Elevated production of interferon‐γ and interleukin 4 by mature T cells from autoimmune Ipr mice correlates with Pgp‐1 (CD44) expression

Authors:
  • JSJodi H. Schumacher
    Jodi H. Schumacher
  • TMTim R. Mosmann
    Tim R. Mosmann

Abstract
The cell surface glycoprotein, Pgp‐1 (CD44), has been shown to be a marker of murine memory T lymphocytes. When activated, Pgp‐1hi memory T cells produce strikingly higher amounts of interferon‐γ (IFN‐γ) than naive Pgp‐1lo T cells, yet both subsets make similar levels of interleukin (IL)2. Whereas Pgp‐1hi cells represent only 20%–25% of peripheral T cells from most strains, this marker is expressed by the vast majority (> 90%) of T cells from autoimmune MRL mice homozygous for the lymphoproliferation (lpr) gene. The massive lymphadenopathy that develops in lpr/lpr mice is composed of both non‐mature (CD4−CD8−) T cells as well as a greatly expanded number (up to 300‐fold) of mature (CD4+CD8−, CD4−CD8+) T cells. Paralleling the expression of high levels of Pgp‐1, we find that compared to normal mouse T cells, the lpr mature T lymphocyte subsets are also very high producers on a per cell basis of IFN‐γ and, for the CD4+ subset, IL4. Increased concentrations of IFN‐γ and IL4 produced by large numbers of lpr Pgp‐1hi mature T cells could contribute to the autoimmune syndrome in MRL lpr/lpr mice through the effects of these cytokines on augmenting MHC class II expression and production of certain classes of antibodies.

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