一组抗人肺癌单克隆抗体的制备及初步鉴定

本文报告用人肺腺癌细胞株A549细胞为免疫原,用常规细胞融合技术获得了5株抗人肺癌单克隆抗体WLA-1B4、WLA-2D1、WLA-1G7、WLA-1G9和WLA-2C4。前4株均为IgM型,后1株为IgG1型。添加试验表明WLA-2D1和WLA-1G9识别同一抗原决定簇,WLA-2C4,WLA-1B4识别不同的抗原决定簇。ABC法免疫组织化学研究表明,5株单抗与肺癌组织均呈阳性反应,而与正常组织交叉反应较少。     

运用表位嵌合型3型腺病毒载体制备肠道病毒71型单克隆抗体

目的制备针对肠道病毒71型(EV71)的单克隆抗体(m Ab)。方法将六邻体中同时嵌入EV71 SP55与SP70两个中和表位的重组人3型腺病毒作为免疫原免疫小鼠,利用杂交瘤技术制备m Ab。用病毒微量中和实验、间接ELISA、Western blot法和直接免疫荧光染色法进行鉴定。结果获得了4株分泌EV71特异性m Ab的杂交瘤细胞,D2C9、2C4、I2G2、I12C3,其中D2C9株腹水间接ELISA实验效价为1∶8 000 000,其余3株为1∶500 000;Western blot法和ELISA结果表明4株m Ab均识别EV71病毒VP1蛋白。D2C9针对SP70表位,2C4、I12C3、I2G2针对SP55表位;直接免疫荧光实验结果显示4株m Ab均能与EV71特异性结合,而与柯萨奇病毒16型(Cox A16)不结合。结论获得了对EV71亲和力高、特异性好并且与Cox A16无交叉反应的m Ab。     

抗艰难梭菌A毒素单克隆抗体的制备及特性分析

目的 :制备抗艰难梭菌A毒素的单克隆抗体 (mAb)并鉴定其特性。方法 :用纯化的艰难梭菌A毒素免疫BALB/c小鼠 ,将免疫小鼠的脾细胞与骨髓瘤细胞Sp2 / 0融合 ,采用间接ELISA筛选杂交瘤细胞。用ELISA检测mAb腹水的效价、相对亲和力和进行表位分析 ;用Westernblot检测mAb的特异性。结果 :得到 6株杂交瘤细胞株 ,5C10株细胞分泌的mAb为IgG2a ,4B5和 8A1株细胞分泌的mAb为IgG1,其他 3株细胞mAb (2H7、3E9和 6G8)均分泌IgM。中和试验表明 ,所有的mAb均无中和活性。腹水mAb的效价均在 10 -4以上 ,其中mAb 2H7、6G8、5C10、4B5和 8A1具有共同的表位 ,而mAb 3E9识别的位点与其他 5株不同。mAb 8A1和 4B5的相对亲和力>10 5,其他 4株mAb的相对亲和力 >10 4。在非变性条件下 ,PAGE后Westernblot的结果显示 ,6株mAb均可与相对分子质量 (Mr)为 5 5× 10 4的A毒素产生反应 ;而在变性条件下 ,还原与非还原SDS PAGE后Westernblot均显示 ,6株mAb均可与Mr 为 5× 10 4～ 2 4× 10 4的A毒素产生反应。结论 :6株杂交瘤细胞株均能分泌抗艰难梭菌A毒素的特异性mAb ,为艰难梭菌A毒素的研究提供了有利的工具     

