Immune Network 2016;16(6):322-329

 

Unusual CD4+CD28– T Cells and Their Pathogenic Role

in Chronic Inflammatory Disorders

Ga Hye Lee and Won-Woo Lee

 

Abstract

CD28 is a primary co-stimulatory receptor that is essential for successful T cell activation, proliferation, and survival. While ubiquitously expressed on naive T cells, the level of CD28 expression on memory T cells is largely dependent on the T-cell differentiation stage in humans. Expansion of circulating T cells lacking CD28 was originally considered a hallmark of age-associated immunological changes in humans, with a progressive loss of CD28 following replicative senescence with advancing age. However, an increasing body of evidence has revealed that there is a significant age-inappropriate expansion of CD4+CD28– T cells in patients with a variety of chronic inflammatory diseases, suggesting that these cells play a role in their pathogenesis. In fact, expanded CD4+CD28– T cells can produce large amounts of proinflammatory cytokines such as IFN-γ and TNF-α and also have cytotoxic potential, which may cause tissue damage and development of pathogenesis in many inflammatory disorders. Here we review the characteristics of CD4+CD28– T cells as well as the recent advances highlighting the contribution of these cells to several disease conditions.



Keywords: CD28, Co-stimulatory receptor, CD4+CD28– T cells, Chronic inflammatory diseases, Cytotoxic potential