title: More antigen-dependent CD4(+) T cell / CD4(+) T cell interactions are required for the primary generation of Th2 than of Th1 cells.
abstract: Mechanisms controlling the Th1 / Th2 phenotype of a primary immune response are often discussed assuming that the generation of Th1 and Th2 cells from the common CD4(+) precursor T helper (pTh) involves an interaction of this pTh cell with an antigen-presenting cell (APC) in the form of a two-cell interaction. Other studies suggest that the outcome of this two-cell interaction is modified by the presence of other T cells. No study has analyzed primary immune responses generated in normal, non-TcR transgenic mice, following the administration of a non-infectious antigen administered without adjuvant. We show that the Th1 / Th2 phenotype of such a primary response, generated in lethally irradiated recipients reconstituted with a variety of unprimed spleen cells, depends conjointly on the amount of antigen and number of unprimed syngeneic CD4(+) T cells present, with higher amounts and numbers favoring the generation of Th2 cells. Our observations show how these quantitative variables control in an interdependent manner the Th1 / Th2 phenotype of a primary immune response, and bear upon the mechanism by which this phenotype is determined.
authors.affiliation: Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Canada.
authors.forename: N
authors.initials: N
authors.lastname: Ismail
authors.forename: P A
authors.initials: PA
authors.lastname: Bretscher
mesh_terms: D000818:Animals; D000941:Antigens / Q000276:immunology; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000528:radiation effects; D002478:Cells, Cultured; D004912:Erythrocytes / Q000276:immunology; D016130:Immunophenotyping; D015847:Interleukin-4 / Q000096:biosynthesis; D051379:Mice; D008808:Mice, Inbred CBA; D013154:Spleen / Q000166:cytology / Q000276:immunology / Q000528:radiation effects; D018417:Th1 Cells / Q000276:immunology* / Q000528:radiation effects; D018418:Th2 Cells / Q000276:immunology* / Q000528:radiation effects
chemical_list: D000941:Antigens; D015847:Interleukin-4