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T cell Activation in Vivo Carrie Miceli May 16, 2005

Tracking antigen specific T cell dynamics in vivo. The problem: frequency of an ag specific T cell 1/105-1/106The dream solution: TCR transgenic mice with monoclonal specificity Reality sets in, these mice are not normalAntigen specific T cells are too abundant, no room for all cells to expand pr

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T cell Activation in Vivo Carrie Miceli May 16, 2005

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    1. T cell Activation in Vivo Carrie Miceli May 16, 2005 Assigned reading: Drew M. Catron, Andrea A. Itano, Kathryn A. Pape, Daniel L. Mueller, and Marc K. Jenkins Visualizing the First 50 Hr of the Primary Immune Response to a Soluble Antigen Immunity 2004 21: 341-347. Additional Reading: Jenkins et al., In Vivo Activation of Antigen Specific CD4 T cells. Annual Review of Immunology 2001 Reinhardt and Jenkins Whole-body Analysis of T cell Responses Current Opinion in Immunology 2003 15:366-371 Germain and Jenkins. In vivo antigen presentation. Current Opinion in Immunology 2003 16: 120-125

    2. Tracking antigen specific T cell dynamics in vivo The problem: frequency of an ag specific T cell 1/105-1/106 The dream solution: TCR transgenic mice with monoclonal specificity Reality sets in, these mice are not normal Antigen specific T cells are too abundant, no room for all cells to expand properly Initial expansion followed by immediate crash no productive immunity The real solution (Marc Jenkins) Adoptive transfer of TCR transgenic T cells into wt congenic Seed TCR tg T cells at 0.3% (still not normal) Availability of anti-TCR clonotypic antibody allows for identification of TCR tg T cells Get expansion, homing, and differentiation of TCR tg T cells in response to specific antigen MHC/peptide tetramers -an alternate solution (mark davis)

    4. Histology allows for in situ detection; flow allows for quantitation; activation and differentiation markers Transferred T cells can be from knockout X TCR transgene Recipient can be knockout to determine APC or tissue requirements Can also adoptively transfer APC or specific B cells Can take advantage of congenic strains of allelic CD45, CD8, or thy-1 mice Can track number of cell divisions using CFSE Can manipulate route of antigen delivery Conditions of activation or inactivation (adjuvent or site and dose)

    5. CFSE allows determination of number of cell divisions by flow cytometry. One can stimulate and monitor in vitro; adoptively transfer and monitor in vivo fate; or transfer and both stimulate and track fate in vivo

    6. Question answered using this approach. Where do T cells first encounter antigen? What are the molecular requirements for activation, homing to B cell zones, B cell help? Do T cells die after several rounds of division? Do they home to the tissues? Do they become memory T cells? Are those that home to tissues different from those that stay in lymphoid tissues, die or become memory Ts?

    11. DC Movie/subcuteneous injection T cell in paracortex/T cell zone first encounters antigen (4 hrs post injection) on a LN resident Langerhans cell (migrated there earlier)…both antigen specific and non specific give it a try T cell activated to express CD69 and lymphokines (and perhaps chemokine receptor responsible for interaction with interstitial dendritic cells) Second wave of antigen presentation at 18 hrs by newly immigrated tissue/interstitial dendritic cells T cells activated in the first wave specifically migrate to and interact with these immigrated interstitial dendritic cells and are stimulated to divide Some leave to tissues, some migrate to B cell follicle to help

    12. In Situ Detection of IL-2 Production by Antigen-Specific CD4 T Cells

    18. Whole mouse movie Spleen entry chemokine dependent, CD62L-independent Lymph node entry CCR7 dependent; CD62L dependent Free antigen flows through afferent lymph into T Cell area, taken up by resident Langerhans cells Dermal DC take up antigen at the injection site, migrate to T cell area in response to IL-1, TNF Naďve T cell activated by resident langerhans cell to express CD69, produce IL-2, more if B7 induced on APC Activated T cell seeks out migrating dermal dendritic cells, is reactivated T cells divide; some many times some few times T cells leave lymph node to efferent lymph Highly divided T cells lose CD62L, gain fPSGL-1 Highly dividing tissue homing (lungs and other tissues as well as specifically to site of injection). After APC death many T cells die there. Nonlymphoid seeking and effector lymphokine producing less dividing lymph node seeking; retain CD62L, produce IL-2

    19. A productive primary CD4 T cell response to antigen in the presence of adjuvant-induced inflammation Jenkins Annual Rev of Immunol..2001

    21. Tracking antigen specific responses with MHC/tetramers

    22. Science 1996 Oct Phenotypic analysis of antigen-specific T lymphocytes Altman JD…... Davis MM.

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