title: Activation of human CD4+45RA+ T cells using B cells as accessory cells.
abstract: Human naive CD4+ T cells, as defined by expression of CD45RA and lack of CD45R0, can be activated in vitro using B cells as accessory cells. CD4+CD45RA+ T cells proliferate, as determined by [3H]thymidine or bromodeoxyuridine (BrdU) incorporation, after activation with the superantigen staphylococcal enterotoxin A (SEA) presented by major histocompatibility complex class II-expressing B cells. The identity of the responding cells as being CD45RA+ and not contaminating CD45R0+ T cells was determined by FACS analysis, showing that purified CD45RA-expressing T-helper cells went into S phase and progressively acquired expression of the CD45R0 isoform while simultaneously losing expression of the CD45RA isoform. Cultivation of the CD4+ T-cell subsets under limiting dilution conditions supported these findings and revealed that (i) the frequency of responding cells in the CD45RA+ population was equal to or higher than in the CD45R0+ subset and (ii) that the number of CD45R0+ cells possibly contaminating the CD45RA population was too low to be able to account for the response observed.
authors.affiliation: BioInvent International AB, Lund, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Kristensson
authors.forename: L
authors.initials: L
authors.lastname: Kristensen
authors.forename: C A
authors.initials: CA
authors.lastname: Borrebaeck
authors.forename: R
authors.initials: R
authors.lastname: Carlsson
mesh_terms: D000938:Antigen-Presenting Cells / Q000502:physiology*; D001402:B-Lymphocytes / Q000502:physiology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D004768:Enterotoxins / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D017493:Leukocyte Common Antigens / Q000032:analysis; D008213:Lymphocyte Activation / Q000276:immunology*; D011043:Pokeweed Mitogens / Q000276:immunology
chemical_list: D004768:Enterotoxins; D011043:Pokeweed Mitogens; C026066:enterotoxin A, Staphylococcal; D017493:Leukocyte Common Antigens