CD28 costimulatory signals in T lymphocyte activation: Emerging functions beyond a qualitative and quantitative support to TCR signalling

Optimal T cell response to antigen is achieved following the recognition of peptide-major histocompatibility complex (MHC) by TCR (signal one) together with a subset of co-stimuli (signal two), generally provided by counter-receptors expressed on the surface of APCs. Since its discovery in early 1980s, CD28 has been considered the most prominent co-stimulatory molecule for optimal T cell clonal expansion, differentiation and effector functions. CD28 is a 44kDa glycosylated, disulfide-linked homodimeric type I transmembrane protein expressed on the surface of 80% of human CD4+ T cells, 50% of human CD8+ T cells [1] and 100% of both murine CD4+ and CD8+ T cells [2].
Source: Cytokine and Growth Factor Reviews - Category: Molecular Biology Authors: Tags: Mini review Source Type: research