Hello, immunity is the state of having sufficient biological defenses to avoid infection, diseases or other unwanted biological invasion. It is the capability of the body to resist harmful microbes from entering it. It involves both specific and non-specific components. Inate or non-specific immunity is the defense system that you are born with. It protects you against all antigens. These barriers form the first line of defenses in the immune response, which includes cough reflex, enzymes in tears and skin oils, mucus which trap bacteria, skin, stomach acid. Inate immunity also comes in a protein chemical form, called innate humoral immunity that includes body s complement system and substances called interferon and interleukin. Acquired immunity develops with exposure to various antigens. Your immune system builds a defense against that specific antigen. Passive immunity is due to antibodies that are produced in a body other than your own. Infants have passive immunity because they are born with antibodies that are transferred to the placenta from the mother. These antibodies disappear between age of 6 and 12 months. Passive immunization may also be due to injection of antiserum, which contains antibodies that are formed by another person or animal. It provides immediate protection against an antigen, but does not provide long lasting protection. Immune serum globulin given for hepatitis exposure and tetanus antitoxin is examples of passive immunization.

The immune system includes certain types of white blood cells. It includes chemical and proteins in the blood, such as antibodies, complement proteins and interferon. Lymphocytes are a type of white blood cells. There are B and T type of lymphocytes’ lymphocytes become cells that produce antibodies. Antibodies attach to a specific antigen and make it easier for the immune cells to destroy the antigen lymphocytes attack antigens directly and help control the immune response. They also release chemical known as cytokines, which control the entire immune response. As lymphocytes develop, they normally learn to tell the difference between you and body tissues and substances that are not normally found in your body. Once B and T cells are formed, a few of those cells will multiply and provide memory for your immune system. This allows your immune system to respond faster and more efficiently the next time you are exposed to the same antigen. In many cases, it will prevent you from getting sick. For example, a person who has had chickenpox or has been immunized against chicken pox is immune from getting chicken pox again. The inflammatory response occurs when bacteria, trauma, toxins, heat or any other cause injures tissues. The damage cells release chemicals including histamine, bradykinin and prostaglandins. These chemicals cause blood vessels to leak fluid into the tissues causing swelling. This helps isolate the foreign substances from further contact with the body tissues. The chemicals also attract white blood cells called phagocytes that eat germ s and dead or damaged cells. This process is called phagocytosis. Phagocytes eventually die. Pus is formed from a collection of dead tissue, dead bacteria and live and dead phagocytes. Immunization is a way to trigger the immune response. Small doses of antigen, either dead or weakened live viruses are given to activate immune system, which allows your body to react quickly, and efficiently to further exposures. Complications seen due to an altered immune response includes allergy or hypersensitivity, Anaphylaxis. Graft versus host disease, serum sickness, transplants rejection, immune deficiency disorders and autoimmune disorders. An inefficient immune response allows disease to develop. An over active immune response can lead to the development of auto immune disease, in which antibodies form against the body s own tissues. So an efficient immune response protects against many diseases and disorders.

It would be best if you would consult your immunologist or pediatrician regarding your nephew s condition. Hope this helps. Thank you.