Tsang H, Pinkert C, Hagman J, Lostrum M, Brinster R L, Storb U
Department of Molecular Genetics and Cell Biology, University of Chicago, IL 60637.
J Immunol. 1988 Jul 1;141(1):308-14.
A complete, functional gamma 2b gene (pVCM) was cloned from a mouse hybridoma (VD93) with antibody activity to Pseudomonas aeruginosa. DNA sequencing of the VDJ region of pVCM determined that the VH gene was a member of the J558 family rearranged to JH2. Upon transfection into myeloma cells the gamma 2b gene gave rise to high levels of gamma 2b mRNA and gamma 2b protein. The gamma 2b protein had the same IEF pattern as the parent hybridoma protein VD93 and the antibodies formed from a combination of the pVCM gamma 2b chains and the myeloma lambda-chains bound weakly to P. aeruginosa. However, the hybrid antibodies did not discriminate between the serotypes 2 and 3, whereas the parent protein was specific for serotype 3. Transgenic mice were produced with the pVCM gamma 2b gene which expressed the gamma 2b mRNA (both membrane and secreted forms) only in lymphoid organs. However, contrary to expectations, the gamma 2b mRNA levels were higher in T cells than in B cells in three different transgenic lines. The serum of the transgenic mice had no activity to P. aeruginosa indicating the importance of L chains for the conformation of the Ag binding site. These gamma 2b transgenic mice provide a convenient tool for the study of feedback inhibition of Ig gene rearrangement.
从一株对铜绿假单胞菌具有抗体活性的小鼠杂交瘤（VD93）中克隆出一个完整的、有功能的γ2b基因（pVCM）。对pVCM的VDJ区域进行DNA测序确定，VH基因是重排至JH2的J558家族成员。将γ2b基因转染至骨髓瘤细胞后，可产生高水平的γ2b mRNA和γ2b蛋白。γ2b蛋白的IEF图谱与亲本杂交瘤蛋白VD93相同，由pVCMγ2b链和骨髓瘤λ链组合形成的抗体与铜绿假单胞菌的结合较弱。然而，杂交抗体不能区分2型和3型血清型，而亲本蛋白对3型血清型具有特异性。用pVCMγ2b基因制备了转基因小鼠，该基因仅在淋巴器官中表达γ2b mRNA（膜型和分泌型）。然而，与预期相反，在三个不同的转基因品系中，γ2b mRNA水平在T细胞中高于B细胞。转基因小鼠的血清对铜绿假单胞菌无活性，表明轻链对Ag结合位点构象的重要性。这些γ2b转基因小鼠为研究Ig基因重排的反馈抑制提供了便利工具。
