TAP-independent selection of CD8 super(+) intestinal intraepithelial lymphocytes

• Published in: The Journal of immunology (1950) Vol. 156; no. 11; pp. 4209 - 4216
• Main Authors: Sydora, B C, Brossay, L, Hagenbaugh, A, Kronenberg, M, Cheroutre, H
• Format: Journal Article
• Language: English
• Published: 01.01.1996
• ISSN: 0022-1767

Intestinal intraepithelial lymphocytes (IEL) are mostly CD8 single positive T cells. IEL with a TCR- alpha beta that are CD8 single positive are absent from beta sub(2)-microglobulin ( beta sub(2)m)-deficient mice, consistent with the idea that these IEL, like other TCR- alpha beta super(+),CD8 super(+) T cells, require class I molecules for positive selection. In contrast, here we show that substantial numbers of TCR- alpha beta super(+),CD8 single positive IEL are present in mice deficient for the transporter associated with Ag processing 1 (TAP 1) gene, although T cells with this phenotype are absent from thymus, spleen, and lymph nodes of these same mice. The majority of TCR- alpha beta super(+),CD8 single positive IEL in TAP-deficient mice expresses CD8 molecules composed of alpha alpha homodimers and they express a diverse set of V beta gene segments. In addition, the number of TCR- alpha beta super(+),CD4/CD8 double positive IEL is decreased in beta sub(2)m-deficient mice but not in TAP-deficient mice. The dependence of the two TCR- alpha beta super(+) IEL populations that express CD8 alpha alpha homodimers on beta sub(2)m as opposed to TAP molecules is striking. It suggests that TAP-independent but beta sub(2)m-requiring nonclassical class I molecules expressed by cells in the intestine, such as the thymus leukemia Ag and CD1, could play a pivotal role in the development and/or the accumulation of major subpopulations of TCR- alpha beta super(+) IEL.