CD+4CD+25调节性T细胞在小儿急性白血病发病中的作用

目的 观察CD+4 CD+25调节性T(Treg)细胞在急性白血病患儿及非白血病患儿外周血中的变化,研究CD+4 CD+25 Treg细胞在小儿急性白血病发病中的作用.方法 采用流式细胞术检测急性白血病初诊患儿组20例及非白血病患儿对照组20例外周血CD+4 CD+25 Treg细胞的数量及比例.结果 初诊患儿组及对照组外周血CD+4 CD+25 CD-127 Treg细胞占CD+4 T细胞的比例分别为(11.57±1.04)%和(6.75±0.75)%,在初诊患儿组高于对照组(t=16.808,P<0.001).结论 急性白血病患儿外周血中CD+4 CD+25 CD-127 Treg细胞数量升高,提示CD+4 CD+25 Treg细胞可能在白血病的发生、发展中起一定作用.     

小儿急性淋巴细胞白血病血清CD3+ CD4- CD8- T细胞和T细胞亚群的变化及其临床意义

目的 探讨小儿急性淋巴细胞白血病(ALL)外周血CD3+ CD4- CD8- T细胞(DNT细胞)及T淋巴细胞亚群的变化及意义.方法 采用免疫荧光流式细胞术检测30例ALL患儿及24例健康小儿外周血DNT细胞及T淋巴细胞亚群CD3+ T细胞、CD3+ CD4+ T细胞及CD3+ CD8+ T细胞水平.结果 DNT细胞、CD3+ T细胞、CD3+ CD4+ T细胞百分比均明显低于对照组,分别为(4.93±3.75)%比(8.19±3.21)%(t=3.4,P<0.01):(49.99 ±11.70)%比(64.13 ±11.39)%(t=4.1,P<0.01);(28.30 ±7.56)%比(34.61 ±6.43)%(t=3.2,P<0.01);而CD3+ CD8+ T细胞百分比明显高于对照组,为(31.19±9.89)%比(24.33 ±4.24)%(t=3.1,P<0.01).结论 ALL患儿外周血DNT细胞及T亚群的变化提示患儿体内存在免疫功能紊乱,这可能与ALL的发病机制有关.     

CD20在成年人急性B淋巴细胞白血病中的表达及其临床意义

目的 检测CD20在成年人急性B淋巴细胞白血病(B-ALL)的表达,探讨其与临床特点的相关性.方法 回顾性总结分析96例成年B-ALL患者CD20表达情况,结合其临床特性和治疗转归进行分析.结果 96例成年B-ALL患者中,CD20阳性29例(30.20%),CD20阴性67例(69.79%).CD20阳性组与阴性组男女比分别为1.42∶1和1.79∶1(x2=0.27,P＞0.05),中位年龄分别为28岁与23岁,肝脾及淋巴结浸润比例分别为44.83%和41.38%、40.30%和35.82%,髓系抗原表达比例分别为51.72%与56.72%,Ph染色体和bcr-abl融合基因阳性比例分别为24.14%与28.36%,4周内完全缓解率分别为73.08%与68.85%,差异均无统计学意义(P值均＞0.05).在复发率和3年总体生存率上,CD20阳性组分别为54.55%与14.80%,CD20阴性组分别为29.63%与37.30%,两组间差异有统计学意义(x2=0.42,x2=5.31;P值均＜0.05).结论 CD20在成年人B-ALL表达与临床特点无相关性,但对判断患者的预后有一定的指导意义.     

