Professional memory CD4+ T lymphocytes preferentially reside and rest in the bone marrow

CD4+ T lymphocytes are key to immunological memory, but little is known about the lifestyle of memory CD4+ T lymphocytes. We showed that in the memory phase of specific immune responses to antigens, most of the memory CD4+ T lymphocytes relocated into the bone marrow (BM) within 3-8 weeks after their generation, a process involving integrin a2. Antigen-specific memory CD4+ T lymphocytes expressed Ly-6C to a high degree, unlike most splenic CD44hiCD62L- CD4+ T lymphocytes. In adult mice, more than 80% of Ly-6Chi CD44hiCD62L- memory CD4+ T lymphocytes were in the BM. In the BM, they are located next to IL-7-expressing VCAM-1+ stroma cells, and were in a resting state. Upon challenge with antigen, they rapidly expressed cytokines and CD154 and induced the production of high-affinity antibodies, indicating their functional activity in vivo and marking them as professional memory T helper cells FACSAria sorted CD44highCD62L-CD25- CD4+ T cells of murine (C57BL/6 mice) bone marrow were compared to those of the spleen using Affymetrix GeneChip Mouse Genome 430A 2.0 Array. After total RNA extraction, reverse transcription, cDNA extraction, the biotinylated cRNA was transcribed, fragmented, and 15 µg cRNA hybridized in triplicates for each of the two groups to the GeneChip arrays. Group of bone marrow chips: GSM393497, GSM393940, GSM393941, group of spleen chips: GSM393942, GSM393943, GSM393944. Lists of differentially regulated genes were created using High Performance Chip Data Analysis (HPCDA) with Bioretis database (http://www.bioretis-analysis.de). To see the list of significant genes, go to Bioretis database, register and with your username and password log into the database. Then check under Account, User Details the two boxes Public Chip Rights and Public Analyses. Then select under Comparison, View single results in the window Select an existing Analysis the analysis SPL_294. To find the list of significant genes, click an next, then on Choose an existing parameterset and select first a default increase parameterset (be shure that on row "t-Test EG vs. BG *" in the first 4 left columns <0.05 is included and check the box "* use Bonferroni correction"). Then click on Search only and you will get the list of differentially íncreased genes. Perform the same procedure with a default parameterset for decrease genes. You can get instruction/help about Bioretis database before Login on sheet introduction.