T and IgA B lymphocytes of the pharyngeal and palatine tonsils: differential expression of adhesion molecules and chemokines.

The pharyngeal (Ph) and palatine (Pa) tonsils, although located in different regions of the upper aero-digestive tract (UADT), are thought to protect the respiratory tract similarly against infections by inducing and disseminating T and surface IgA(+) (sIgA(+)) B cells. We investigated the factors controlling the migratory properties of T and sIgA(+) B lymphocytes in the UADT of pigs by comparing the expression of vascular addressins, homing receptors and chemokine transcripts in Ph/Pa tonsils, Peyer's patches (PP) and their draining lymph nodes (LN). The vascular addressin PNAd was detected on high endothelial venules in both tonsils, whereas mucosal addressin cell adhesion molecule-1, otherwise present in PP and mesenteric LN, was not detected. More importantly, the vascular cell adhesion molecule-1 (VCAM-1) addressin was present in Ph tonsil and LN but neither in Pa tonsil nor in PP vascular cells, whereas both T and sIgA(+) B lymphocytes displayed similar levels of alpha4beta1(high) integrin, the ligand of VCAM-1. Analysis of transcript levels for several lymphoid (CCL19, CXCL12 and CCL21) and epithelial chemokines also demonstrated opposite chemokine mRNA ratios for Ph tonsil (CCL28 > CCL25) and PP, with Pa tonsil expressing very low levels of CCL28. Collectively, these data indicate that the differential compartmentalization of sIgA(+) lymphocytes between Pa and Ph tonsils may partly result from the differential expression of VCAM-1 and CCL28. They also suggest that tonsillar addressins and epithelial chemokines, rather than the cells intravasating it, control the regionalization of sIgA(+) lymphocytes in the UADT.

Relationships of microsporidian genera, with emphasis on the polysporous genera, revealed by sequences of the largest subunit of RNA polymerase II (RPB1).

Molecular data have proved useful as an alternative to morphological data in showing the relationships of genera within the phylum Microsporidia, but until now have been available only for ribosomal genes. In previous studies protein-coding genes of microsporidia have been used only to assess their position in the evolution of eukaryotes. For the first time we report on the use of a protein-coding gene, the A-G region of the largest subunit of RNA polymerase II (RPB1) from 14 mainly polysporous species, to generate an alternative phylogeny for microsporidia. Using the amino acid sequences, the genera and species fell into the same main groupings as had been obtained with 16S rDNA sequences, but the RPB1 data provided better resolution within these groups. The results supported the pairings of Trachipleistophora hominis with Vavraia culicis and Pleistophora hippoglossoideos with Pleistophora typicalis. They also confirmed that the genus Pleistophora is not monophyletic and that it will be necessary to transfer Pleistophora ovariae and Pleistophora mirandellae into one or more other genera, as has already been effected for Pleistophora anguillarum.