Analysis of human CD4 T lymphocyte proliferation induced by porcine lymphoblastoid B cell lines.
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.
Bonenfant
Christine
C
EA 3249 Cellules Hématoponaïétiques, Hémostase et Greffe and IFR 120 Imagerie et Exploration Fonctionnelles, Université François Rabelais, Tours cedex, France.
Vallée
Isabelle
I
Sun
Jishan
J
Brossay
Angélique
A
Thibault
Gilles
G
Guillaumin
Jean Maurice
JM
Lebranchu
Yvon
Y
Bardos
Pierre
P
Butler
J E
JE
Watier
Hervé
H
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*