Larkin James M G, Norsworthy Peter J, A'Hern Roger P, Eisen Tim G, Gore Martin E, Porter Colin D
Institute of Cancer Research, Chester Beatty Laboratories bRheumatology Section, Imperial College London, UK.
Melanoma Res. 2006 Apr;16(2):157-63. doi: 10.1097/01.cmr.0000200490.62723.b0.
Antibodies to the cell surface disaccharide galactose(alpha1,3)galactose (alphaGal) are the most prevalent natural antibodies in human serum. The anti-alphaGal immunoglobulin M-dependent activation of complement causes hyperacute rejection of organ transplants from discordant species by human recipients. It has been shown in vitro that human tumour cells transduced with the gene that synthesizes alphaGal become sensitive to human serum. A prerequisite for anti-alphaGal antibody-based therapeutic strategies is that patients with cancer have adequate serum levels of anti-alphaGal immunoglobulins and complement. The objective of this work was to measure the levels and function of anti-alphaGal immunoglobulins and complement in the serum of patients with metastatic melanoma and healthy volunteers. Serum complement levels were assayed by radial immunodiffusion. Anti-alphaGal immunoglobulin G and immunoglobulin M titres were measured by enzyme-linked immunosorbent assay. Disaccharide sugar blocking was used to investigate antibody specificity. The functional integrity of anti-alphaGal antibodies and complement was investigated in cell lysis assays. It was found that the levels of the complement components C1q, C3 and C4 and the function of the classical complement pathway were normal in metastatic melanoma patients. Anti-alphaGal antibody titres were as variable in metastatic melanoma patients as in healthy controls, and the lysis of alphaGal-expressing cells correlated with anti-alphaGal immunoglobulin M titre (P < 0.0001). Anti-alphaGal antibody titres, complement levels and overall cytolytic function in the serum of patients with metastatic melanoma were indistinguishable from those of healthy controls. There is thus nothing intrinsic to the disease that will limit anti-alphaGal-based therapeutic strategies for enhanced antigen presentation or induced cell lysis, including the mimicry of hyperacute rejection.
针对细胞表面二糖半乳糖（α1,3）半乳糖（αGal）的抗体是人类血清中最普遍的天然抗体。抗αGal免疫球蛋白M依赖性补体激活会导致人类受者对不匹配物种的器官移植产生超急性排斥反应。体外实验表明，用合成αGal的基因转导的人类肿瘤细胞对人类血清变得敏感。基于抗αGal抗体的治疗策略的一个前提是癌症患者血清中具有足够水平的抗αGal免疫球蛋白和补体。这项工作的目的是测量转移性黑色素瘤患者和健康志愿者血清中抗αGal免疫球蛋白和补体的水平及功能。血清补体水平通过放射免疫扩散法测定。抗αGal免疫球蛋白G和免疫球蛋白M滴度通过酶联免疫吸附测定法测量。使用二糖阻断来研究抗体特异性。在细胞裂解试验中研究抗αGal抗体和补体的功能完整性。结果发现，转移性黑色素瘤患者补体成分C1q、C3和C4的水平以及经典补体途径的功能正常。转移性黑色素瘤患者的抗αGal抗体滴度与健康对照者一样存在差异，并且表达αGal的细胞的裂解与抗αGal免疫球蛋白M滴度相关（P < 0.0001）。转移性黑色素瘤患者血清中的抗αGal抗体滴度、补体水平和总体细胞溶解功能与健康对照者无异。因此，该疾病本身不存在任何会限制基于抗αGal的增强抗原呈递或诱导细胞裂解的治疗策略的因素，包括模拟超急性排斥反应。
