Anderson J, Melchers F
Proc Natl Acad Sci U S A. 1981 Apr;78(4):2497-501. doi: 10.1073/pnas.78.4.2497.
Cloned murine helper T cells, restricted to the Iab antigens of the major histocompatibility locus and specific for horse erythrocytes as a foreign antigen, produce, in cooperation with antigen and histocompatible adherent cells, soluble factors that replace the helper T cells in their action on B cells. Three types of factors can be distinguished on the basis of molecular weight: proteins having apparent Mr 30,000 (p30) that act antigen- and Ia-nonspecifically as replication- and maturation-inducing factors and proteins having apparent Mr 55,000 (p55) and 125,000 (p125) that act on resting B cells in an Ia-specific, restricted fashion. Neither horse erythrocytes (a T-cell specific antigen) nor p55 and p125, alone or together, stimulate resting B cells to proliferation and maturation. Double occupancy by antigen and p55 or p125, however, renders Ia-compatible, but not Ia-incompatible, resting B cells susceptible to stimulation. The subsequent addition of p30 to these "excited" B cells then results in the proliferation and maturation of clones of horse erythrocyte-specific resting B cells, which then replicate under the stimulatory action of p30. p30 do not bind antigen, nor do they bind anti-Ia or anti-immunoglobulin antibodies. p55 are bound by anti-heavy chain variable region antibodies. p55 are bound by anti-heavy chain variable region antibodies, but not by anti-heavy or anti-light chain constant region antibodies or anti-Ia antibodies. p125 molecules bind horse but not sheep erythrocytes and are bound by anti-heavy chain variable region, but not by anti-heavy or light chain constant region or anti-Ia antibodies. p55 and p125 are likely to be soluble analogues of the antigen-specific, Ia-restricted T-cell receptors of the cloned helper T cells.
克隆的小鼠辅助性T细胞，受主要组织相容性位点的Iab抗原限制，对作为外来抗原的马红细胞具有特异性，它们与抗原和组织相容性贴壁细胞协同作用，产生可溶性因子，这些因子在对B细胞的作用中可替代辅助性T细胞。根据分子量可区分出三种类型的因子：表观分子量为30,000（p30）的蛋白质，它们作为复制和成熟诱导因子，以抗原和Ia非特异性方式起作用；以及表观分子量为55,000（p55）和125,000（p125）的蛋白质，它们以Ia特异性、受限的方式作用于静止B细胞。单独或一起的马红细胞（一种T细胞特异性抗原）、p55和p125都不会刺激静止B细胞增殖和成熟。然而，抗原与p55或p125的双重占据使Ia相容而非Ia不相容的静止B细胞易于受到刺激。随后向这些“被激活的”B细胞中添加p30，会导致马红细胞特异性静止B细胞克隆的增殖和成熟，然后这些克隆在p30的刺激作用下进行复制。p30不结合抗原，也不结合抗Ia或抗免疫球蛋白抗体。p55可被抗重链可变区抗体结合。p55可被抗重链可变区抗体结合，但不能被抗重链或抗轻链恒定区抗体或抗Ia抗体结合。p125分子结合马红细胞而非绵羊红细胞，可被抗重链可变区抗体结合，但不能被抗重链或轻链恒定区抗体或抗Ia抗体结合。p55和p125可能是克隆的辅助性T细胞的抗原特异性、Ia受限的T细胞受体的可溶性类似物。