有机膦半抗原诱导的抗神经性毒剂单克隆抗体的制备及鉴定

目的 :制备新化合物 1 羟基 1 对胺基苯基甲磷酸单频哪基醇酯 (P4 )的单克隆抗体 (mAb)。方法 :以P4为半抗原 ,与血蓝蛋白 (LPH)化学偶联制备人工抗原 (P4 LPH) ,并以其免疫BALB/c小鼠 ,制备抗P4的mAb。用竞争抑制酶免疫分析法 ,测定mAb对梭曼等 7种配体的结合活性 ,结果以mAb与P4 BSA的结合被抑制 5 0 %时的配体浓度 (IC50 ) ,表示mAb的交叉反应性。结果 :建立了 9株对P4 BSA阳性反应的mAb ,它们分属 3种Ig亚类 ;6株 (2B2、3A10、3D5、4F1、6C9和 6H4 )为IgG1,1株 (3B9)为IgG2b ,2株 (1B3和 6H5 )为IgM。 9株mAb中 ,8株具有与半抗原P4的结合的特异性。4株 (1B3、2B2、3D5和 4F1)具有梭曼结合活性 ,其IC50 值分别为 10 -3 、10 -3 、10 -5和 10 -6mol/L ;1株 (4F1)具有与对氧磷结合的特异性 ,其IC50 值为 10 -5mol/L。 4株腹水的mAb鼠滴度高 ,分别达 10 -6(1B3和 2B2 )和 10 -8(3D5和 4F1)。结论 :用新的半抗原P4成功地制得抗梭曼和抗对氧磷的mAb ,可用于梭曼抗体酶、梭曼的免疫抗毒和免疫检测研究     

抗克伦特罗单克隆抗体杂交瘤的建立及其分泌单抗的免疫学特性鉴定

目的 :建立抗克伦特罗 (CL)单克隆抗体杂交瘤细胞系 ,制备CL单克隆抗体 ,并鉴定其免疫学特性。方法 :用重氮化法将半抗原CL偶联于载体蛋白BSA ,形成结合抗原BSA CL ;以BSA CL免疫BALB/C小鼠 ,应用杂交瘤技术建立分泌CL单克隆抗体细胞株 ;用体内诱生腹水法生产CL单抗 ,硫酸钠盐析法提纯。应用抗小鼠同种型抗体测定单抗的同种型 ,用竞争性ELISA和胶体金膜层析试验测定CL单抗的反应特异性和反应动力学。结果 :筛选出C 4G1、C 2H6、C 2D6和C 4C94株高敏感性和高特异性杂交瘤生产单抗 ,其单抗的间接ELISA效价分别为 5× 10 -5、3× 10 -4、6× 10 -4、2× 10 -5;同种型分别为IgG1/κ、IgG1/κ、IgG2a/κ、IgG2a/λ。C 4G1的亲和力常数K =1 6 8× 10 8L/mol,C 2H6的亲和力常数K =1 3× 10 8L/mol。经WestGold蛋白质印迹鉴定单抗与CL特异性结合。C 4G1单抗对CL的半数抑制浓度 (IC50 )为 7 94ng/ml,对沙丁胺醇 (Sb)的IC50 为 10 0 0ng/ml,对肾上腺素、去甲肾上腺素、异丙肾上腺素和来克多巴胺的IC50 均≥ 6 4 0 0ng/ml;C 4G1单抗与Sb的交叉反应性为0 79% ,与异丙肾上腺素的交叉反应性为 0 12 % ,而与肾上腺素、去甲肾上腺素、来克多巴胺、各类抗生素及多种维生素均无交叉反应性。结论 :用单克隆抗体杂交瘤技术     

单克隆抗体亲和层析法提纯人重组IL—2

本文用正辛酸沉淀法提纯了四株抗IL-2单克隆抗体(8H7、982、9812、9F5),并与溴化氢活化的Sepharose4B 偶联制成亲和层折柱纯化人重组IL-2(rhIL-2)。结果表明四根单抗亲和层析柱均可有效地纯化rhIL-2,其中9B12柱和9F5柱的提取率分别达到49.2%和37.5%,提取物纯度在95%以上,并具有较高的生物活性。     

