New strategies to establish human monoclonal antibodies

Cephalin as an efficient fusogen in hybridoma technology: can it replace poly ethylene glycol?

In this study we set up a simple, fast, and highly efficient protocol to fuse cells and produce human hybridoma using non-toxic cephalin as a fusogenic lipid. We compared our proposed method with PEG-mediated fusion, the well-known conventional method. Human lymphoblastoid cells were fused with an F3B6 heteromyeloma cell line using cephalin or PEG as the fusogenic compound. The viability of the cells and their fusion rate were determined microscopically and hybridoma (antigen-specific and non-specific) production yield was calculated following HAT selection and screening. The fusion rates of cells in cephalin and PEG-mediated methods were comparable (25.9+/-5.73% versus 27.3+/-6.07%) while the viability of the cells immediately and after overnight incubation was obviously greater in the cephalin method than in the PEG (p<0.001). Our proposed cephalin-mediated cell fusion method is about five times more efficient than PEG in production of hybridoma clones; thus it may dismiss PEG as the most generalized fusogen in the future.

A new and efficient method to generate human IgG monoclonal antibodies reactive to cancer cells using SCID-hu mice

Human monoclonal antibodies (mAbs) are very useful for treatment of cancer, but they are difficult to obtain since immunization of humans is not a practical proposition at present. As an approach to circumvent this problem, we have simultaneously inoculated cancer tissues and regional lymph node cells obtained from lung cancer patients into SCID mice to allow in vivo stimulation of human lymphocytes against autologous cancer tissues. Human immunoglobulins, especially IgG, were observed in the SCID-hu sera, and some showed high reactivity to lung cancer cell lines. Testing of human B-lymphoblastoid cell lines obtained from SCID-hu spleen and thymus for antibody activity revealed 16-45% of them to be reactive to lung cancer cells. These percentages are high as compared with previous reports. Furthermore, we could establish 4 human IgG mAbs reactive to lung cancer cell lines. These results indicate successful stimulation of specific human lymphocytes in vivo, which thereby enables efficient generation of human monoclonal antibodies using SCID-hu mice.