CD4 cells , also known as T-helper cells, are a type of white blood cell that plays a crucial role in the immune system. These cells are responsible for recognizing and interacting with foreign substances such as viruses, bacteria, and other pathogens, and coordinating the immune response to these invaders. CD4 cells are named after the CD4 protein that is present on their surface. This protein helps the cells recognize and bind to other immune cells, such as antigen-presenting cells, which present the pathogen to the CD4 cell for recognition. Once activated, CD4 cells release chemicals known as cytokines, which stimulate the immune response and help other immune cells, such as CD8 cells and B cells, to mount an attack against the pathogen. This coordinated response is critical for the body to successfully fight off infections. Unfortunately, certain diseases, such as HIV, can specifically target and destroy CD4 cells, leading to a weakened immune system and an increased suscepti...