the other Tim family members, Tim1, but neither Tim2 nor Tim3, specifically bound phosphatidylserine. Tim1- or Tim4-expressing Ba/F3 B cells were bound by exosomes via phosphatidylserine, and exosomes stimulated the interaction between Tim1 and Tim4. These results indicate that Tim4 and Tim1 are phosphatidylserine receptors for the engulfment of apoptotic cells, and may also be involved in intercellular signalling in which exosomes are involved.     

Activated CD8 binding to class I protein mediated by the T-cell receptor results in signalling

The CD8 glycoprotein of T cells bind nonpolymorphic regions of class I major histocompatibility complex proteins on target cells and these interactions promote antigen recognition and signalling by the T-cell receptor. Studies using artificial membranes indicated that effective CD8/class I interaction is critical for response by alloantigen-specific cytotoxic T lymphocytes when class I protein is the only ligand on the antigen-bearing surface. But significant CD8-mediated binding of cytotoxic T lymphocytes to non-antigenic class I protein could not be detected in the absence of the alloantigen. These apparently contradictory findings indicate that CD8 binding to class I protein might be activated through the T-cell receptor and the results reported here demonstrate that this is the case. Treatment of cytotoxic T lymphocytes with soluble anti-T-cell receptor antibody activates adhesion of the cytotoxic T lymphocytes to class I, but not class II proteins. The specificity of this binding implies that it is mediated by CD8 and blocking by anti-CD8 antibodies confirmed this. Furthermore, binding of CD8 to class I protein resulted in generation of an additional signal(s) necessary to initiate response at low T-cell receptor occupancy levels.     

Specific targeting of cytotoxic T cells by anti-T3 linked to anti-target cell antibody

The specificity of cytotoxic T lymphocytes (Tc) cells is conferred by an antigen-specific receptor, Ti, which in humans is physically associated with an invariant cell-surface glycoprotein, T3. Monoclonal antibodies specific for either T3 and Ti are able to elicit a variety of T-cell responses such as lymphokine production, mitogenesis and cytotoxicity. For example, human Tc cells lyse anti-T3-expressing hybridoma cells, but not cells of other specificity, presumably because anti-T3 on the hybridoma cells binds to T3 on the Tc cells and triggers lysis. Here, we have adapted approaches used in a different cytotoxic effector system, antibody-dependent cellular cytotoxicity (ADCC), to alter the specificity of Tc cell. Studies of ADCC showed that heteroaggregates containing anti-Fc receptor (Fc gamma R) antibody cross-linked to a second antibody bind to Fc gamma R on ADCC effectors and cause them to kill target cells bearing antigen recognized by the second antibody. The present studies use anti-T3-containing heteroaggregates to re-target human Tc cells to cells for which we have appropriate antibodies, including xenogeneic tumour cells and chicken erythrocytes. These results extend previous observations on the role of T3 in triggering cytotoxicity and suggest that effector cell re-targeting could be used for in vivo treatment of neoplasms and other pathogens that express distinctive surface antigens.     

红细胞表面电荷的研究 Ⅲ.红细胞年龄对电泳率的影响

本文采用Murphy法分离老、中、青不同年龄的红细胞.经细胞电泳测定,人红细胞电泳率随细胞年龄增大而下降(P<0.01).并进一步证实,人红细胞在体内衰老过程中,其电泳率的下降和唾液酸含量减少有关.     

红细胞表面电荷的研究——III.红细胞年龄对电泳率的影响

本文采用Murphy法分离老、中、青不同年龄的红细胞。经细胞电泳测定,人红细胞电泳率随细胞年龄增大而下降(P<0.01)。并进一步证实,人红细胞在体内衰老过程中,其电泳率的下降和唾液酸含量减少有关。     

Monoclonal antibody production by receptor-mediated electrically induced cell fusion

Fusion of myeloma cells and B lymphocytes to form hybridomas which produce monoclonal antibodies has been a major advance, but the poor efficiency and randomness of viral or polyethylene glycol fusion techniques generally gives poor yields of specific, high affinity antibodies. High voltage electrical fields with dielectrophoresis to ensure cell alignment can fuse a limited number of cells under direct microscopic examination, but it is not possible to identify B-cells destined to secrete relevant antibodies. However, B-cells express, on their surface, antigen receptor immunoglobulins of the same antigenic specificity as the secreted antibodies. Binding of antigen to surface immunoglobulins stimulates proliferation and differentiation of B-cells into plasma cells. Here we report the use of the selective, high affinity interaction of antigen with surface immunoglobulins on B-cells to facilitate a close adherence to myeloma cells. The antigen, covalently conjugated to avidin, binds to the surface immunoglobulins on B-cells. This B-cell-antigen-avidin complex binds to biotin covalently attached to the surface of myeloma cells. An intense electric field across a bulk cell suspension then produces selective fusion of cells in contact, that is, of myeloma cells with B-cells which make the appropriate antibody. We have used this technique with several antigens, and all resultant hybridomas secrete appropriate antibodies with very high affinity.     

小儿肺炎支原体感染52例临床分析

目的探讨小儿肺炎支原体感染的诊断与治疗.方法收集大同市第三人民医院儿科2006年6月-2007年12月小儿肺炎支原体感染52例的临床资料进行分析.52例均做血、尿、大便常规,血清MP-IGM检测及胸部X线照片检查;予以红霉素15mg-30mg（/kg·d）,静脉滴注,每日1次,连用14-21d,或用阿奇霉素10mg/（kg·d）,每日1次,连用7-10d;症状控制后使用阿奇霉素口服序贯疗法,即阿奇霉素10mg（/kg·d）口服,每日1次,连用3d,停药4d,疗程14-21d.结果小儿肺炎支原体感染的发病年龄、季节不恒定,52例中出入院符合小儿肺炎支原体感染诊断者30例,符合率为58%;治愈51例.结论对于疑似患者及使用青霉素类或头孢类抗生素无效者,及时行肺炎支原体感染检查;红霉素、阿奇霉素疗效好.     

Recognition of pre-processed endogenous antigen by class I but not class II MHC-restricted T cells

Class I and class II MHC-restricted T lymphocytes recognize non-native forms of antigen. The presentation of antigen to these two classes of T lymphocytes can occur through distinct pathways. Several mechanisms, including differences in antigen processing in different intracellular compartments, have been proposed to account for these pathway differences. Here we describe a T-cell epitope located on the influenza virus haemaglutinin, which is recognized by both class I and class II MHC-restricted cytolytic T lymphocytes (CTL). When expressed de novo in target cells, from a synthetic minigene encoding only the epitope, this pre-processed antigenic site is recognized by class I but not class II MHC-restricted T lymphocytes, even though target cells treated with the exogenously introduced peptide can be recognized by both classes of T cells. Because endogenous expression of the pre-processed antigenic fragment results in differential presentation to class I and class II MHC-restricted CTL, differences between the two different pathways of presentation could lie not at the level of processing but at the level of targeting and/or interaction of processed antigen with MHC.