文献

PA007200.r2b: Syd Labs体内实验级重组抗小鼠CD4单克隆抗体（克隆号GK1.5），大鼠IgG2b Kappa（In vivo Grade Recombinant Anti-mouse CD4 Monoclonal Antibody (Clone: GK1.5), Rat IgG2b Kappa）

CD4是一种分子量约为 55 kDa 的单链跨膜糖蛋白，主要表达于辅助性T细胞（Th 细胞）表面，同时也表达于部分树突状细胞（DC）及单核/巨噬细胞表面。在免疫应答中，CD4分子作为 T 细胞受体（TCR）的辅受体（Co-receptor），通过特异性结合主要组织相容性复合物 II 类（MHC-II）分子，在 T 细胞激活、信号转导以及适应性免疫应答的维持中发挥核心作用。

在小鼠体内免疫学研究中，GK1.5 克隆（Rat IgG2b, kappa）是目前国际上使用最为广泛的小鼠 CD4+ T 细胞体内清除（In Vivo CD4+ T Cell Depletion）经典工具克隆。GK1.5 抗体能够特异性识别小鼠 CD4 分子，并通过抗体依赖性细胞毒性（ADCC）及抗体依赖性细胞吞噬作用（ADCP）等机制，高选择性地耗竭小鼠体内的 CD4+ T 细胞。这一工具在肿瘤免疫（如评估 CD4+ T 细胞在免疫检查点阻断治疗中的作用）、自身免疫性疾病模型、同种/异种器官移植排斥反应、感染性疾病机制研究以及疫苗研发等领域中具有极其重要的应用价值。

抗小鼠CD4抗体(GK1.5)部分参考文献:

