The cells of immune system

The cells of immune system

Main cells involved in this system are lymphocytes and macrophages (Mcp), lymphocytes are of 2 types :

• B-lymphocytes (B-cell) : mature in bone marrow
• T-lymphocytes (T-cell) : mature in thymus gland

T-Cells which remain in circulation are of different types :

• T_D (T delayed action) : plays active role in longer span of time.
• T_C (T cytotoxic cell or killer T cell) : secretes toxins to kill the pathogen.
• T_H (T helper cell) : helps other cells to participate in immune response. It is the major cell type constituting > 40% of the total.
• T_S (T suppressor cell) : suppresses the autoimmunity.

Memory cells :

Both B and T cell form memory cells with specific antibodies at its surface or with transformed gene which normally stay out of circulation and stored in spleen when the same antigen (or pathogen) enters the body these cells come into action, start producing effector cells. The macrophages (histiocytes, neutrophils and monocytes) help in identifying the epitope. They also secrete interferons.

Immunogenic balance

Ratio of different cell types of immune system is always maintained at definite level. Any change in it causes immunological imbalance and the failure of immunity. (e.g. AIDS virus kills TH cells).