Two groups of porcine TCRgammadelta+ thymocytes behave and diverge differently.
Developmental pathways of gammadelta T cells are still unknown, largely because of the absence of recognized lineage-specific surface markers other than the TCR. We have shown that porcine gammadelta thymocytes can be divided into 12 subsets of the following two major groups: 1) CD4(-) gammadelta thymocytes that can be further subdivided according to their CD2/CD8alphaalpha phenotype, and 2) CD4(+) gammadelta thymocytes that are always CD1(+)CD2(+)CD8alphabeta(+) and have no counterpart in the periphery. In this study, we have analyzed gammadelta thymocyte subsets with respect to behavior during cultivation, cell cycle status, and lymphocyte-specific transcripts. The group of CD4(-) gammadelta thymocytes gives rise to all gammadelta T cells found in the periphery. Proliferating CD2(+)CD8(-)CD1(+)CD45RC(-) gammadelta thymocytes are a common precursor of this group. These precursors differentiate into CD2(+)CD8alphaalpha(+), CD2(+)CD8(-), and CD2(-)CD8(-) gammadelta T cell subsets, which subsequently mature by loss of CD1 and by eventual gain of CD45RC expression. In contrast, the group of CD4(+) gammadelta thymocytes represents transient and independent subsets that are never exported from thymus as TCRgammadelta(+) T cells. In accordance with the following findings, we propose that CD4(+)CD8alphabeta(+) gammadelta thymocytes extinguish their TCRgammadelta expression and differentiate along the alphabeta T cell lineage program: 1) CD4(+) gammadelta thymocytes are actively dividing; 2) CD4(+) gammadelta thymocytes do not die, although their numbers decreased with prolonged cultivation; 3) CD4(+) gammadelta thymocytes express transcripts for RAG-1, TdT, and TCRbeta; and 4) CD4(+) gammadelta thymocytes are able to alter their phenotype to TCRalphabeta(+) thymocytes under appropriate culture conditions.
Sinkora
Marek
M
Department of Immunology and Gnotobiology, Institute of Microbiology, Academy of Sciences of the Czech Republic, Doly 183, 549 22 Nový Hrádek, Czech Republic. Marek.Sinkora@worldonline.cz
Sinkorová
Jana
J
Cimburek
Zdenek
Z
Holtmeier
Wolfgang
W
D000818:Animals; D018949:Antigens, CD1 / Q000378:metabolism; D017209:Apoptosis; D018801:CD2 Antigens / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D002454:Cell Differentiation / Q000276:immunology*; D019070:Cell Lineage / Q000276:immunology*; D002465:Cell Movement; D002478:Cells, Cultured; D017493:Leukocyte Common Antigens / Q000276:immunology / Q000378:metabolism; D010641:Phenotype; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000235:genetics / Q000276:immunology*; D013552:Swine / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology* / Q000276:immunology*; D014158:Transcription, Genetic / Q000235:genetics
D018949:Antigens, CD1; D018801:CD2 Antigens; D016692:Receptors, Antigen, T-Cell, gamma-delta; D017493:Leukocyte Common Antigens