title: T cell-replacing factor in specific antibody responses to influenza virus by human blood B cells.
abstract: In man, B cell maturation factors obtained from T cells or T cell lines have been shown to induce antibody formation in mitogen or anti-immunoglobulin activated B cells, and in some continuous B cell lines, but the relationships between these factors and B cell differentiation factors in antigen-specific antibody responses is unclear. We have now shown that supernatants from phytohemagglutinin-activated tonsil cells, or from the Gibbon Ape T cell line MLA-144, can substitute for T cells in the specific antibody response by human blood B cells to influenza virus. Thus, T cell-depleted non-rosette-forming (E-) cells prepared from peripheral blood mononuclear cells made antibody when cultured with antigen and factor together, whereas control cultures of E- cells with either antigen or factor alone did not. Moreover, E- cells cultured with factor and influenza virus strain A/X31 made antibody to A/X31, but not the non-cross-reacting strain, B/HK (and vice versa) showing that the response was antigen specific. The activity in these supernatants, therefore, fulfilled the functional definition of T cell-replacing factor (TRF). The possibility that interleukin 2 (IL 2) present in the TRF-containing supernatants was expanding residual T cells in the E- preparations to provide normal T cell help was excluded in three different ways. First, E- cells depleted of T (Leu4+) cells to undetectable levels made normal amounts of antibody when cultured with antigen and TRF. Secondly, a limiting dilution technique was employed to show that help in cultures of E- cells and TRF was not mediated by antigen-specific T helper cells. Thirdly, TRF-containing supernatants depleted of IL2 retained activity, whereas purified IL2 was inactive. Preliminary purification of TRF by gel filtration on Ultrogel AcA54 columns showed that all the activity eluted in a single peak between 35 000 and 43 000 molecular weight. This distinguishes human TRF from IL 2 and from other B cell maturation factors with a molecular weight range of 15 000-20 000 which act on continuous B cell lines. In addition to TRF, supernatants from phytohemagglutinin-activated tonsils also contained a factor which could induce polyspecific IgM production, but only in cultures containing significant numbers of T cells. This additional activity may have been due to IL 2, and provides an explanation for the apparent T cell-dependent effects sometimes observed in experiments designed to test B cell differentiation factors on T cell-depleted normal B cells.
authors.forename: R E
authors.initials: RE
authors.lastname: Callard
authors.forename: R J
authors.initials: RJ
authors.lastname: Booth
authors.forename: M H
authors.initials: MH
authors.lastname: Brown
authors.forename: G W
authors.initials: GW
authors.lastname: McCaughan
mesh_terms: D000914:Antibodies, Viral / Q000096:biosynthesis*; D000918:Antibody Specificity; D000921:Antibody-Producing Cells / Q000276:immunology / Q000378:metabolism*; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D002850:Chromatography, Gel; D000939:Epitopes / Q000276:immunology; D006801:Humans; D009980:Influenza A virus / Q000276:immunology*; D007376:Interleukin-2 / Q000502:physiology; D015848:Interleukin-5; D008222:Lymphokines / Q000302:isolation & purification / Q000502:physiology*; D008970:Molecular Weight; D012397:Rosette Formation; D013601:T-Lymphocytes / Q000276:immunology / Q000502:physiology
chemical_list: D000914:Antibodies, Viral; D000939:Epitopes; D007376:Interleukin-2; D015848:Interleukin-5; D008222:Lymphokines