B2 [ U ] a situation in which people are peaceful and agree with each other, or when things seem right or suitable together: racial harmony (= good feelings between different races) domestic harmony (= good feelings in the family or home) Imagine a society in which everyone lived together in (perfect) harmony. We must ensure that tourism develops in harmony with the environment.
Once activated, helper T cells start to divide and to produce proteins that activate B and T cells as well as other immune cells. The killer T cell is specialized in attacking cells of the body infected by viruses and sometimes also by bacteria. It can also attack cancer cells. The killer T cell has receptors that are used to search each cell that it meets.
The main organs in the immune system are the bone marrow, thymus, spleen and lymph nodes. Let us have a look at these immune system organs and functions. Bone Marrow: All the cells of the human immune system are formed in the bone marrow, found within the bones, by a process called hematopoiesis.-Cells: The main function of T-cells or T lymphocytes is intensifying immune system responses. They do this by secreting specialized factors, which in turn activate other white blood cells, to fight off infections. T-cells are again subdivided into different types.