CD133免疫磁珠分选脑肿瘤干细胞及其生物学特性

目的:从人脑肿瘤组织中分离、培养、纯化和鉴定脑肿瘤干细胞(BTSCs),探讨CD133免疫磁珠分选方法获取BTSCs的可行性及BTSCs的生物学特性.方法:留取人脑胶质母细胞瘤新鲜标本,分离获得脑肿瘤细胞.应用CD133免疫磁珠分选方法纯化BTSCs;流式细胞仪检测分选阳性率;神经球计数法分析CD133+/-亚群细胞神经球形成情况;免疫荧光方法检测CD133+/-亚群细胞表面神经干细胞(NSCs)标记物CD133、神经巢蛋白(nestin)表达情况;检测CD133+/-亚群细胞经诱导分化后细胞表面分化标记物β-TubulinⅢ、GFAP表达情况.结果:CD133+亚群细胞具有干细胞特性,可形成明显的神经球,具有自我更新和明显的增殖能力,并且NSCs标记物CD133、nestin表达阳性,经诱导分化后分化标记物β-TubulinⅢ、GFAP表达阳性;CD133-亚群细胞无上述特性.结论:CD133免疫磁珠分选方法获得的CD133+亚群细胞即为BTSCs,该方法可以得到高纯度的BTSCs,可以用于BTSCs的实验研究.     

成年人伴CD2表达B系急性淋巴细胞白血病免疫表型特征分析

目的 了解成年人伴CD2表达B系急性淋巴细胞白血病(CD+2 B-ALL)的免疫表型特征,为临床诊断、治疗及预后判断提供依据.方法 应用流式细胞术及多种单克降抗体检测18例成年人CD+2B-ALL及68例CD-2 B-ALL患者的免疫表型,并对其结果进行分析比较.结果 CD+2 B-ALL的发病年龄明显小于CD-2 B-ALL,18例成年人CD+2 B-ALL的大部分表面标志物与CD-2 B-ALL相似,其中CD10表达水平[(73.78±26.67)%]高于CD-2 B-ALL[(52.84±35.25)%],差异有统计学意义(t=2.35,P<0.05),CD33表达水平[(15.46±27.41)%]则低于CD-2 B-ALL[(31.15±27.72)%],差异有统计学意义(t=2.16,P<0.05);所有B-ALL患者都高表达CD34,阳性表达率分别为72.2%(13/18)和80.9%(55/68),差异无统计学意义(χ2=0.64,P>0.05).CD+2 B-ALL的CD20阳性率明显低于CD-2 B-ALL,差异有统计学意义(χ2=11.38,P<0.05).CD+2 B-ALL伴髓系抗原(CD13或CD33)表达率为44.4%(8/18),明显低于CD-2 B-ALL的72.1%(49/68),差异有统计学意义(χ2=4.86,P<0.05).结论 成年人CD+2 B-ALL与CD-2 B-ALL具有相似的免疫表型,主要来源于造血干细胞的恶性转化,CD+2 B-ALL伴髓系抗原(CD13、CD33)及CD20表达明显低于CD2 B-ALL,提示成年人CD+2 B-ALL可能有较好的预后.     

CD4+T细胞表位预测及其应用

目前,运用生物软件预测CD4+T细胞表位的技术越来越成熟,为表位疫苗的研究提供了有利的条件.对T细胞表位预测技术及其应用进行了综述.     

急性白血病患者造血干细胞P-选择素表达的研究

目的 研究急性白血病(AL)患者骨髓白血病干细胞表面分子P-选择素(CD62P)的表达情况及其临床意义.方法 采用流式细胞术(FCM)检测56例初治AL患者骨髓CD62P的表达情况,以15例健康成年人骨髓标本为对照.结果 38例急性髓系白血病(AML)患者干细胞(CD+45CD+34CD-38)中CD62P平均表达水平为(6.72±7.64)%,12例急性B淋巴细胞白血病(B-ALL)患者干细胞(CD+45CD+34CD+19)为(3.46±2.51)%,6例急性T淋巴细胞白血病(T-ALL)患者干细胞(CD+45 CD+34CD+7)为(6.23±4.95)%,均明显高于健康对照组[(1.04±1.23)%](t值分别为2.847、3.284、3.091,P＜0.01).经过正规方案治疗后,完全缓解组患者CD62P表达与健康对照差异无统计学意义(t=0.397,P＞0.05).另外CD+62P的AML及T-ALL患者白细胞计数、血红蛋白及血小板计数均明显高于CD-62P患者(t值分别为4.153、8.095、8.289、7.235、8.692、9.832,P＜0.05);而CD+62P与CD-62P的B-ALL患者无明显差异(t值分别为0.340、1.142、0.019,P＞0.05).结论 CD62P是血小板活化的标志物之一,在不同类型的AL中有不同程度的表达.AL骨髓造血干细胞中CD62P可能作为白血病造血干细胞的标志,以及临床疗效观察预后判断的指标之一.     

