We plan to test the hypothesis that gamma-delta T cells play an important role in tolerance to exogenous and endogenous antigens. This idea is based on our experiments determining how CD8+ T cells down regulate immune responses. We have shown that exogenous antigens, such as ovalbumin (OVA) mixed with complete Freund's adjuvant (CFA) primes OVA-specific, MHC class I restricted, CD8+ CTL. Transfer of these CTL to naive, syngeneic recipients inhibited OVA-specific responses suggesting that CTL could account for some of the suppressor activities of CD8+ T cells. To test whether CTL were involved in a typical model involving suppression, oral tolerance to OVA was studied. We found that oral administration of OVA did not prime CTL but rather inhibited the priming of CTL. in addition, CD8+ splenic T cells from tolerant mice transferred tolerance to naive mice suggesting that not all suppressors are CTL. Moreover, pretreatment of mice with anti-gamma-delta TcR antibody prevented tolerance induction by OVA and reversed self tolerance to insulin. Indirect evidence suggests that anti-gamma-delta antibody interferes with tolerance induction by depleting gamma-delta T cells. Also, oral administration of OVA failed to induce tolerance in gamma-delta knock out mice providing additional support for the interpretation that gamma-delta T cells play an essential role in tolerance induction. The goal of this project is to determine the role of gamma-delta T cells in tolerance using OVA as an extrinsic or an intrinsic antigen with particular emphasis on OVA as a tumor antigen. We will test whether the CD8+ suppressor T cells induced by oral administration of OVA are gamma- delta T cells or whether gamma-delta T cells regulate the activation of CD8+ suppressor T cells. We will determine whether gamma-delta T cells are OVA-specific and produce T cell clones or hybridomas to study their receptors. The role of gamma-delta T cells in self-tolerance also will be studied using transgenic (Tg) mice expressing the OVA gene. We will determine whether these mice are tolerant to OVA in CFA and whether anti- gamma-delta antibody reverses tolerance. Tg mice will be given oral OVA to determine whether gamma-delta T cells and/or CD8+ suppressor T cells are tolerant. The possibility that gamma-delta T cells could be involved in the failure of tumors to be rejected will be tested using EL4 cells expressing the OVA gene as a tumor model. The effect of tolerance or immunity to OVA on tumor rejection will be evaluated and the effect of anti-gamma-delta antibody on tumor rejection will be assessed in normal and OVA Tg mice. The ability of tumors transfected with co-stimulators to overcome tolerance and induce rejection will be compared in normal and Tg mice.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA070372-02
Application #
2414453
Study Section
Experimental Immunology Study Section (EI)
Project Start
1996-05-01
Project End
1999-04-30
Budget Start
1997-05-01
Budget End
1998-04-30
Support Year
2
Fiscal Year
1997
Total Cost
Indirect Cost
Name
Emory University
Department
Pathology
Type
Schools of Medicine
DUNS #
042250712
City
Atlanta
State
GA
Country
United States
Zip Code
30322
Zimring, James C; Kapp, Linda M; Yamada, Masahisa et al. (2005) Regulation of CD8+ cytolytic T lymphocyte differentiation by a cholinergic pathway. J Neuroimmunol 164:66-75
Kapp, Judith A; Kapp, Linda M; McKenna, Kyle C (2004) Gammadelta T cells play an essential role in several forms of tolerance. Immunol Res 29:93-102
Kapp, Judith A; Kapp, Linda M; McKenna, Kyle C et al. (2004) gammadelta T-cell clones from intestinal intraepithelial lymphocytes inhibit development of CTL responses ex vivo. Immunology 111:155-64
Zimring, James C; Levery, Steven B; Kniep, Bernhard et al. (2003) CD75s is a marker of murine CD8(+) suppressor T cells. Int Immunol 15:1389-99
Ma, H; Kapp, J A (2001) Peptide affinity for MHC influences the phenotype of CD8(+) T cells primed in vivo. Cell Immunol 214:89-96
Ma, H; Kapp, J A (2000) Antigenic epitopes regulate the phenotype of CD8+ CTL primed by exogenous antigens. J Immunol 164:5698-703
Ke, Y; Ye, K; Grossniklaus, H E et al. (2000) Noscapine inhibits tumor growth with little toxicity to normal tissues or inhibition of immune responses. Cancer Immunol Immunother 49:217-25
Ke, Y; Ma, H; Kapp, J A (1998) Antigen is required for the activation of effector activities, whereas interleukin 2 Is required for the maintenance of memory in ovalbumin-specific, CD8+ cytotoxic T lymphocytes. J Exp Med 187:49-57
Dombrowski, K E; Ke, Y; Brewer, K A et al. (1998) Ecto-ATPase: an activation marker necessary for effector cell function. Immunol Rev 161:111-8
Kapp, J A; Ke, Y (1997) The role of gammadelta TCR-bearing T cells in oral tolerance. Res Immunol 148:561-7

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