Cellular requirements for the activation and proliferation of ruminant gammadelta T cells.
Requirements for the activation and proliferation of gammadelta T cells were investigated. Maximum numbers of gammadelta T cells expressed the IL-2R alpha-chain after 6-h Con A stimulation in peripheral blood, efferent lymph, and afferent lymph. In comparison, IL-2R alpha-chain expression on CD4 T cells only reached maximum levels in response to Con A stimulation in peripheral blood and afferent lymph populations. Analysis of enriched gammadelta T cells demonstrated that Con A-induced expression of the IL-2R alpha-chain was independent of APC. Together, these data suggest that the requirements for gammadelta T cell activation are less stringent than those for alphabeta T cell activation. Unfractionated peripheral blood, efferent lymph, and afferent lymph cell populations proliferated in response to Con A alone. In contrast, enriched gammadelta T cells (CD4/CD8 depleted) from efferent lymph did not proliferate in response to Con A alone, but required the addition of IL-2. This requirement for exogenous IL-2 could be overcome by the addition of dendritic cells purified from afferent lymph. These results suggested that gammadelta T cells required costimulatory signals provided by APC to ensure the production of sufficient IL-2 to drive proliferation. CD28 and CTLA-4 mRNA were detected in efferent lymph and afferent lymph populations containing CD4 and CD8 T cells stimulated with Con A and IL-2 or with Con A alone, respectively. In contrast, negligible levels of these mRNA species were detected in efferent and afferent lymph populations devoid of CD4 and CD8 T cells. These results suggest that ovine gammadelta T cells may use alternative costimulatory pathways.
Hanrahan
C F
CF
Center for Animal Biotechnology, University of Melbourne School of Veterinary Science, Australia.
Kimpton
W G
WG
Howard
C J
CJ
Parsons
K R
KR
Brandon
M R
MR
Andrews
A E
AE
Nash
A D
AD
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002455:Cell Division / Q000276:immunology; D003208:Concanavalin A / Q000276:immunology; D007376:Interleukin-2 / Q000276:immunology; D008213:Lymphocyte Activation; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000276:immunology*; D015375:Receptors, Interleukin-2 / Q000276:immunology; D012418:Ruminants; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology*
D007376:Interleukin-2; D016692:Receptors, Antigen, T-Cell, gamma-delta; D015375:Receptors, Interleukin-2; D003208:Concanavalin A