Enhanced differentiation of intraepithelial lymphocytes in the intestine of polymeric immunoglobulin receptor-deficient mice.

To clarify the effect of secretory IgA (sIgA) deficiency on gut homeostasis, we examined intraepithelial lymphocytes (IELs) in the small intestine (SI) of polymeric immunoglobulin receptor-deficient (pIgR(-/-) ) mice. The pIgR(-/-) mice exhibited the accumulation of CD8αβ(+) T-cell receptor (TCR)-αβ(+) IELs (CD8αβ(+) αβ-IELs) after weaning, but no increase of CD8αβ(+) γδ-IELs was detected in pIgR(-/-) TCR-β(-/-) mice compared with pIgR(+/+) TCR-β(-/-) mice. When 5-bromo-2'-deoxyuridine (BrdU) was given for 14 days, the proportion of BrdU-labelled cells in SI-IELs was not different between pIgR(+/+) mice and pIgR(-/-) mice.

Essential roles of monocytes in stimulating human peripheral blood mononuclear cells with Lactobacillus casei to produce cytokines and augment natural killer cell activity.

We examined the effect of a probiotic strain, Lactobacillus casei strain Shirota, on cytokine production and natural killer (NK) cell activity in human peripheral blood mononuclear cells (PBMNC). The cellular mechanisms of immunoregulation by L. casei strain Shirota were also investigated.

Accumulation of intestinal intraepithelial lymphocytes in association with lack of polymeric immunoglobulin receptor.

Immunoglobulin A (IgA) is transported by the polymeric immunoglobulin receptor (pIgR) through epithelial cells of the gut, the airways, the tear and salivary glands, and the lactating mammary gland, and IgA accumulates in serum and the intestinal lamina propria of pIgR-deficient (pIgR(-/-)) mice. Intraepithelial lymphocytes (IEL) increased in number and Thy-1(+)CD8alphabeta(+)TCRalphabeta(+) IEL preferentially expanded in the small intestine (SI) of pIgR(-/-) mice. Cytotoxic activity of SI-IEL was comparable in pIgR(+/+) and pIgR(-/-) mice.

Protection against influenza virus infection in polymeric Ig receptor knockout mice immunized intranasally with adjuvant-combined vaccines.

The role of secretory IgA in conferring cross-protective immunity was examined in polymeric (p)IgR knockout (KO) mice immunized intranasally with different inactivated vaccines prepared from A/PR/8/34 (H1N1), A/Yamagata/120/86 (H1N1), A/Beijing/262/95 (H1N1), and B/Ibaraki/2/85 viruses and infected with the A/PR/8/34 virus in the upper respiratory tract (RT)-restricting volume. In wild-type mice, immunization with A/PR/8/34 or its variant (A/Yamagata/120/86 and A/Beijing/262/95) vaccines conferred complete protection or partial cross-protection against infection, while the B-type virus vaccine failed to provide protection. The protection or cross-protection was accompanied by an increase in the nasal A/PR/8/34 hemagglutinin-reactive IgA concentration, which was estimated to be >30 times the serum IgA concentration and much higher than the nasal IgG concentration.