INNATE AND ADAPTIVE IMMUNITY

INNATE IMMUNITY: Refers to non-specific defense mechanisms that come into play immediately or within hours of an antigen’s appearance in the body. These mechanisms include physical barriers such as skin, chemicals in the blood and immune cells that attack foreign cells in the body.

ADAPTIVE IMMUNITY

Also referred as the acquired immune system, is a subsystem of the immune system that is composed of specialized, systematic cells and processes that eliminates pathogens by preventing their growth.

WAYS OF ACQUIRING IMMUNITY

1. From mother to child through the placenta

2. From mother to child through breastfeeding

3. By having a clinical disease

4. By having a sub – clinical infection i.e. through the administration of vaccines.

5. Through the administration of toxoids e.g. tetanus toxoids (TT)

6. Through the administration of serum with antibodies like anti-tetanus serum, anti – snake venom, and anti – rabies etc.

IMMUNTY: Means a highly developed state of resistance against infectious diseases. It occurs when there are sufficient antibodies within the body to prevent the successful invasion and virulence of a particular micro - organism.

Immunity can be acquired in two ways i.e. naturally and or artificially and both forms may be active or passive in nature.

NATURAL IMMUNITY

In this form or type of immunity, the body manufactures its own antibodies to fight infections. Natural immunity is of two type i.e. natural active acquired immunity and natural passive acquired immunity.

i. NATURALLY ACTIVE ACQUIRED IMMUNITY​

In this form of immunity, the body manufactures antibodies following recovery from previous infection resulting from exposure of the body to specific infectious agent which is not sufficient enough to cause the particular infection/disease, but, can stimulate the production of antibodies within the body.

This form of immunity last longer and stands to provide future protection against the specific infections.

ii. NATURALLY PASSIVE ACQUIRED IMMUNITY

This is the form of immunity in which for instance a child gets immunity from his mother through transplacental transmission. The immunity does not last for a long period of time.

A. ARTIFICIAL IMMUNITY

In this type of immunity, the resistance occurs as a result of response to the administration of drugs introduced into the body to fight the infection. Artificial immunity is of two type i.e. artificial active acquired immunity and artificial passive acquired immunity

i. ARTIFICIALLY ACTIVE ACQUIRED IMMUNITY

This form of immunity develops in response to the administration of killed, attenuated vaccines, or toxoids. It is of great importance because the body plays very important role in the production of antibodies. It usually last long and may also last for life as in the case of active immunity induced by measles.

ii. ARTIFICIALLY PASSIVE ACQUIRED IMMUNITY

In this form of immunity, the individual plays no part in the production of antibodies; only readymade antibodies from the human or animal serums such as ATS, anti – tetanus are injected into the body to fight against the invading micro – organism without delay. The immunity is short lasting.

DEFINE ANTIGEN AND ANTIBODIES AND THEIR REACTIONS

ANTIGEN: This is any substance (vaccine serum) which when introduced into the body’s system under favorable condition can stimulate the production of antibodies.

ANTIBODIES: This is a specific form of blood protein produced in the lymphoid tissue and able to counteract the effects of bacterial antigens or toxins.

VACCINE: - is defined as the causative agent of a disease so modified that is incapable of producing disease while retaining its power to cause antibodies formation.

A vaccine is an all – immunizing preparation of living or dead organism or materials derived from organism.

Drawing from the above definition, it can be inferred that vaccine is an immunizing agent that when introduced into the body to illicit the production of antibodies or which provides ready – made antibodies against specific infectious disease.

Types of vaccine

1. Live vaccines

2. Inactivated vaccines

3. Toxoids

THE LIVE VACCINES: These are made from living organisms and of two:

a. Organism that causes the disease and whose virulence has been made weak by attenuation e.g. OPV.

b. Organisms of species which are related to the causative agent but which are naturally less virulent e.g. small pox vaccines.