CD44 & CD28

CD28 is a co-stimulatory receptor found on T cells that plays a key role in T-cell activation and survival. It is a transmembrane protein expressed on naïve and activated T cells, binding to B7-1 (CD80) and B7-2 (CD86) on antigen-presenting cells (APCs). This interaction provides the necessary secondary signal for full T-cell activation, alongside T-cell receptor (TCR) engagement with antigen-presenting major histocompatibility complex (MHC). CD28 signaling promotes cytokine production, T-cell proliferation, and survival. In the absence of CD28 signaling, T cells may become anergic (non-responsive). Because of its role in immune regulation, CD28 is a target for therapeutic interventions in autoimmune diseases, transplantation, and cancer immunotherapy.

CD44 encodes a cell surface glycoprotein involved in cell-cell interactions, adhesion, and migration. It acts as a receptor for hyaluronan, influencing cell proliferation, differentiation, and survival. CD44 is expressed in various cell types, including immune cells, and is implicated in processes such as inflammation, wound healing, and cancer metastasis. It is also involved in immune cell trafficking, particularly during inflammatory responses.