Migration pathways of CD4 T cell subsets in vivo: the CD45RC^- subset enters the thymus via α₄ integrin-VCAM-1 interaction

Abstract

The present investigation examines the localization and migration of purified T cell subsets in comparison with B cells, CD8 T cells and CD4+ CD8- single-positive thymocytes. CD4 T cell subsets in the rat are defined by mAb MRC OX22 (anti-CD45RC), which distinguishes resting CD4 T cells (CD45RC+) from those (CD45RC-) which have encountered antigen in the recent past--subpopulations often referred to as 'naive' and 'memory'. Purified, 51Cr-labelled CD45RC+ CD4 T cells broadly reflected the migration pattern of CD8 T cells and B cells. Early localization to the spleen was followed by a redistribution to mesenteric lymph nodes (MLN) and cervical lymph nodes (CLN), B cells migrating at a slightly slower tempo. There was almost no localization of these subpopulations to the small or large intestine [Peyer's patches (PP) excluded]. In contrast, CD45RC- CD4 T cells (indistinguishable in size from the CD45RC+ subset) localized in large numbers to the intestine; they were present here at the earliest time point (0.5 h), persisted for at least 48 h but did not accumulate, indicating a rapid exit. Numerically, localization of CD45RC- CD4 T cells in the MLN could be accounted for entirely by afferent drainage from the intestine. Unexpectedly, CD45RC- CD4 T cells (but not other subsets) localized and accumulated in the thymus. In vivo treatment with mAb HP2/1 against the integrin alpha 4 subunit inhibited almost entirely CD45RC- CD4 T cell migration into the PP (98.1%), intestine (87.1%), MLN (89.1%) and thymus (93.5%); migration into the CLN was only reduced by half. To distinguish between recognition of MAdCAM-1 and VCAM-1 by alpha 4-containing integrins, recipients were treated with mAb 5F10 against rat VCAM-1. Except for the thymus and a small reduction in CLN, localization of CD45RC- CD4 T cells was unaffected; entry to the thymus was almost completely blocked (92.3%) by anti-VCAM-1. The results indicated (i) that CD45RC- CD4 T cells alone showed enhanced localization to the gut and PP, probably via alpha 4 beta 7-MAdCAM-1 interaction; (ii) that many CD45RC- cells entered non-mucosal LN independently of alpha 4 integrin or VCAM-1; and (iii) that entry of mature recirculating CD45RC- CD4 T cells into the thymus across thymic endothelium was apparently regulated by alpha 4 integrin-VCAM-1 interaction.

The Effect of Antigen Stimulation on the Migrationof Mature T Cells from the Peripheral Lymphoid Tissuesto the Thymus

“…There Was clearly an increase in the number of cells which migrated into the thymus following antigen-specific T cell activation in the periphery, confirming the findings of earlier studies (Naparstek et al, 1982;Fink et al, 1984;Agus et al, 1991;Bell et al, 1995;Westermann et al, 1996). This increase amounted to about 16 to 20-fold 3 days after injection with peptide.…”

“…More recently, it was shown that blasts (generated in parent F combinations) homed to the thymus, and represented approximately 0.4% of mature T thymocytes, although the rate of homing was greatly increased by irradiation of hosts (Agus et al, 1991). Others have shown that, compared to 'naive' CD4 + T cells, there is a preferential accumulation of antigen-experienced T cells in the rat thymus (Bell et al, 1995;Westerman et al, 1996). As is the case for 'normal' peripheral T cells (Hirokawa et al, 1989), accumulation of activated cells within the thymus is largely restricted to the medulla (Pabst and Binns, 1989;Agus et al, 1991;Westermann et al, 1996).…”

Thymic emigrants isolated by a new method possess unique phenotypic and functional properties

“…One limitation of the method of thymus FITC injection is that recirculating mature lymphocytes, and particularly those that have been previously activated, continuously enter the thymus as shown in many studies [6][7][8][9][10][11][12][13][14][15] and would also be labeled. Many of the FITC-labeled cells that leave the thymus and are detected peripherally could therefore be mature recirculating T cells, rather than cells that recently matured in the thymus.…”

Immune cell-derived beta-endorphin. Production, release, and control of inflammatory pain in rats.

“…To discriminate between END-containing memory versus naive T cells, cells from LN and the circulation were collected as described previously. T-helper cells (CD4) are comprised of two subsets: naive and memory cells (18). Since antibodies against rat memory T cells were not available, we first stained these cells with an antibody against END and then with an antibody against all T-helper cells (CD4 ϩ ).…”

“…In another experiment, we stained for END and for naive T cells (CD45RC ϩ ). We hypothesized that if END-containing cells stain for CD4 but infrequently stain for CD45RC, then END ϩ /CD4 ϩ cells would be predominantly END-containing memory-type T cells (18). Immune cells (5 ϫ 10 6 cells/tube) were examined for coexistence of CD4 and END by double staining with FITC-preconjugated anti-CD4 (W3/25) and a rabbit antibody to END, followed by an IgG secondary goat anti-rabbit antibody preconjugated with Texas red.…”