重组人α2a型干扰素单克隆抗体的研制、特性鉴定及初步应用

应用常规方法建立了5株稳定分泌抗重组人α2a 型干扰素单克隆抗体的小鼠杂交瘤细胞系1B8、2B6、3F1、4G5和5G10,并对其免疫学特性进行了较系统的鉴定.5株单抗均为 IgG1,特异性强,与重组人α1 型、γ型干扰素以及受体菌菌体蛋白成分无交叉反应.间接 ELISA 测定小鼠腹水单抗效价1:320,000～1:10,240,000,其中3F1和5G10单抗对重组人α2a 型干扰素具中和活性(中和效价均为1:10,000)。竞争结合 ELISA 证实5株单抗针对3种不同表位。用3F1和5G10单抗建立的夹心 ELISA 能检测到60pg/ml的重组人α2a 和α2b 型干扰素。3F1单抗用于制备亲和层析柱纯化重组人α2a 型干扰素结果与进口单抗NK2相当。     

恙虫病东方体58kDa热休克蛋白与47kDa外膜蛋白的基因嵌合及58-47嵌合基因在大肠杆菌中的表达

采用PCR方法 ,从恙虫病东方体Karp株基因组DNA中扩增 5 8kDa热休克蛋白的基因 ,将该基因分别与原核表达载体pQE30及 4 7kDa外膜蛋白的基因重组质粒 (pQE30 4 7)连接 ,构建pQE30 5 8及pQE30 5 8 4 7重组质粒 ,用重组质粒转化大肠杆菌。SDS PAGE显示 ,pQE30 5 8和pQE30 5 8 4 7转化的大肠杆菌分别产生一 5 8kDa重组蛋白和一 90kDa的双抗原 (5 8- 4 7)融合蛋白。免疫印迹分析显示Karp株免疫血清能特异识别 5 8kDa重组蛋白和 90kDa融合蛋白 ,90kDa融合蛋白既与 4 7kDa重组蛋白也与 5 8kDa重组蛋白的免疫血清特异反应 ,5 8kDa与 4 7kDa重组蛋白也被 90kDa融合蛋白免疫血清所识别。研究结果证明 5 8 4 7融合蛋白具有恙虫病东方体Karp株 4 7kDa外膜蛋白和 5 8kDa热休克蛋白的抗原特性     

草鱼免疫球蛋白单克隆抗体的制备及其特性鉴定

目的:研制抗草鱼免疫球蛋白IgM的单克隆抗体(mAb)并进行免疫学特性分析.方法:制备草鱼免疫球蛋白IgM, 以其为抗原免疫8周龄雌性BALB/c小鼠, 3～4次免疫后取其脾细胞与Sp2/0骨髓瘤细胞融合, 用ELISA法对杂交瘤进行筛选, 并鉴定mAb的生物学特性.结果:各株阳性克隆经3次亚克隆后, 共获得5株抗草鱼IgM的mAbs, 分别命名为4B3、 2B11、 4D5、 3F2和4E6, 它们的细胞上清ELISA效价为1∶ 3 200～1∶ 6 400, 其中4D5的细胞上清及腹水效价分别为1∶ 6 400和1∶ 256 000, 经亚类鉴定结果表明5株mAb均为IgG1.交叉反应结果表明5株mAb均不与台湾甲鱼、泰国甲鱼、日本甲鱼和中华鳖的血清反应, 除mAb 4B3外, 其余4株均与草鱼、青鱼、鲢鱼、鳊鱼和花鱼骨的血清有明显的交叉反应, 而与鲫鱼、鳗鱼的血清只有微弱的反应.mAb 4B3只与草鱼和青鱼的血清有反应, 而与其他鱼类血清反应很弱.免疫印迹实验结果表明mAb 4D5能在变性条件下识别草鱼IgM的重链.ELISA检测mAb 4D5对草鱼IgM的敏感性达10 μg/L.结论:制备的抗草鱼IgM mAb可用于草鱼免疫球蛋白的结构分析、免疫应答水平监测和病原诊断等, 具有广阔的应用前景.     

