title: A cloned major histocompatibility complex-restricted trinitrophenyl-reactive human helper T cell line that activates B cell subsets via two distinct pathways.
abstract: A cloned, trinitrophenyl (TNP)-specific helper T cell line (TCL), termed E-11, has been established in long-term, interleukin 2-dependent culture and used to study human T helper (Th)-B cell collaboration. Co-culture of E-11 with TNP-modified, but not unmodified or FITC-modified, autologous B cells results in a vigorous, polyclonally plaque-forming cell (PFC) response. E-11 helper activity is not constitutive, but requires antigen-specific, major histocompatibility complex-restricted activation of the TCL cells by interaction with TNP-modified autologous or DR 5+ allogeneic macrophages. Using B cell subsets isolated by discontinuous density gradient cengrifugation as responder populations, we determined that E-11 activates B cell subsets via two distinct mechanisms: (a) E-11 polyclonally activates large B cells in an unrestricted and nonspecific manner; and (b) E-11 preferentially induces a PFC response by TNP-modified small B cells. These results suggest that the large B cell subset is activated by helper signals generated during the Th-antigen-presenting cell interaction, while small B cells require an additional stimulus that is provided by antigen-specific Th-B cell contact.
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology*; D002999:Clone Cells / Q000276:immunology; D000939:Epitopes / Q000276:immunology; D015805:HLA-DR5 Antigen; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D006801:Humans; D008213:Lymphocyte Activation; D008285:Major Histocompatibility Complex; D009578:Nitrobenzenes / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D014301:Trinitrobenzenes / Q000276:immunology*
chemical_list: D000939:Epitopes; D015805:HLA-DR5 Antigen; D000949:Histocompatibility Antigens Class II; D009578:Nitrobenzenes; D014301:Trinitrobenzenes