There are different types of immune cells in the body carrying out different roles.
The cells of immune system attack the disease causing agents and prevent infections.
They also kills the foreign microorganisms and destroy foreign proteins including snake poison.
Some of the cells are involved in neutralization of foreign material while others eat and destroy the disease-causing microbes.
While some of them help to keep a memory of the previous attack so as to launch a quick attack in-case of subsequent infection.This principle is exploited in preparation of vaccines.
Types of immune cells
The cells of the immune system are white blood cells. These white blood cells are of five types, and all of them have a role in the immune system.
- Monocytes and macrophages
The lymphocytes are the master cells of the immune system. They are differentiated into three sub-cells as
a) B lymphocytes
b) T lymphocytes and
c) Natural killer cells.
The cells play an essential role in the humoral immunity of the body. They produce immune defenses by releasing the antibodies. The circulating B cells comprise about 10-15% of total lymphocytes count. On getting in contact with the antigen, the B-cells are activated, proliferate and transform into from into plasma cells.
Depending on the maturation stage of B cells
B cells posses CD markers includes CD 19,20,21,23.
These cells are implicated by cell-mediated and delayed hypersensitivity.
T cells circulating comprise about 75-80% of lymphocytes.
T cells markers includeCD2, CD3, and CD4
The T cells are mainly divided into two sub-types
T helper cells
T suppressor cells
It is abbreviated as TH cells.These cells also promote and enhance antigen reaction of also termed as T regulatory cells
T he T Helper cells further divided into two sub-types
TH 1 cells elaborated IL-2, interferon (IFN) γ
TH 2 cells elaborated IL-4, IL-5, IL-6 and IL-10.
T suppressor cells
It is abbreviated as TS cells. They suppress the immune reaction, and cytotoxic destroy the invading antigen.hence are called cytotoxic T lymphocytes. CD8 cells are mainly involved in the destroyed by cell-mediated immune system and infections, viruses, tumor cells.
Natural killer cells
These cells comprise about 10-15% of circulating lymphocytes. The cells do not have B or T cells markers. The natural killer cells are part of the natural or innate immunity. These cells recognize antibody-coated target cells and bring about the killing of the target directly. This mechanism is mainly operative involved in viruses and tumor cells.
Monocytes and macrophages:
The role of macrophages in inflammation consisting of circulating monocytes and organ-specific macrophages. They remain in circulation for about three days before they enter tissues to become macrophages. The macrophages sub-population like dendritic cells found in the lymphoid tissue and Langerhans cells. The important immune function macrophages are as follows.
- Antigen recognition
- Secretory function
- Antigen presentation.
Neutrophils: These are granulocytic white blood cells. They are very high in some all the W.B.C combined. They are an important component of the innate immunity. They are highly phagocytic and they attack and engulf any microorganism present in the bloodstream. Once the microbe is engulfed, it destroyed by the release of lysosomal enzymes. During an infection, they are the first to react and move towards the point of inflammation.
Eosinophils: These cells are also called as acidophils. They combat parasitic infection predominantly than the microbial infections.
Basophils: These cells are also involved in immune reactions. They can perform phagocytosis, release histamine and serotonin. They are found in large number where there is an ectoparasitic infection due to ticks. They are very low in concentration in comparison to other white blood cells.