抗猪流行性腹泻病毒单克隆抗体杂交瘤细胞株的建立及初步应用

用提此的猪流行性腹泻病毒抗原免疫BALB／c小鼠，脾细胞与NS-1骨髓瘤细胞融合，用酶联免疫吸附试验(ELISA)间接法筛选，以有限稀释法克隆化，阳性率选100％，建立了1D8，5D7，4B1，2B3，1A4五株杂交瘸细胞系。用ELISA检测培养上清及诱生的腹水的效价。培养上清效价为1D8 1：1280^x，5D7 1：640^x，4B1 1：320^x 2B8 1：320^x，1A4 1：640^x，腹水效价寿1D8 10^-7，5D7 10^-7、4B1 10^-7，2B8 10^-5，1A4 10^-4。用免疫双扩散试验结果，五株单抗中有一株属IgG类。四株属IgG类。将单抗提此后用ELISA央心间接法及间接免疫荧光试验(IFA)对6神冠状病毒进行了特异性鉴定，除猪流行腹泻病毒外，不与其它冠状病毒发生交叉反应。取效价高而稳定的1D8，5D7，4B1细胞系单克隆抗体做IFA及直接EISA试验初步证明该McAb具有敏感性高，特异性强的优点，可作为猪流行性腹泻病毒检测的一种新试剂。     

IL-3 and IL-4 affect thymocyte differentiation in organ culture.

The ability of lymphokines to affect the development and differentiation of mouse thymocytes in vitro was evaluated in a carefully controlled 3-day organ culture system. Concanavalin A (Con A)-induced supernatant (SN) from the T-cell clone D10.G4, which contains high concentrations of interleukin-3 (IL-3), IL-4 and IL-5, but lacks IL-1, IL-2 and interferon (IFN), markedly increased the proportion of CD4+CD8- cells, and decreased the proportion of CD4+CD8+ cells. These effects were unaffected by dialysing the SN, showing them to be caused by macromolecular factors. Highly purified recombinant IL-3 and IL-4 could exert similar effects, rIL-3 and rIL-4 both increasing the proportion of CD4+CD8- cells, and rIL4 in addition reducing the proportion of CD4+CD8+ cells. In conjunction with the findings of other investigators, these results indicate that at least four lymphokines (IL-1, IL-2, IL-3 and IL-4) can control T-cell development in the thymus.     

Individuals infected with HIV possess antibodies against IL-2.

Studies are presented here which demonstrate that antibodies reacting with human interleukin-2 (IL-2) are present in the sera of patients infected with the human immunodeficiency virus (HIV). It is likely that these antibodies are present due to a homology between the HIV envelope protein and IL-2. The homologues are six amino acids in length corresponding to the carboxy terminus of gp41, Leu-Glu-Arg-Ile-Leu-Leu (LERILL), and residues 14-19 of secreted IL-2, Leu-Glu-His-Leu-Leu-Leu (LEHLLL). Thus, we questioned whether antibodies made against this HIV envelope peptide would cross-react with IL-2. Not only do a high percentage of the HIV-infected individuals tested here have antibodies against LERILL, but these antibodies cross-react with the IL-2 sequence, LEHLLL. Additional antigenic processing of IL-2 is suggested by the finding that epitopes other than this sixmer are also recognized by antibodies in patients' sera. Thus, these studies suggest a mechanism by which infection with HIV can induce a potentially suppressive autoimmune response. Specifically, antibodies against an HIV envelope peptide cross-react with an epitope in IL-2.     

Cytokine-specific ELISPOT assay single cell analysis of IL-2, IL-4 and IL-6 producing cells