细胞黏附分子SLeX和CD24在喉鳞状细胞癌组织中的表达

目的:探讨细胞黏附分子唾液酸化Lewis-X抗原(SLeX)和CD24在喉鳞状细胞癌组织中的表达,阐明其在喉鳞状细胞癌发生发展中的作用.方法:采用免疫组织化学方法分别检测42例喉鳞状细胞癌患者的42个原发灶、24个相应癌旁组织及20例睡眠呼吸暂停低通气综合征(OSAHS)手术患者的咽部正常黏膜组织中SLeX和CD24的表达情况.结果:喉癌组织、癌旁组织及对照正常黏膜组织中SLeX阳性表达率分别为71.4%、37.5%和30.0%;强阳性表达率分别为50.0%、8.3%和5.0%.CD24的阳性表达率分别为64.3%、33.3%和25.0%;强阳性表达率分别为35.7%、4.2%和0.0%.3组间两两比较,喉癌组织与癌旁组织、正常黏膜组织阳性表达率差异均有统计学意义(P<0.01);癌旁组织与正常黏膜组织阳性表达率差异无统计学意义(P>0.05).SLeX、CD24强阳性表达与颈部淋巴结转移情况、临床分期及组织病理学分级相关(P<0.05).SleX和CD24在喉癌组织中的阳性率呈显著正相关关系(r=0.695,P<0.05).结论:SLeX及CD24蛋白表达与喉鳞状细胞癌的发生发展密切相关,其检测对喉癌的生物治疗和预测预后具有一定的临床意义.     

多发性骨髓瘤患者基质细胞衍生因子-1α、CD44v6表达的研究

目的 探讨基质细胞衍生因子-1α(SDF-1α)、CD44v6(一种变异的CD44受体)在多发性骨髓瘤(MM)中的表达水平及其与病情进展的关系.方法 用酶联免疫吸附试验(ELISA)检测24例MM患者[14例初发和复发MM患者(初发和复发MM组),10例病情稳定MM患者(病情稳定MM组)]和15位健康骨髓移植供者或非肿瘤良性贫血患者(对照组)的骨髓单个核细胞(MNC)和骨髓基质细胞(BMSC)培养上清的SDF-1 α、CD44v6水平.结果 初发和复发MM组MNC培养上清的SDF-1α、CD44v6表达水平[(7232.41±2644.97)pg/ml和(34.34±13.20)ng/ml]显著高于病情稳定MM组[(2315.49±748.29)pg/ml和(15.69±5.28)ng/m1](t=6.25、t=7.82;均P＜0.05)和对照组[(1149.52±636.06)pg/ml和(4.85±3.62)ng/ml](t=4.60、t=7.61;均P＜0.05).病情稳定MM组SDF-1α、CD44v6水平显著高于对照绀(t=2.99、t=4.87;均P＜0.05).9例初发和复发MM组的BMSC与人类骨髓瘤细胞系细胞U266加入rhIL-6进行混合培养后,SDF-1 α水平[(6180.25±5925.38)pg/ml]显著高于5例对照组BMSC[(1021.13±358.65)pg/ml]和9例初发和复发MM组[(1004.07±727.36)pg/ml](t=2.66、t=2.42;均P＜0.05).而其他BMSC各组问的SDF-1α水平差异无统计学意义(P＞0.05).SDF-1 α与CD44v6两者表达水平呈正相关(r=0.51,P=0.03).结论 SDF-1 α、CD44v6水平升高与MM的病情进展或发病有关,也可能与MM的肿瘤浸润过程有关;而这些体内过程可能需骨髓瘤细胞和BMSC与IL-6、SDF-1α和CD44v6等因素协同完成.     

