Antibodies, Immunity and Infection
Common Health Issues

Antibodies, Immunity and Infection


Antibodies are natural substance that protects the body against a specific disease or infection. Antibodies are part of the body’s natural immunity system. They destroy harmful bacteria and counteract the poisons produced by disease germs.


A specific antibody is usually produced by the body in response to a particular foreign protein, such as bacteria, allergens or an organ transplanted from another person.


Certain types of antibodies never disappear from the body, thus providing lifelong immunity to some diseases. Two examples of such antibodies are those that protect against second attacks of measles and of mumps. 


Most vaccines work by stimulating the formation of antibodies against a particular disease.


Immunity: Natural Defense and Medical Technique

Immunity is the condition of being resistant to an infectious disease. 


The body’s ability to resist and overcome disease depends on immunity, a natural defensive mechanism that is due to the presence in the blood and lymph streams of substances called antibodies. These attack disease-causing invaders, and there is an antibody for each disease.


Someone who is immune to a particular disease has the correct antibody already in his system. If it is lacking, the body cells produce the necessary antibody when invaders attack. Once formed, a specific antibody can provide lifelong resistance against a particular invader.


Antigens, the foreign substances that invade the body, stimulate the production of antibodies. Some are manufactured by various white cells, such as plasma cells and lymphocytes. Other antibodies are derived from the protein gamma globulin present in the bloodstream.


Immunity to particular diseases can be deliberately built up before exposure to infection by using immunization. One method involves giving injections of dead or weakened strains of bacteria or viruses called vaccines.


These preparations are strong enough to help the body produce antibodies, but are too weak to cause a dangerous infection.


Another method is to give an injection of blood serum containing ready-made antibodies, either from another human being or from an animal.


Types of Immunity

There are several types of immunity and they are as follows:


Natural Immunity

The immunity with which a person is born is natural immunity. Human beings are naturally immune to many diseases that afflict animals—for instance, human beings cannot catch swine fever. Certain groups of people have greater immunity to some diseases than to others. For example, some people are less immune to tuberculosis than others


Active Immunity

This type of immunity is acquired in two ways: 

Acquired through disease

Active immunity results when someone produces his own antibodies against a disease, usually after he has recovered from an illness. The body can produce many antibodies, some of which—such as those against measles—remain effective for years.


Acquired through vaccine

Active immunity may be produced by using a vaccine, which consists of dead or weakened strains of disease-causing bacteria or viruses. When the vaccine is injected, it stimulates the body to produce antibodies which combat any infections. It may cause mild symptoms of the disease.


Passive Immunity

This type of immunity is also acquired in two ways:

Acquired from the mother

Immunity may be passed on to a child from his mother. It is acquired in the womb from the mother’s bloodstream, or through the colostrum, the watery fluid that flows from the mother’s breasts for two or three days after the child’s birth.


Acquired from another victim

Antibodies or antitoxins can be taken from the blood of someone who has had a disease, and given to another who is suffering from it. Alternatively, antibody formation can be stimulated in the blood of an animal, such as a horse. This kind of immunity is always short-lived.



Immunization is the process of producing immunity by injecting certain substances into the body. 


Immunity against typhoid is produced by injecting dead typhoid bacteria. Smallpox vaccine contains living viruses that have been subjected to a process that weakens them. Immunity against diphtheria, tetanus, and other diseases is produced by injecting a Toxoid, which is an altered form of the toxin produced by the disease germ.


All of these substances stimulate the body to produce disease-fighting antibodies. It may take several weeks following an injection for the body to build up effective immunity. In some cases, a series of injections must be given, or Booster Shots, must be repeated from time to time to maintain immunity.


In passive immunization, the injected substance is a serum or an antitoxin that already contains the disease-fighting antibodies.


Everyone should be immunized at an early age against diphtheria, whooping cough, tetanus, poliomyeltis and measles.



Infectious diseases are caused by viruses, bacteria, fungi, worms and other parasites, which enter the body through the skin, nose, mouth or other openings of the body. The body has various barriers against such invasions.

