CD43 – One molecule, many tales to recount

Immune cells functions are regulated through the orchestrated intervention of immune receptors that recognize non-self peptides or pathogen associated molecular patterns and of molecules that modulate the signals these receptors generate. These molecules, known as accessory or co-receptor molecules, sense the environment, setting the threshold for cell activation, as well as instructing the cells to ensure self-tolerance and homeostasis. CD43 is an abundant cell surface protein, expressed on nearly all lineages of hematopoietic cells. Multiple, and sometimes opposite functions, have been attributed to CD43: adhesion and anti-adhesion, locomotion, cellular activation, differentiation, proliferation and apoptosis. Here we will summarize recent developments in our understanding of the role this molecule plays in different cell types. In particular, we will illustrate the role of CD43 as a T cell accessory molecule, capable of generating intracellular signals, independently of or in coordination with the TCR, actively modulating T cell response. In addition, we review new functions for this molecule, in non-immune cells.