Review of Immunity

Definition of immunity

The definition of immunity is "the capacity of the body to recognize, eliminate, and destroy antigenic material foreign to itself."

Categories of immunity

• Natural immunity: Natural immunity is something that both humans and animals have from birth or that they acquire over the course of development due to their species, racial makeup, or other unique characteristics. The natural defense against disease arises prior to coming into contact with an antigen. It is separated into three categories:
  • Species immunity: Certain species develop immunity against specific diseases, such as dogs, rats, and mice against tuberculosis and hens against tetanus.
  • Racial immunity: Due to their genetic makeup, certain persons have specific immunity. Because of this, yellow fever does not affect black people as frequently.
  • Individual quirks: During an epidemic, we frequently observe that not everyone who is exposed to the infection contracts the illness. Those who experience it may suffer more severely than others; all of these variations are caused by individual differences. to a particular
• Acquired immunity: Acquired immunity can be acquired by two ways:
  • Passive immunity: When antibodies produced in one body are transferred to another, a person can develop passive immunity. There are two types of passive immunity:
    • Natural passive immunity: The placenta allows maternal antibodies to reach the fetus. The infant is only protected by these antibodies against some diseases like tetanus, chickenpox, diphtheria, measles, etc. for a short period of time (between three and six months). The mother's level of immunity is a determining factor in this transplacental transfer. No antibodies for that specific disease will cross the placenta to the fetus if the mother lacks immunity to these illnesses. Therefore, it is preferable to immunize because, when a child is fully protected against the seven target diseases, her own child will eventually have immunity as well when she becomes a mother.
    • Artificial passive immunity: When injected into a suspect animal, a serum containing particular antibodies confers immunity. Passive immunization has been used for curative and preventative purposes. This immunity is of short duration and is particularly valuable in treatment when antibodies are missing in the patient's blood following an accident, an injury, or illnesses like diphtheria and tetanus.
      Antiserum is an immune serum fluid prepared to give against certain diseases. It is of three types:
      • Antibacterial serum has the ability to phagocytose, agglutinate, or destroy the bacterial cell. These sera are anti-plague, anti-meningococcal, and anti-streptococcal.
      • Antitoxic serum: It has the ability to counteract the organism's poisons. These anti-diphtheria and anti-tetanic sera are administered to the patient (as a treatment) to serve as a passive immunization.
      • Convalescent serum, also known as antiviral serum, is the serum of patients who have recovered from a particular illness (such as measles and poliomyelitis). It contains particular antibodies against the virus. These sera have been used to passively immunize patients with poliomyelitis and the measles. These convalescent sera don't contain any foreign proteins, thus they don't trigger serum reactions, but they could give the patient homologous serum jaundice (serum hepatitis).
• Active immunity: An individual's immune system becomes active when it comes into contact with pathogenic organisms or their byproducts. To combat the infections, the body is encouraged to manufacture its own antibodies. Once antibodies have been produced against the majority of diseases, a person is generally immune to subsequent infections for extended periods of time or even forever. Examples of diseases or immunizations that provide this protection include BCG, Polio, DPT, Measles, etc.
  Active immunity is of two types:
  • Natural active immunity: acquired through disease exposure (e.g., measles, chickenpox, etc.) or infection (e.g., poliomyelitis).
  • Artificial active immunity: This type of immunity can be obtained by administering vaccines containing microorganisms, their toxoid, or a combination of the two.