Second Job: Activating Immune Responses
When a cell is cancerous or infected by a pathogen, it generates proteins not found in normal cells. Fragments of such proteins can then potentially act as antigens, substances that provoke an immune response. But immune cells must first be made aware of the problem. Heat shock proteins,
primarily members of the HSP90 and HSP70 families, participate in sounding the alarm and identifying the culprits.
1. HSP delivers antigens from diseased cells to the immune system’s antigen-presenting cells (APCs), via a surface receptor known as CD91.
2. After internalizing the antigen, the APC releases inflammatory signals to recruit other immune cells and presents the antigen on its surface to a T cell.
3. Thus primed to recognize the target antigen, the T cell proliferates and with its brethren seeks out diseased cells to destroy.