In order to assess cytokine-producing cells at the single cell level, the cytokine-specific ELISPOT assay has proven to be an important and sensitive method. The purpose of this study was to adapt this method to elucidate individual cells producing murine IL-2, IL-4 or IL-6. In order to establish these cytokine-specific ELISPOT assays, IL-2-, IL-4- and IL-6-specific cDNA transfected myeloma cell lines, e.g., X63-Ag8-653 X2, X63-Ag8-653 X4 and X63-Ag8-653 X6, respectively, were used as specific cytokine-producing cells. In the IL-2 ELISPOT assay, the coating reagent, monoclonal antibody (mAb) rat IgG2a anti-mouse IL-2 (CR #40014) was used while rabbit IgG polyclonal anti-mouse IL-2 was employed for detection of IL-2 spot forming cells (SFC). The mAbs anti-mouse IL-4, BVD4-1D11 and BVD6-24G2 were selected as capture and detection antibodies for enumeration of IL-4 SFC. For the IL-6 ELISPOT assay, anti-mouse IL-6 (MP5-20F3) mAb was used for coating and MP5-32C11 mAb was used for detection of IL-6 SFC. When IL-2 producing X63-Ag8-653 X2 cells were subjected to these three different ELISPOT assays, IL-2-specific SFC were only noted with the IL-2 ELISPOT system. In the case of IL-4 SFC, only X63-Ag8-653 X4 cells formed specific spots using the tandem of BVD4-1D11 and BVD6-24G2 mAbs. IL-6-specific spots developed in MP5-20F3 mAb pre-coated wells containing X63-Ag8-653 X6 cells, when developed with mAb anti-IL-6 (MP5-32C11). Addition of cycloheximide (50 μg/ml) inhibited formation of IL-2, IL-4 and IL-6 SFC by approximately 90%. When an unrelated mAb was used as detection antibody in these three different cytokine-specific ELISPOT assays, IL-2-, IL-4-and IL-6-specific SFC were not detected. Further, when concanavalin A stimulated T cells from Peyer's patch of normal mice were subjected to the respective cytokine-specific ELISPOT assay, IL-2, IL-4 and IL-6 SFC were enumerated. These results have shown that cytokine-specific IL-2, IL-4 and IL-6 ELISPOT assays have now been established and will allow analysis of the frequency of cytokine-secreting cells at the single cell level.     

Complement C5a anaphylatoxin is an innate determinant of dendritic cell-induced Th1 immunity to Mycobacterium bovis BCG infection in mice

During acquired immunity to Mycobacterium bovis bacillus Calmette-Guerin (BCG) infection in mice, dendritic cells (DCs) present mycobacterial antigens to naive T cells to prime an immune response. Complement C5a (anaphylatoxin) secreted by mycobacteria-infected macrophages regulates IL-12p70 production. As IL-12p70 regulates Th1 immunity against mycobacteria in mice, we examined the effects of C5a on IL-12p70 secretion by murine DCs and Th1 immunity. DCs cultured from C5-deficient (C5(-/-)) and -sufficient (C5(+/+)) mice were infected with BCG in the presence or absence of the C5a peptide. ELISA showed that C5(-/-) DCs secreted less IL-12p70 (600 pg/mL vs. 100 pg/mL) than C5(+/+) DCs, and they secreted more IL-10. Using immunophenotyping, reduced CD40 expression was found on C5(-/-) DCs after BCG infection. BCG-primed DCs were then cocultured with naive or BCG-immune T cells to differentiate them into IFN-gamma-secreting Th1 T cells. Coincident with increased IL-12p70 levels, BCG-primed C5(+/+) DCs cocultured with naive or immune C5(+/+) T cells showed a larger increase in CD4+ IFN-gamma/CD8+ IFN-gamma+ T cells compared with cocultured DCs and T cells from C5(-/-) mice. Thus, BCG-primed C5(+/+) DCs were better able to drive a Th1 response. Furthermore, BCG aerosol-infected C5(-/-) mice showed reduced CD4 and CD8 IFN-gamma-secreting T cells in the lungs, concurrent with an increased growth of BCG. Thus, C5a, an innate peptide, appears to play an important role in the generation of acquired immune responses in mice by regulating the Th1 response through modulation of IL-12p70 secretion from DCs.     

Neutrophil stimulation by recombinant cytokines and a factor produced by IL-1-treated human synovial cell cultures.