应激性高血糖对急性心肌梗死的影响

目的:应激性高血糖增加急性心肌梗死(AMI)患者的死亡率,因此我们研究首发急性心肌梗死患者血浆葡萄糖水平、循环炎症介质、T细胞活化和心脏功能恶化之间的关系.方法:对105例急症住院的急性心肌梗死患者的心电图、血白介素18(IL-18),C反应蛋白(CPR),CD16-CD56,CD4/CD8,CD152的百分比和HLA-DR表达进行研究.结果:研究发现31例应急性高血糖急性心肌梗死患者与36例糖尿病急性心肌梗死患者和41例血糖正常的急性心肌梗死患者比较(血糖≥7mmol/1)心肌梗死段长度(p<0.05)心脏指数(p<0.02),多普勒血流分布减少(p<0.05)、肺动脉血流分析(p<0.02),射血分数(p<0.05).应急性血糖高的心肌梗死患者的IL-18、CPR比血糖正常患者的高(p<0.005),其中应急性高血糖患者的值最高(p<0.05),应急性高血糖患者与血糖正常患者比CD16+/CD56+及CD4/CD8细胞百分比高,而CD152表达少(活化T细胞有一个负调节功能)(p<0 001).结论:急性心肌梗死期间的高血糖与炎症介质的增加有关,促进细胞毒性T细胞的表达,减少T细胞表达,限制了免疫过程,急性心肌梗死增加的免疫炎症过程可能是应急性高血糖使心肌功能恶化的机制之一.     

Interferons alpha/beta inhibit IL-7-induced proliferation of CD4- CD8- CD3- CD44+ CD25+ thymocytes, but do not inhibit that of CD4- CD8- CD3- CD44- CD25- thymocytes

We have determined partial sequences of the gyrA and parC genes of Enterobacter cloacae type strain including the regions analogous to the quinolone resistance-determining region of the Escherichia coli gyrA gene. The deduced 65- and 49-amino acid sequences of the determined regions of the E. cloacae gyrA and parC genes were identical to the corresponding regions of the E. coli GyrA and ParC proteins, respectively. We examined 40 clinical strains of E. cloacae isolated from patients with urinary tract infection for susceptibilities to nalidixic acid and ciprofloxacin. Based on the nalidixic acid and ciprofloxacin MICs, these isolates were divided into 19 quinolone-susceptible strains (MICs of nalidixic acid, 3.13-25 mg/L; MICs of ciprofloxacin, < or = 0.025 mg/L) and 21 quinolone-resistant strains (MICs of nalidixic acid, 400 to > 800 mg/L; MICs of ciprofloxacin, 0.39-100 mg/L). We analysed five quinolone-susceptible and 21 quinolone-resistant strains for alterations in GyrA and ParC. The five quinolone-susceptible strains had amino acid sequences in GyrA and ParC identical to those of type strain. Of the 21 quinolone-resistant isolates, three (MICs of nalidixic acid, 400 to > 800 mg/L; MICs of ciprofloxacin, 0.39-3.13 mg/L) had a single amino acid change at the position equivalent to Ser-83 in the E. coli GyrA protein and no alterations in ParC; one (MIC of nalidixic acid, > 800 mg/L; MIC of ciprofloxacin, 3.13 mg/L) had a single amino acid change at Ser-83 in GyrA and a single amino acid change at the position equivalent to Glu-84 in the E. coli ParC protein; two (MIC of nalidixic acid, > 800 mg/L; MIC of ciprofloxacin, 25 mg/L) had double amino acid changes at Ser-83 and Asp-87 in GyrA and no alterations in ParC; and 15 (MICs of nalidixic acid, > 800 mg/L; MICs of ciprofloxacin, 25-100 mg/L) had double amino acid changes at Ser-83 and Asp-87 in GyrA and a single amino acid change at Ser-80 or Glu-84 in ParC. This study suggests, that in clinical isolates of E. cloacae, DNA gyrase is a primary target of quinolones, that only a single amino acid change at Ser-83 in GyrA is sufficient to generate high-level resistance to nalidixic acid and to decrease susceptibility to ciprofloxacin, and that the accumulation of amino acid changes in GyrA and the simultaneous presence of the ParC alterations play a central role in developing high-level resistance to ciprofloxacin.     

