Jayant Thatte

Preferential migration of effector CD8 + T cells into the interstitium of the normal lung

The respiratory tract is a primary site of infection and exposure to environmental antigens and an important site of memory T cell localization. We analyzed the migration and retention of naive and activated CD8+ T cells within the noninflamed lungs and quantitated the partitioning of adoptively transferred T cells between the pulmonary vascular and interstitial compartments. Activated but not naive T cells were retained within the lungs for a prolonged period. Effector CD8+ T cells preferentially egressed from the pulmonary vascular compartment into the noninflamed pulmonary interstitium. T cell retention within the lung vasculature was leukocyte function antigen-1 dependent, while the egress of effector T cells from the vascular to the interstitium functions through a pertussis toxin-sensitive (PTX-sensitive) mechanism driven in part by constitutive CC chemokine ligand 5 expression in the lungs. These results document a novel mechanism of adhesion receptor- and pulmonary chemokine-dependent regulation of the migration of activated CD8+ T cells into an important nonlymphoid peripheral site (i.e., the normal/noninflamed lung).

Endogenous Oocyte Antigens Are Required for Rapid Induction and Progression of Autoimmune Ovarian Disease Following Day-3 Thymectomy

Female (C57BL/6×A/J)F1 mice undergoing thymectomy on day 3 after birth (d3tx) developed autoimmune ovarian disease (AOD) and autoimmune disease of the lacrimal gland. As both were prevented by normal adult CD25+ T cells, regulatory T cell depletion is responsible for d3tx diseases. AOD began as oophoritis at 3 wk. By 4 wk, AOD progressed to ovarian atrophy with autoantibody response against multiple oocyte Ag of early ontogeny. The requirement for immunogenic endogenous ovarian Ag was investigated in d3tx female mice, d3tx male mice, and d3tx neonatally ovariectomized (OX) females. At 8 wk, all mice had comparable lacrimalitis but only those with endogenous ovaries developed AOD in ovarian grafts. The duration of Ag exposure required to initiate AOD was evaluated in d3tx mice OX at 2, 3, or 4 wk and engrafted with an ovary at 4, 5, or 6 wk, respectively. The mice OX at 2 wk did not have oophoritis whereas ∼80% of mice OX at 3 or 4 wk had maximal AOD, thus Ag stimulus for 2.5 wk following d3tx is sufficient. AOD progression requires additional endogenous Ag stimulation from the ovarian graft. In mice OX at 3 wk, ovaries engrafted at 5 wk had more severe oophoritis than ovaries engrafted at 6 or 12 wk; moreover, only mice engrafted at 5 wk developed ovarian atrophy and oocyte autoantibodies. Similar results were obtained in mice OX at 4 wk. Thus endogenous tissue Ag are critical in autoimmune disease induction and progression that occur spontaneously upon regulatory T cell depletion.

Differential Requirements for Core2 Glucosaminyltransferase for Endothelial L-Selectin Ligand Function In Vivo

L-selectin is a calcium-dependent lectin on leukocytes mediating leukocyte rolling in high endothelial venules and inflamed microvessels. Many selectin ligands require modification of glycoproteins by leukocyte core2 β1,6-N-acetylglucosaminyltransferase (Core2GlcNAcT-I). To test the role of Core2GlcNAcT-I for L-selectin ligand biosynthesis, we investigated leukocyte rolling in venules of untreated and TNF-α-treated cremaster muscles and in Peyer’s patch high endothelial venules (HEV) of Core2GlcNAcT-I null (core2−/−) mice. In the presence of blocking mAbs against P- and E-selectin, L-selectin-mediated leukocyte rolling was almost completely abolished in cremaster muscle venules of core2−/− mice, but not littermate control mice. By contrast, leukocyte rolling in Peyer’s patch HEV was not significantly different between core2−/− and control mice. To probe L-selectin ligands more directly, we injected L-selectin-coated beads. These beads showed no rolling in cremaster muscle venules of core2−/− mice, but significant rolling in controls. In Peyer’s patch HEV, beads coated with a low concentration of L-selectin showed reduced rolling in core2−/− mice. Beads coated with a 10-fold higher concentration of L-selectin rolled equivalently in core2−/− and control mice. Our data show that endothelial L-selectin ligands relevant for rolling in inflamed microvessels of the cremaster muscle are completely Core2GlcNAcT-I dependent. In contrast, L-selectin ligands in Peyer’s patch HEV are only marginally affected by the absence of Core2GlcNAcT-I, but are sufficiently functional to support L-selectin-dependent leukocyte rolling in Core2GlcNAcT-I-deficient mice.

A Role for the Region Encompassing the c″ Strand of a TCR Vα Domain in T Cell Activation Events

The distinct strand topology of TCR Vα domains results in a flatter surface in the region encompassing the c″ strand than the corresponding region in Ig V domains. In the current study a possible role for this region in T cell activation has been investigated by inserting a potential glycosylation site at Vα residue 82. This residue is in proximity to the c″ strand and distal to the putative interaction site for cognate peptide:MHC ligand. An additional N-linked carbohydrate at this position would create a protrusion on the Vα domain surface, and this may interfere with TCR aggregation and/or recruitment of signaling molecules. The modified TCR has been expressed in transfected T cells, and the phenotype following stimulation has been compared with that of cells expressing the wild-type TCR. The mutation has significant effects on activation-induced cell death and TCR internalization, but, unexpectedly, does not affect IL-2 secretion. Furthermore, analyses with tetrameric, peptide:MHC class II complexes suggest that the mutation decreases the ability of the TCR to aggregate into a configuration compatible with avid binding by these multivalent ligands.