T cell-dependent activation of resting B cells: requirement for both nonspecific unrestricted and antigen-specific Ia-restricted soluble factors.

作者：James Anderson, Fritz Melchers · 发表于：Proceedings of the National Academy of Sciences · 年份：1981 · DOI：10.1073/pnas.78.4.2497 · 被引用次数：113 · 研究领域：T-cell and B-cell Immunology、Monoclonal and Polyclonal Antibodies Research、Immunotherapy and Immune Responses

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 s...