Cellular Immunity and Immune Responses

Cellular Response

Cellular response - Cell-mediated immunity is a form of adaptive immune response mediated by T lymphocytes. It acts as an attack mechanism against intracellular microorganisms, such as viruses and some bacteria, that can survive and proliferate inside phagocytes and other host cells. The defense against such infections depends on cellular immunity, which induces the destruction of the organism living in phagocytes or infected cells.

A phagocyte captures an element, becoming a macrophage. After several processes, helper T cells are created and activated, which perform cytotoxicity (lysis of target cells by cytotoxic T cells) and regulation of the immune response by T helper cells.

Primary and Secondary Immune Response

Primary and secondary immune response (immunological memory)

• Primary: There is a latent period in which the antigen is identified, and lymphocytes multiply. After several processes, the antibodies have a very low production level, almost imperceptible in blood.
• Secondary: This occurs when the antigen is detected again, producing a different response from the previous one, with a higher presence of IgG.

Types of Immunity

• Innate - Includes the cells and mechanisms that defend the host from infection by other organisms non-specifically. This means that cells respond to pathogens generically. The innate immune system provides immediate defense against infection. It is acquired from birth and is found in all animal and plant life. It can be specific to a race or individual.

• Acquired/Adaptive - Acquired immune response is specific to antibodies and requires recognition of non-self antigens in a process called antigen presentation. It is achieved throughout life through the formation of antibodies during infection. It is specific to the pathogen, with a highly variable duration. The mechanism is based on immunological memory and the artificial production of antibodies through medical techniques.

  • Natural Passive: Acquired by transferring antibodies from mother to baby through the placenta and breast milk.
  • Natural Active: The body's immune system makes antibodies after suffering an infection.
  • Artificial Active: Achieved through vaccines, a set of antigens introduced into the body to prevent and cure infection. Vaccines take several days to take effect, are sustainable, possess immunogenicity, and produce no side effects.
  • Artificial Passive: Consists of introducing neutralizing antibodies into the body so that the immune system need not be activated.