CD8 T Cell Subsets

The strongest evidence for the existence of different subsets of CD8 T cells comes from the finding that CD8 T cell clones specific for Mycobacterium kp-ae, derived from the skin biopsies of patients with leprosy, could be divided into two subtypes according to their cytokine 

Control of cytokine release by CD8 T cells shares some features with CD4 T cells, although there is no direct correlation between CD8 subsets and ThI and Th2 cell subsets. Mouse CD8 spleen cells cultured with IL-2, IL-4 and anti-CD3 antibodies produce large amounts of IL-4 (Seder et al., 1992). Rat CD8 T cells cultured with Con A, IL-2, IL-4 and anti-IFN7 generate increased amounts of IL-4 and IU5 mRNA when restimulated with phorbol myristate acetate (PMA) and ionomycin (Noble, MacAry and Kemeny, 1995). However, in contrast to Th2 cells, most alloreac- 

Aalberse, R.C., Van-Der-Gaag, R. and Van-Leeuwen, J. (1983). Serologic aspects of IgG4 antibodies. I. Prolonged immunization results in an IgG4-restricted response. J. Immunol. 130, 722-726. 

Armitagp, R.J., Macduff, B.M., Spriggs, M.K. and Fanslow, W.C. (1993). Human B cell proliferation and Ig secretion induced by recombinant CD40 l nd are modulated by soluble cytokines. J. Immunol. 150, 3671-3680. 

Pochon, S., Graber, P., Jansen, K.U. and Bonnefoy, J.Y. (1992). CD21 is a ligand for CD23 and regulates IgE production. Nature 358, 505-507. 

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TCDD (reviewed in13). However, despite considerable effort, direct effects of TCDD on purified T cells in vitro have not been consistently demonstrated, and direct effects on T cells in vivo are difficult to prove. This issue was recently resolved by studies that compared the effects of TCDD on the graft versus host (GVH) response of T cells obtained from AhR+,+ and AhR C57B1/6 (B6) mice.66 Results showed that the CTL response of grafted AhR- - T cells was resistant to TCDD-induced suppression, while under the same conditions, the CTL response of AhR+,+ T cells was suppressed by > 90%. Furthermore, when CD4+ and CD8+ T cell subsets were isolated from AhR+,+ and AhR- - mice and then recombined prior to grafting, full suppression of the CTL was dependent on AhR expression in both T cell subsets. These results provide the first evidence for the requisite role of the AhR in T cells for TCDD-mediated suppression of T cell responses. Induction of CYP1A1 in purified T cells exposed to TCDD in vitro validates the presence of a functional AhR.6-7... 

Baroncelli S, Panzini G, Geraci A, et al. Longitudinal characterization of CD4, CD8 T-cell subsets and of haematological parameters in healthy newborns of cynomolgus monkeys. Vet Immunol Immunopathol 1997 59(l-2) 141-50. 

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