CD19 is linked to the integrin-associated tetraspans CD9, CD81, and CD82

The CD19-CD21-CD81 complex regulates signal transduction events critical for B lymphocyte development and humoral immunity. CD81, a molecule with 4 transmembrane domains, member of the tetraspan superfamily, is engaged, together with other tetraspans such as CD9, CD53, CD63, and CD82, in multimolecular complexes containing beta1 integrins and major histocompatibility complex antigens. Here we demonstrate that two other tetraspans, CD82 and the early B cell marker CD9, are coimmunoprecipitated with CD19 from Brij97 lysates of B cell lines. Moreover, CD9 was coprecipitated from lysates of purified CD10(+) early B cells. These associations were confirmed by the cocapping of CD19 with CD9 or CD82. The CD9/CD19 association was disrupted in the presence of digitonin, contrary to the CD81/CD19 association, indicating that CD9 and CD81 interact with CD19 in different ways. The CD9/CD81 association is also disrupted in the presence of digitonin, suggesting that CD9 associates with CD19 only through CD81. To characterize the regions involved in the CD81/CD19 association, two reciprocal CD9/CD81 chimeric molecules were tested for the association with CD19, but none of them could be coprecipitated with CD19 in digitonin, indicating that the domain of CD81 responsible for its association with CD19 is complex. Finally, engagement of CD9 could induce the tyrosine phosphorylation of different proteins, including CD19 itself, suggesting that the CD9/CD19 association is functionally relevant. Thus, a physical and functional link is formed between the CD19-CD21-CD81 complex and the integrin-tetraspan complexes, which is dynamically modulated in the process of B cell differentiation.     

Cellular characteristics of acute leukemia cells simultaneously expressing CD13/CD33, CD7 and CD19

Of 832 acute leukemia patients, including 580 acute myeloblastic leukemia (AML), 197 pre-B acute lymphoblastic leukemia (ALL) and 55 pre-T ALL, 26 cases (3.1%) of CD13/CD33+CD7+CD19+ acute leukemia were found. A total of 20 patients were diagnosed as AML, two as pre-B ALL and four as pre-T ALL. Based on the relative intensity of expression of CD7 and CD19, CD13/CD33+CD7+CD19+ acute leukemia patients were subclassified into three categories. Type I (CD7 > CD19) included ten AML and four pre-T ALL, having cellular characteristics similar to CD7+ AML and CD13/CD33+CD7+ ALL. Type II (CD7 < CD19) consisted of four AML with t(8;21) and two pre-B ALL. Type III (CD7 = CD19) included six AML. CD13/CD33+CD7+CD19+ acute leukemia frequently expressed stem cell associated molecules, such as CD34 (88.5%), HLA-DR (96.2%) and mRNA for MDR1 (72.2%), GATA-2 (87.5%) and SCL (25.0%). Simultaneous expression of cytoplasmic CD3 and myeloperoxidase in some leukemia cells implies that CD13/CD33+CD7+CD19+ acute leukemia cells have the potential to differentiate into various lineages. These data suggest that a small population of acute leukemia patients with distinct phenotype, CD13/CD33+CD7+CD19+ acute leukemia, may originate from hematopoietic stem cells.     

CD11/CD18 and CD14 share a common lipid A signaling pathway

The activation of phagocytes by the lipid A moiety of LPS has been implicated in the pathogenesis of Gram-negative sepsis. While two LPS receptors, CD14 and CD11/CD18, have been associated with cell signaling, details of the LPS signal transduction cascade remain obscure. CD14, which exists as a GPI-anchored and a soluble protein, lacks cytoplasmic-signaling domains, suggesting that an ancillary molecule is required to activate cells. The CD11/CD18 integrins are transmembrane proteins. Like CD14, they are capable of mediating LPS-induced cellular activation when expressed on the surface of hamster fibroblasts Chinese hamster ovary (CHO)-K1. The observation that a cytoplasmic deletion mutant is still capable of activating transfected CHO-K1 argues that CD11/CD18 also utilizes an associated signal transducer. We sought to identify further similarities between the signaling systems utilized by CD14 and CD11/CD18. LPS-binding protein, which transfers LPS to CD14, enhanced both LPS-induced cellular activation and binding of Gram-negative bacteria in CD11/CD18-transfected CHO-K1, thus implying that LPS-binding protein can also transfer LPS to CD11/CD18. When synthetic lipid A analogues were analyzed for their ability to function as LPS agonists, or antagonists, in the CHO transfectants, we found the effects were identical regardless of which LPS receptor was expressed. This supports the hypothesis that a receptor distinct from CD14 and CD11/CD18 is responsible for discriminating between the lipid A of LPS and the LPS antagonists. We propose that this receptor, which is the target of the LPS antagonists, functions as the true signal transducer in LPS-induced cellular activation for both CD14 and CD11/CD18.     

