title: Analysis of human CD4 T lymphocyte proliferation induced by porcine lymphoblastoid B cell lines.
abstract: BACKGROUND
  This study was undertaken to characterize the two porcine lymphoblastoid cell lines L23 and L35, derived from a pig inoculated by the retrovirus Tsukuba-1, and to determine how they induce a strong human lymphocyte proliferation.
  
  
  METHODS
  Phenotypic characterization was performed by flow cytometry and reverse transcriptase-polymerase chain reaction analyses. Xenogeneic mixed lymphocyte reactions (XMLR) were performed using unfractionated human peripheral blood mononuclear cells (huPBMC) and purified CD4+ T lymphocytes as responding cells, in the presence of blocking antibodies and fusion proteins.
  
  
  RESULTS
  The immunoglobulin genes were demonstrated to be rearranged in L23 and L35 cell lines, in agreement with the expression of a B cell phenotype. Both induced a similar proliferation of huPBMCs and purified human CD4+ lymphocytes from adult or cord blood (naïve cells). Proliferation of CD4+ T lymphocytes was completely blocked by anti-SLA-DR plus anti-SLA-DQ mAbs, excluding human lymphocyte transformation by porcine viruses. The frequency of proliferative precursors was inconsistent with that induced by a retroviral superantigen but similar to classical direct xenoantigen presentation as observed with other porcine antigen-presenting cells. Extensive analysis of costimulatory signals led to the identification of the CD28 pathway, in agreement with membrane expression of B7 molecules on L23 and L35 cells, and of the CD2 pathway in L35 cells.
  
  
  CONCLUSIONS
  These two porcine lymphoblastoid cell lines have been further characterized and clearly identified as belonging to the B cell lineage. By expressing major histocompatibility complex class II antigens and costimulatory molecules, they induce a vigorous proliferative response of human CD4+ lymphocytes through a direct presentation pathway.
authors.affiliation: EA 3249 Cellules Hématoponaïétiques, Hémostase et Greffe and IFR 120 Imagerie et Exploration Fonctionnelles, Université François Rabelais, Tours cedex, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Bonenfant
authors.forename: Isabelle
authors.initials: I
authors.lastname: Vallée
authors.forename: Jishan
authors.initials: J
authors.lastname: Sun
authors.forename: Angélique
authors.initials: A
authors.lastname: Brossay
authors.forename: Gilles
authors.initials: G
authors.lastname: Thibault
authors.forename: Jean Maurice
authors.initials: JM
authors.lastname: Guillaumin
authors.forename: Yvon
authors.initials: Y
authors.lastname: Lebranchu
authors.forename: Pierre
authors.initials: P
authors.lastname: Bardos
authors.forename: J E
authors.initials: JE
authors.lastname: Butler
authors.forename: Hervé
authors.initials: H
authors.lastname: Watier
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology*; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology*; D002450:Cell Communication / Q000276:immunology*; D002455:Cell Division / Q000276:immunology; D002460:Cell Line; D005312:Fetal Blood / Q000166:cytology; D006801:Humans; D016130:Immunophenotyping; D008213:Lymphocyte Activation / Q000276:immunology; D008297:Male; D008871:Microvilli / Q000276:immunology; D013556:Swine, Miniature; D014183:Transplantation, Heterologous / Q000276:immunology*