Neutrophil accumulation and activation are early events in the inflammatory response in vivo. Using human recombinant forms of the putative inflammatory mediators interleukin-1 (IL-1) and tumour necrosis factor (TNF alpha) we were unable to detect direct effects on human neutrophil locomotion or intracellular free calcium concentration ([Ca2+]i) in vitro. Human recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) was able to stimulate significant locomotion, but was unable to elevate neutrophil [Ca2+]i. In contrast, supernatant from cultured human synovial cells that had been treated with human recombinant IL-1 alpha (28 pM) released a factor that stimulated both neutrophil locomotion and elevated neutrophil [Ca2+]i. Our studies demonstrate that the production of this factor is time-dependent, requiring exposure of the synovial cells to IL-1 for more than 4 hr, is not influenced by cyclo-oxygenase or lipo-oxygenase inhibition, but can be abolished by dexamethasone (100 nM) or actinomycin D (0.8 microM). The factor has a molecular weight above 10,000 and does not cross-react with anti-C5a antisera. IL-1 beta and TNF alpha were also able to stimulate its production. Our findings suggest that the neutrophil accumulation that is known to occur in response to IL-1 in vivo may be a consequence of the local production of such a factor.     

IL-5 production by CD4+ T cells of asthmatic patients is suppressed by glucocorticoids and the immunosuppressants FK506 and cyclosporin A

IL-5 was produced in vitro by peripheral blood mononuclear cells(PBMC) of mite-sensitive atopic patients upon challenge withspecific allergen, while PBMC of healthy controls produced essentiallyno IL-5. Stimuli delivered by the combination of phorbol esterand Ca²⁺ ionophore induced marked IL-5 production by PBMC obtainedfrom atopic and non-atoplc asthmatics, suggesting that bothprotein kinase C and Ca²⁺ Influx are required for IL-5 production.CD2- or CD4-bearlng cell depletion almost completely removedIL-5-produclng cells while CD8-bearing cell depletion ratherenriched them. These findings indicate that CD4⁺ T cells arethe principal source of IL-5 in PBMC. The capacity of PBMC ofatopic asthmatics, non-atopic asthmatics and healthy controlsto produce IL-2, IL-4, IL-5 and IFN- was compared, to find thatcytokine-producing capacities other than that of IL-5 (IL-2,IL-4 and IFN-) were not significantly different among the threegroups. Dexamethasone, FK506 and cyclosporin A suppressed IL-5production in vitro in a dose-dependent manner. Clear dose-dependentsuppression of IL-5 gene expression by FK506 was also observed.Treatment of asthmatic patients with inhaled glucocorticoid(beclomethasone dipropionate) ameliorated clinical symptoms,improved lung function and markedly suppressed IL-5 productionby PBMC, suggesting the essential role of IL-5 in the pathogenesisof bronchial asthma and the clinical importance of its regulation.     

The characterization of testicular cell (TC)-specific T-cell clones induced by intratesticular Listeria monocytogenes infection: TC-specific T cells with atypical cytokine profile transfer orchitis.

A unilateral infection of Listeria monocytogenes into the testis of mice induces not only Listeria-specific T cells but also autoreactive T cells that can transfer experimental autoimmune orchitis (EAO) into naive mice. To investigate the characteristics of the autoreactive T cells, we established six testicular cell (TC)-specific T-cell clones from the spleen of the intratesticularly infected mice. All the clones expressed CD4 and T-cell receptor (TCR) alpha beta, and four of the six clones expressed V beta 8. They showed proliferative response to TC in the presence of syngeneic spleen antigen-presenting cells, but did not cross-react to Listeria antigen (Ag). They produced interferon-gamma (IFN-gamma) when stimulated with TC, but interleukin-2 (IL-2), IL-4 and IL-10 were undetectable. IL-2 production was not detected even when they were restimulated with TC after a 10-day resting culture without Ag and IL-2, although they proliferated in the restimulation culture. Even in the presence of anti-IL-2 mAb, the TC-specific T-cell clones showed proliferative response against TC. The observations indicate that the TC-specific IFN-gamma-producing T cells proliferate in the absence of autocrine. Both intravenous and intratesticular injection of these clones transferred EAO in syngeneic naive mice. These results suggest that L. monocytogenes infection in the testis induces autoreactive orchitogenic CD4+ T cells without cross-reactivity to bacterial Ag. Furthermore, these data demonstrate that CD4+ T cells with an atypical cytokine profile can efficiently cause EAO.     