The various organs and systems that the body uses to fight infections are:


Adenoids and Tonsils

They are made of lymphoid tissue and are located at the entrances to the throat. They act as barriers to bacteria and viruses


Mucous Membrane

This is a soft moist tissue lining the body openings and passages, such as the nose and the throat. It secretes mucus, a sticky fluid that provides protection against some bacteria. In the nasal cavity, the mucous membrane also catches germs and dust


Lymph Nodes

They are small, lumpy structures scattered along the course of the lymphatic system. The neck, armpits and groin have the greatest numbers where they act as traps for bacteria and other invaders. The nodes also make white blood cells which attack foreign matter, and help to form antibodies



It produces two substances, fibrinogen and prothrombin, which make blood clot and so help wound-healing. This large organ also destroys many parasites and poisons which are carried to it in the bloodstream

Lymphatic System

This is a second circulation, which is intertwined with the network of blood vessels. The lymph stream contains white blood cells, which help to stop the spread of infection by producing antibodies


Lachrymal Glands

They are located above the outer corner of each eye. It secretes tears which wash dust and dirt from the eyes. Tears also contain lysozyme, a substance that combats bacteria


Salivary Glands

They are found in the cheeks and under the tongue. The saliva they secrete contains substances which help to resist infection


It has lymphoid tissue, helps to form white blood cells and remove used red ones



It has digestive juices including hydrochloric acid, which helps to sterilize the food intake



They contain bacteria which usually remain there and are harmless. Some intestinal bacteria, such as bacillus coli, cause disease if they get into other areas of the body


It provides the body’s main protection against diseases. Because it is dry and slightly acid, and its surface is constantly being replaced, invaders rarely colonize the skin, except in the case of injury. Beneficial bacteria live on the skin, but can be a cause of illness if they penetrate below the surface.



Most of the germs that penetrate the body are bacteria or viruses. These disrupt bodily functions and release poisons called toxins. Their effects are counteracted by the body’s defensive cells.

Some body cells produce antibodies, substances that counteract a particular invader. Each antibody is tailor-made to combat a particular antigen—which may be a protein on the surface of a bacterium, or a toxin produced by the infection.


After infection is past, the antibodies may remain in the bloodstream, giving immunity against similar invasions. 

Body cell attack disease-causing bacteria, or pathogens, in various ways. Some antibodies break up bacteria before destroying them. Others prevent their growth by causing them to clump together; the clumped bacteria are then mopped up by white blood cells. Certain antibodies are antitoxins, which neutralize bacterial poisons. 


Like bacteria, viruses stimulate the body cells to produce antibodies. In some diseases, such as smallpox, one infection produces long-term immunity. But in other cases, such as colds and influenza, the antibodies are effective only for a short time.


The process of the cells fighting infection goes as follows:

Start of Infection

It occurs when germ enter the body through a cut. White blood cells engulf them, but if the germs are not destroyed by these cells, they may enter the blood and lymph streams and multiply, causing generalized ‘blood poisoning.’



They are the first defensive white cells to arrive at the site of an infection. They are formed in the bone marrow and the spleen, they begin to engulf the bacteria, although their effectiveness against these infective invaders is short-lived



They are longer-living types of white blood cells, they move in after the neutrophils. These new arrivals turn into macrophages, cells that remove pathogens and disintegrating neutrophils. The macrophages also play a part in antibody formation



They are a third type of white blood cells which also enter infected areas. When these small cells come in contact with bacteria, they develop into larger cells. These new lymphocytes create plasma cells, which control antibody production



They are eventually engulfed by macrophages and lymphocytes, and are also attacked and destroyed by antibodies. These substances are produced by plasma cells in the lymphatic system, through which they travel to infected areas.


End of Infection

This occurs with the destruction of bacteria and the removal of debris. The bacterial antigens stimulate sensitive white cells to produce antibodies which provide immunity against later attacks by the same invaders.


Rich Health Editorial Team

Health Research

Rich Health Editorial Team is made up of medical practitioners and experienced writers who provide information for dealing with health issues in a simple and easy-to-understand manner