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The recirculation of lymphocytes through the intestinal mucosa is important for specific immune defense, but the origin and differentiation of intraepithelial lymphocytes (IEL) are not fully understood. The present study therefore used intravital microscopy to investigate the migration of IEL to the villus mucosa and Peyer's patches of the small intestine. IEL were separated from inverted murine small intestine and mesenteric lymph node (MLN) T cells were also isolated. The adhesion of fluorescence-labeled lymphocytes to postcapillary venules (PCV) of Peyer's patches and arcade microvessels of small intestinal villi was observed after injection. In some experiments, the effect of antibodies against adhesion molecules on cell kinetics were investigated. IEL time-dependently accumulated in villus microvessels of the small intestine, whereas few MLN cells did. Few IEL adhered to the PCV of Peyer's patches. IEL were shown to express α_Eβ₇-integrin but not L-selectin. The accumulation of IEL in villus archade was significantly inhibited by antibody against β₇-integrin or mucosal addressin cell adhesion molecules (MAdCAM)-1, but not by α_E-integrin. The combined blocking of β₇-integrin and MAdCAM-1 further attenuated the sticking of IEL in this area, although it did not entirely block the IEL adherence. The adherence of CD4⁺ or TCRαβ IEL to villus microvessels was significantly greater than that of CD4^- or TCRγδ IEL. It was demonstrated in situ for the first time that IEL adhered selectively to the villus microvessels of the small intestine partly via β₇ and MAdCAM-1.

The recirculation of lymphocytes through the intestinal mucosa is important for specific immune defense, but the origin and differentiation of intraepithelial lymphocytes (IEL) are not fully understood. The present study therefore used intravital microscopy to investigate the migration of IEL to the villus mucosa and Peyer's patches of the small intestine. IEL were separated from inverted murine small intestine and mesenteric lymph node (MLN) T cells were also isolated. The adhesion of fluorescence-labeled lymphocytes to postcapillary venules (PCV) of Peyer's patches and arcade microvessels of small intestinal villi was observed after injection. In some experiments, the effect of antibodies against adhesion molecules on cell kinetics were investigated. IEL time-dependently accumulated in villus microvessels of the small intestine, whereas few MLN cells did. Few IEL adhered to the PCV of Peyer's patches. IEL were shown to express alpha(E)beta(7)-integrin but not L-selectin. The accumulation of IEL in villus archade was significantly inhibited by antibody against beta(7)-integrin or mucosal addressin cell adhesion molecules (MAdCAM)-1, but not by alpha(E)-integrin. The combined blocking of beta(7)-integrin and MAdCAM-1 further attenuated the sticking of IEL in this area, although it did not entirely block the IEL adherence. The adherence of CD4(+) or TCRalphabeta IEL to villus microvessels was significantly greater than that of CD4(-) or TCRgammadelta IEL. It was demonstrated in situ for the first time that IEL adhered selectively to the villus microvessels of the small intestine partly via beta(7) and MAdCAM-1.

In an effort to clarify the etiology of milk allergy from the standpoint of allergen-specific immune reactions, we investigated the determinants of IgE, IgG4, and T cells specific for bovine @a"s"1-casein from the same individual patients by using its synthetic peptides and cyanogen bromide-digested fragments. @a"s"1-Casein is a major allergen in cow's milk, and its unique conformation enabled us to investigate the determinants of antibodies without consideration about missing the reactivities because of conformational changes. Nine patients were selected as subjects from among 129 milk-sensitive infants screened by ELISA to assess the anti-@a"s"1-casein IgE levels in their sera. By using ELISA for epitope mapping, a C-terminal region of @a"s"1-casein was identified as a common binding site for IgE from all of these patients, whereas those for anti-@a"s"1-casein IgG4 were located in multiple regions of @a"s"1-casein. We determined the specificities of seven @a"s"1-casein-specific T-cell lines established from peripheral blood mononuclear cells of two of the patients. These T cells have been shown to secrete IL-4. All of the T-cell lines had different specificities to @a"s"1-casein. However, a common amino acid residue use was found among the determinants of various T-cell lines from each patient. The results suggest that patients allergic to cow's milk have characteristic B cells recognizing a limited region of @a"s"1-casein and secreting @a"s"1-casein-specific IgE. These B cells may interact particularly with T cells recognizing determinants with a common structure. (J Allergy Clin Immunol 1998;101:660-71)