Learn about your child's immune system

POSITIVE PARENTING
By Assoc Prof Dr AMIR HAMZAH ABDUL LATIFF

When your child is sick, sometimes it may take days or weeks for him to recover. This depends on his immune system. Learn more about the ‘warriors’ in your child that combat infections.

THERE are tiny invaders thriving in our environment. Though not visible through the naked eye, they are everywhere – from the surfaces that we touch, to the air we breathe, and the food that we eat. These invaders, generically known as germs (viruses, bacteria, microbes, and parasites), look for every opportunity to invade the body and reproduce, as the body is an ideal environment for the propagation of these germs. When germs manage to get inside the body, they cause infections.

Thankfully, the body is actually able to protect itself through the body’s defense system. Made up of an intricate network of cells, tissues, and organs, the immune system offers an amazing protection mechanism that fends off the invasion by organisms outside the body.

During the early years of life, a child is most curious about the world – touching and feeling anything that he comes in contact with – which also makes him more susceptible to picking up various germs. Read on to find out how the immune system offers your child protection round the clock.

First line of defence

Your child has generally has three types of immunity, the first being innate immunity. Also known as non-specific immunity, this first line of defence against foreign invaders are inherent in each individual. They provide general protection and respond immediately against any possible threats to the body. This includes the external barriers of the body, such as:

·Skin. This is the primary physical barrier between germs and the body. Skin is tough and generally impermeable to bacteria and viruses. Additionally, the skin also secretes antibacterial substances, mildly antiseptic sweat and sebum that prevents entry and kills germs.

·Respiratory tract. Being the main entry source of airborne pathogens, the respiratory tract is lined with mucous. Pathogens that are not killed immediately are trapped in the mucous and moved to the throat by tiny hairs called cilia.

·Stomach. The hydrochloric acid produced and stored in the stomach will kill most invading organisms that reach this organ.

·Intestines. Intestines are also lined with mucous, which serves to protect the intestines from digestive chemicals and harmful organisms. Additionally, mucous also contains an enzyme, lysozome, that breaks down the cell wall of many bacteria.

·Cellular defences. If an invader slips through the barriers above, the immune system reacts by producing white blood cells, other chemicals, and proteins to attack and destroy the pathogens. The invaders are sought out and destroyed before they can reproduce.

Second line reinforcements

The second form of immunity is called acquired (or specific) immunity. It protects against pathogens that manage to survive the first line of defence. Unlike innate immunity, it is not present at birth and takes time to develop.

Through encounters with foreign substances, acquired immunity learns the best way to attack each pathogen, eliminate them from the body and develops a memory for that pathogen. In the event of a subsequent attack, the immune system will be able to respond more rapidly and effectively, providing better protection.

Generally, the most important components of acquired immunity are:

·Lymphocytes are a type of white blood cell that circulate in the blood stream. When antigens are detected, several types of cells work together to recognise and eliminate them. This occurs a few days after exposure of a foreign microorganism. The main types are T-cells and B-cells.

·Antibodies are proteins produced by B cells by binding to the antigens. By doing so, they protect the body by helping cells ingest antigens, inactivating toxic substances produced by bacteria, and directly attacking bacteria and viruses and activating the complement system.

·Memory T and B cells. After an encounter with a foreign microorganism, some lymphocytes develop into memory cells. When these cells encounter the same microorganism for the second time, they recognise it immediately and respond quickly. These cells live for a long time – extending from years to decades.

Passive defence

The third type of immunity that your child may obtain is passive immunity. Passive immunity refers to the protection that is adopted from another source and it is typically short-lived. For instance, antibodies in a mother’s breast milk provides baby with temporary immunity to illnesses the mother has been exposed to. This helps protect the baby against infection during the early stages of life.

The immune system works in concert with every system in the body. When it works, your child will be able to develop to his maximum potential, but when it malfunctions, terrible things will happen. Understanding your child’s immune system is crucial, as it can provide good indication of your child’s well-being and also guide you to help you maintain your child’s immune system at its optimal best.

Assoc Prof Dr Amir Hamzah Abdul Latiff is a paediatric immunologist and president of the Malaysian Society of Allergy and Immunology. This article is courtesy of the Malaysian Paediatric Association for the Positive Parenting Programme. For further information, please visit .