1. Skin autonomous antibody production regulates host–microbiota interactions
Inta Gribonika,et al.Nature. 2025.PMCID: PMC11864984
“The microbiota colonizes each barrier site and broadly controls host physiology1. However, when uncontrolled, microbial colonists can also promote inflammation and induce systemic infection2. The unique strategies used at each barrier tissue to control the coexistence of the host with its microbiota remain largely elusive. Here we uncover that, in the skin, host–microbiota symbiosis depends on the ability of the skin to act as an autonomous lymphoid organ. Notably, an encounter with a new skin commensal promotes two parallel responses, both under the control of Langerhans cells. On one hand, skin commensals induce the formation of classical germinal centres in the lymph node associated with immunoglobulin G1 (IgG1) and IgG3 antibody responses. On the other hand, microbial colonization also leads to the development of tertiary lymphoid organs in the skin that can locally sustain IgG2b and IgG2c responses. These phenomena are supported by the ability of regulatory T cells to convert into T follicular helper cells. Skin autonomous production of antibodies is sufficient to control local microbial biomass, as well as subsequent systemic infection with the same microorganism. Collectively, these results reveal a compartmentalization of humoral responses to the microbiota allowing for control of both microbial symbiosis and potential pathogenesis.”
2. MHC-II presentation by oral Langerhans cells impacts intraepithelial Tc17 abundance and Candida albicans oral infection via CD4 T cells
Peter D. Bittner-Eddy,et al.Front Oral Health. 2024.PMCID: PMC11169704
“In a murine model (LCΔMHC-II) designed to abolish MHC-II expression in Langerhans cells (LCs), ∼18% of oral LCs retain MHC-II, yet oral mucosal CD4 T cells numbers are unaffected. In LCΔMHC-II mice, we now show that oral intraepithelial conventional CD8αβ T cell numbers expand 30-fold. Antibody-mediated ablation of CD4 T cells in wild-type mice also resulted in CD8αβ T cell expansion in the oral mucosa. Therefore, we hypothesize that MHC class II molecules uniquely expressed on Langerhans cells mediate the suppression of intraepithelial resident-memory CD8 T cell numbers via a CD4 T cell-dependent mechanism. The expanded oral CD8 T cells co-expressed CD69 and CD103 and the majority produced IL-17A [CD8 T cytotoxic (Tc)17 cells] with a minority expressing IFN-γ (Tc1 cells). These oral CD8 T cells showed broad T cell receptor Vβ gene usage indicating responsiveness to diverse oral antigens. Generally supporting Tc17 cells, transforming growth factor-β1 (TGF-β1) increased 4-fold in the oral mucosa. Surprisingly, blocking TGF-β1 signaling with the TGF-R1 kinase inhibitor, LY364947, did not reduce Tc17 or Tc1 numbers. Nonetheless, LY364947 increased γδ T cell numbers and decreased CD49a expression on Tc1 cells. Although IL-17A-expressing γδ T cells were reduced by 30%, LCΔMHC-II mice displayed greater resistance to Candida albicans in early stages of oral infection. These findings suggest that modulating MHC-II expression in oral LC may be an effective strategy against fungal infections at mucosal surfaces counteracted by IL-17A-dependent mechanisms.”
3. Complement C3 and marginal zone B cells promote IgG-mediated enhancement of RBC alloimmunization in mice
Arijita Jash,et al.J Clin Invest. 2024.PMCID: PMC11014669
“Administration of anti-RhD immunoglobulin (Ig) to decrease maternal alloimmunization (antibody-mediated immune suppression [AMIS]) was a landmark clinical development. However, IgG has potent immune-stimulatory effects in other settings (antibody-mediated immune enhancement [AMIE]). The dominant thinking has been that IgG causes AMIS for antigens on RBCs but AMIE for soluble antigens. However, we have recently reported that IgG against RBC antigens can cause either AMIS or AMIE as a function of an IgG subclass. Recent advances in mechanistic understanding have demonstrated that RBC alloimmunization requires the IFN-α/-β receptor (IFNAR) and is inhibited by the complement C3 protein. Here, we demonstrate the opposite for AMIE of an RBC alloantigen (IFNAR is not required and C3 enhances). RBC clearance, C3 deposition, and antigen modulation all preceded AMIE, and both CD4+ T cells and marginal zone B cells were required. We detected no significant increase in antigen-specific germinal center B cells, consistent with other studies of RBC alloimmunization that show extrafollicular-like responses. To the best of our knowledge, these findings provide the first evidence of an RBC alloimmunization pathway which is IFNAR independent and C3 dependent, thus further advancing our understanding of RBCs as an immunogen and AMIE as a phenomenon.”

了解更多抗小鼠CD4抗体(克隆号GK1.5)参考文献，请查看：参考文献

问：在 C57BL/6 或 BALB/c 等小鼠模型中，进行 CD4+ T 细胞体内清除（In Vivo Depletion）的标准给药剂量和频次是多少？

答：体内清除 CD4+ T 细胞的推荐给药剂量通常为每只小鼠 100 μg 至 250 μg（约 5 – 10 mg/kg）。常见的体内耗竭给药方案为：在实验起始前（即肿瘤接种、免疫干预或移植前 1–2 天）进行首次腹腔注射（i.p.），随后的维持给药频次为每周 2 次，每次 100–250 μg/只，持续整个实验周期。若需验证耗竭效率，建议在首次给药后 48–72 小时采集外周血或脾脏单细胞悬液进行流式细胞术检测。

问：在给药后评估小鼠外周血或脾脏中 CD4+ T 细胞的清除效率时，流式细胞术（FACS）染色检测有什么关键注意事项？

答：由于体内注射的 GK1.5 抗体会长时间占据小鼠 CD4 分子的结合表位（Epitope Masking），因此在后续使用流式细胞术评估清除效率时，绝对不能使用荧光标记的 GK1.5 克隆抗体进行染色。建议选用与 GK1.5 无表位竞争的抗小鼠 CD4 流式检测克隆（如 RM4-5 或 RM4-4 克隆），或者采用 CD3+ CD8- 细胞群体作为替代门控策略，以避免因表位掩盖导致的流式检测假阴性或结果误读。

