The T Cell Chronicle

1. The T Cell Chronicle INTRACELLULAR CYTOKINES PROLIFERATION ELISPOT TcR SPECTRATYPING NUMBER IFN-PE-A FITC-A CFSE FITC-A CFSE-FITCA Vol. 1  Issue 3  Spring 2008 ASSESSMENT OF T CELL RECOMBINANT EXCISION CIRCLES (TRECS) Reconstitution of the immune system after high dose chemotherapy can be complex process involving both homeostatic expansion of residual mature T cells as well as the emergence of new naive T cells from the thymus. Methodology is available in the Human Immunology Core to identify recent thymic emigrants or naïve T cells. Thymocytes rearrange their T cell receptor (TCR) genes during development. Upon completion of TCR gene rearrangement, a non-replicating excision circle is formed that can be easily assessed to identify these cells as recent thymic emigrants or naïve T cells. The results in Figure A track the recovery of lymphocytes after high dose chemotherapy and the relative expression of TRECS. Here, reconstitution clearly involves newly emigrated T cells from the thymus. It is commonly thought that many CD3+CD4+Foxp3+ regulatory T cells Contact Information Allan D. Hess, Ph.D. - Director (410) 955-8975 E-mail: adhess@jhmi.edu. Ferdynand Kos, Ph.D. (410) 502-3195 E-mail: fkos1@jhmi.edu. Christopher Thoburn Sr. Research Tech (410) 955-8568 E-mail:cthoburn@jhmi.edu. emerge directly from the thymus rather than developing in the periphery. Analysis of the lymphocytes on day 30 reveals a significant number of CD3+CD4+Foxp3+ Tregs present in the peripheral blood (Figure B). Interestingly, very few of these cells had T cell recombinant excision circles (Figure C) suggesting that they may have been driven by antigen or expanded by homeostatic cytokines. On the other hand, a large number of TRECs were detected in the non-regulatory T cell compartment indicating that these cells are largely composed of recent thymic emigrants. TREC analysis can be a very powerful technique to explore important questions regarding the reconstitution of the immune system. TREC analysis is routinely performed in the Human Immunology Core Laboratory. For more info contact us at our web site or give us a call. http://humanimmunology.onc.jhmi.edu. In our next issue Multiplex Analysis of Cytokines For Consultation Services, please contact Allan D. Hess, Ph.D. at (410) 955-8975 T h e T C e l l C h r o n i c l e  SPRING 2 0 0 8