Differential CD26-mediated activation of the CD3 and CD2 pathways after CD6-depleted allogeneic bone marrow transplantation

Patients who have undergone allogeneic bone marrow transplantation (allo-BMT) are susceptible to a variety of opportunistic infectious complications in the months to years after engraftment. Impaired in vitro T-cell functions have been documented in these patients, and these T-cell dysfunctions contribute to the prolonged immune deficiency after allo-BMT. In the present study, we examined the expression of CD26 as well as the reconstitution of CD26-mediated T-cell costimulation via the CD3 and CD2 pathways at various times in patients aged greater than 18 years after CD6-positive, T-cell depleted allo-BMT. We found that the percentage of CD26- and CD3-positive cells, as well as the levels of expression of both antigens, was lower than in normal controls during the first 4 months after CD6-depleted allo-BMT. Subsequently, the amount of lymphocytes expressing CD3 and CD26 and the quantitative surface expression of CD3 and CD26 were not significantly different in patients and normal controls. Functional studies showed that CD26-mediated T-cell proliferation via the CD3 pathway was considerably improved and almost reached normal levels by 1 year, whereas recovery of CD26-mediated T-cell proliferation via the CD2 pathway was delayed for at least 2 years after CD6-depleted allo-BMT. As CD26 involvement in the regulation of human thymocyte activation is restricted preferentially to the CD3 pathway--unlike its involvement with both CD3 and CD2 pathways of peripheral T cells--our results suggest that the different effects of CD26-mediated costimulation via the CD3 and CD2 pathways after CD6-depleted allo-BMT may be a reflection of peripheral T-cell immaturity in those individuals, similar to that seen in mature medullary thymocytes or cord T lymphocytes.     

Expression of tetra-spans transmembrane family (CD9, CD37, CD53, CD63, CD81 and CD82) in normal and neoplastic human keratinocytes: an association of CD9 with alpha 3 beta 1 integrin

Tetra-spans transmembrane family (TSTF) members (CD9, CD37, CD53, CD63, CD81 and CD82) have potent effects on cell growth, motility and adhesion in various cells. However, little is known about their expression in human skin. Using immunohistological techniques, we have studied the localization of all six members of TSTF in normal and carcinomatous human keratinocytes. CD9, CD81 and CD82 were expressed in the entire living layers of the epidermis. Their staining pattern was quite similar, and was mainly intercellular with occasional intracellular immunoreactivity. CD53 expression was confined to the intercellular spaces of the upper spinous or granular layer in the normal epidermis. No clear-cut expression of CD63 could be detected in the epidermis. CD37 was not detected at all. Cultured human keratinocytes also expressed CD9, CD81 and CD82 at the surface membrane of cell-cell boundaries. Expression of CD37 and CD53 was negative in cultured keratinocytes, while CD63 was clearly localized in the cytoplasmic lysosomes. An immunoprecipitation assay revealed that alpha 3 beta 1 integrin is molecularly associated with CD9. The expression of CD9, CD81 and CD82 was markedly down-regulated in basal cell carcinoma but not in Bowen's disease. The abundant and differential expression of TSTF molecules and the selective association of CD9 with alpha 3 beta 1 integrin suggest that the TSTF molecules may be involved in the regulation of epidermal differentiation and integrity in vivo.     