问：该重组抗体（PA007200.r2b）用于体内注射时，内毒素（Endotoxin）指标要求如何？

答：体内实验级（In Vivo Grade）重组抗体的内毒素控制极为严苛。该产品的内毒素水平严格控制在低于 1.0 EU/mg（根据高标准批次要求可达到低于 0.1 EU/mg 级）。低内毒素保障了抗体注入小鼠体内后不会引发非特异性的全身炎性响应、细胞因子风暴或非特异性免疫细胞激活，从而确保了实验干预因子的单因素准确性。

问：在设计体内 CD4+ T 细胞耗竭实验时，阴性对照（Isotype Control）应该如何选择？

答：为确保实验设计的严格性，阴性对照组应选用相同亚型及工程化形式的重组大鼠 IgG2b 同型对照抗体（Recombinant Rat IgG2b Isotype Control），且注射剂量、给药途径及频次必须与 GK1.5 实验组完全一致。这可以有效排除大鼠 IgG2b 骨架本身在小鼠体内可能引起的非特异性免疫反应或 Fc 受体结合效应。

问：重组表达的 GK1.5（PA007200.r2b）与传统杂交瘤腹水或杂交瘤培养上清纯化的 GK1.5 有什么核心区别？

答：重组表达抗体采用已确证的基因序列在哺乳动物表达系统（如 HEK293 或 CHO 细胞）中进行体外重组表达与 Protein A/G 亲和纯化。与传统杂交瘤来源抗体相比，重组抗体具备批次间高度一致性（避免了杂交瘤细胞基因漂移或丢失引起的活性波动）、无内源性大鼠免疫球蛋白污染、无宿主病毒及支原体污染，且能够实现极其严格的低内毒素质量控制。

问：产品的缓冲液成分以及正确的储存与复溶方法是什么？

答：该抗体溶解于无菌 PBS 缓冲液（pH 7.2–7.4）中，不含任何载体蛋白（如 BSA）及有害防腐剂（如叠氮化钠 NaN₃），可直接用于小鼠体内注射。收到产品后，短期使用可置于 4°C 避光保存（建议 1–2 周内使用完毕）；如需长期保存，请按单次实验用量无菌分装后置于 -20°C 或 -80°C 避光冻存，严禁反复冻融，以防止抗体发生聚集、沉淀及结合活性下降。

与抗小鼠CD4抗体(克隆号GK1.5) 相关同型对照抗体:

重组大鼠IgG2b同型对照抗体

Syd Labs提供以下体内实验级重组抗人CD4单克隆抗体：

Clenoliximab biosimilar, research grade, anti-human CD4 monoclonal antibody
Ibalizumab biosimilar, research grade, anti-human CD4 monoclonal antibody
Recombinant Anti-human CD4 monoclonal antibody (Clone: OKT4)
Recombinant Anti-human CD4 monoclonal antibody (Clone: OKT4A)
Recombinant Anti-human CD4 monoclonal antibody (Clone: 13B8.2)
Recombinant Anti-human CD4 monoclonal antibody (Clone: SK3 / Anti-LEU 3a)

Syd Labs提供以下体内实验级重组抗小鼠CD4单克隆抗体：

Recombinant Anti-mouse CD4 monoclonal antibody (Clone: GK1.5)

Syd Labs提供以下重组抗人CD4单克隆抗体（流式细胞术用）：

Recombinant Anti-human CD4 monoclonal antibody (Clone: OKT4) for flow cytometry
Recombinant Anti-human CD4 monoclonal antibody (Clone: OKT4A) for flow cytometry
Recombinant Anti-human CD4 monoclonal antibody (Clone: 13B8.2) for flow cytometry
Recombinant Anti-human CD4 monoclonal antibody (Clone: SK3 / Anti-LEU 3a) for flow cytometry