Complement activation predicts negative outcomes in COVID-19: The experience from Northen Italian patients.

Coronavirus disease 19 (COVID-19) may present as a multi-organ disease with a hyperinflammatory and prothrombotic response (immunothrombosis) in addition to upper and lower airway involvement. Previous data showed that complement activation plays a role in immunothrombosis mainly in severe forms.The study aimed to investigate whether complement involvement is present in the early phases of the disease and can be predictive of a negative outcome.We enrolled 97 symptomatic patients with a positive RT-PCR for SARS-CoV-2 presenting to the emergency room. The patients with mild symptoms/lung involvement at CT-scan were discharged and the remaining were hospitalized. All the patients were evaluated after a 4-week follow-up and classified as mild (n. 54), moderate (n. 17) or severe COVID-19 (n. 26). Blood samples collected before starting any anti-inflammatory/immunosuppressive therapy were assessed for soluble C5b-9 (sC5b-9) and C5a plasma levels by ELISA, and for the following serum mediators by ELLA: IL-1β, IL-6, IL-8, TNFα, IL-4, IL-10, IL-12p70, IFNγ, IFNα, VEGF-A, VEGF-B, GM-CSF, IL-2, IL-17A, VEGFR2, BLyS. Additional routine laboratory parameters were measured (fibrin fragment D-dimer, C-reactive protein, ferritin, white blood cells, neutrophils, lymphocytes, monocytes, platelets, prothrombin time, activated partial thromboplastin time, and fibrinogen). Fifty age and sex-matched healthy controls were also evaluated.SC5b-9 and C5a plasma levels were significantly increased in the hospitalized patients (moderate and severe) in comparison with the non-hospitalized mild group. SC5b9 and C5a plasma levels were predictive of the disease severity evaluated one month later. IL-6, IL-8, TNFα, IL-10 and complement split products were higher in moderate/severe versus non-hospitalized mild COVID-19 patients and healthy controls but with a huge heterogeneity. SC5b-9 and C5a plasma levels correlated positively with CRP, ferritin values and the neutrophil/lymphocyte ratio.Complement can be activated in the very early phases of the disease, even in mild non-hospitalized patients. Complement activation can be observed even when pro-inflammatory cytokines are not increased, and predicts a negative outcome.     

Effects of anti-immunoglobulin antibodies, interleukin-4 and second messenger agonists on B cells from neonatal mice.

Crosslinking of surface Ig receptors on mature B cells with mitogenic anti-Ig antibodies stimulates phosphoinositide breakdown with subsequent activation of protein kinase C (PKC) and elevation of [Ca2+]i leading to B-cell activation. This response can be mimicked using second messenger agonists such as phorbol 12,13-dibutyrate (PDB) plus a Ca2+ ionophore. Furthermore, interleukin-4 (IL-4) synergizes with sub-mitogenic concentrations of anti-Ig (or with PDB) to activate adult B cells. In contrast anti-Ig does not activate neonatal B cells but rather desensitizes or kills them. The nature of the signals involved in these effects on neonatal B cells is poorly understood. Here we have investigated the proliferative responses of small, resting B cells from 1-, 4-, 8-, and 12-week-old mice stimulated with combinations of anti-Ig, PDB, ionomycin and IL-4. We find that B cells from 8- and 12-week-old mice show an adult pattern of reactivity. B cells from 4-week-old mice respond to high doses of anti-Ig, anti-Ig + IL-4 and also to PDB + ionomycin + IL-4, but not to PDB + ionomycin alone. Neonatal (1-week-old) B cells respond only to the combination of PDB, ionomycin and IL-4. Most strikingly, pre-incubation of neonatal cells with anti-Ig completely abrogates this response, whilst IL-4 renders them refractory to such anti-Ig mediated inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)