Chicken CD4, CD8alphabeta, and CD8alphaalpha T cell co-receptor molecules

New knowledge has recently been obtained about the evolutionary conservation of CD4, CD8alphaalpha, and CD8alphabeta T cell receptor (TCR) co-receptor molecules between chicken and mammals. This conservation extends from biochemical structure and tissue distribution to function. Panels of monoclonal antibodies and polyclonal antisera against different epitopes of chicken CD8 and CD4 molecules have proven their value in several recent studies. Chicken CD8 allotypes and homozygous strains carrying these allotypes have been established and these strains provide excellent models for further studies. The extensive polymorphism of CD8alpha in chickens has not been observed in any other species, suggesting that CD8alpha and CD8beta have evolved under different selective pressure in the chicken. A large peripheral blood CD4+CD8+ T cell population in chicken resembles that observed in some human individuals but the inheritance of peripheral blood CD4CD8alphaalpha T cells in the chicken is a unique observation, which suggests the presence of a single gene responsible for CD8alpha, but not CD8beta, specific expression. Despite these unique findings in chicken, the data on CD4, CD8alphaalpha, and CD8alphabeta molecules show that they have evolved before the divergence of mammalian and avian branches from their reptilian ancestors.     

Definition of the specificity of monoclonal antibodies against porcine CD45 and CD45R: report from the CD45/CD45R and CD44 subgroup of the Second International Swine CD Workshop

Swine cell binding analyses of a set of 48 monoclonal antibodies (mAbs), including eleven standards, assigned to the CD44 and CD45 subset group of the Second International Swine CD Workshop yielded 13 clusters. Although none of these corresponded to CD44, seven mAbs formed a cluster which was identified as being specific for restricted epitopes of CD45 (CD45R). In addition, a T-cell subset specific cluster comprised of four mAbs was also identified. Two mAbs (STH106 and SwNL 554.1) reacted exclusively with CD8 bright lymphocytes, the other two (2B11 and F01G9) with a subset of CD4 lymphocytes. The other 10 clusters were either specific for MHC-class I like molecules or overlapped with clusters identified by the adhesion molecule subgroup and are therefore just briefly discussed in this report. The specificity of all the mAbs in the CD45R cluster was verified by their ability to immunoprecipitate distinct proteins and to react with CHO cells expressing individual isoforms of CD45. Three CD45R mAbs (3a56, MIL5, -a2) did react with a 210 kDa isoform(s), while another three (STH267, FG2F9, 6E3/7) only recognized a 226 kDa isoform(s). The remaining one (MAC326) precipitated both a 210 and 226 kDa protein. The specificity of all the mAbs in the CD45R cluster, and of the CD45 common mAbs, was confirmed by their reactivity with CHO cells transfected with cDNAs encoding the extracellular and transmembrane portions of distinct CD45R isoforms. Those mAbs recognizing a 210 kDa protein reacted with CHO cells expressing the CD45RC isoform, while those capable of precipitating a 226 kDa, but not the 210 kDa, polypeptide recognized CHO cells expressing either the CD45RAC and the relatively rare CD45RA isoform. MAC326 was unique in its inability to react with CHO cells engineered to produce the CD45RC and CD45RAC isoforms. Thus, three mAbs (6E3/7, STH267, and FG2F9) appear to be specific for an epitope(s) encoded by the A exon, while one (MAC326) recognizes a determinant encoded by the C exon. The remaining three mAbs (3a56, -a2, MIL5) are apparently specific for an epitope(s) which results from the fusion of the C exon to the invariant leader sequence and is destroyed by inclusion of the A exon. All three CD45 common mAbs, K252.1E4, MAC323 and 74.9.3, did react with the CHO cells lines expressing either the CD45RA, CD45RC, CD45RAC or CD45RO isoforms, but not with untransfected CHO cells. When the natural expression of CD45 isoforms was examined by reacting lymphocytes with CD45R mAbs, a high level expression of isoforms containing the A exon-generated domain was detected in all B cells while the majority of CD4+ T cells had undetectable or lower expression density of this protein than B cells. In contrast, the density of expression of the CD45 isoform(s) containing the C exon-generated domain ranged from undetectable to high in CD4+ T cells whereas the amounts were approximately ten-fold lower in B cells. Overall this panel of CD45 mAbs will be very useful in analyzing the maturation and differentiation of swine lymphoid cells subsets.