Tag: immunity and the lines of immunity

Toxoid is a type of vaccines obtained from the toxin and are inactivated and made harmless by chemical or heat treatment. Eg- tetanus toxoid is obtained by Clostridium tetani. These vaccines provide artificial active acquired immunity. So, the correct answer is 'Artificial active acquired immunity'.

Short-lived immunity acquired from mothers to foetus across placenta or through mother's milk to the infant is categorized as passive immunity. In passive immunity there is transfer of preformed antibodies in host to a recipient. In this case, the resistance is passively transferred from the mother to the foetus through placenta or through mother's milk. So, the correct answer is 'Passive immunity'.

Passive immunity is the transfer of active humoral immunity in the form of ready-made antibodies, from one individual to another. Passive immunity can occur naturally when maternal antibodies are transferred to the fetus through the placenta and can also be induced artificially when high levels of human (or horse) antibodies specific for a pathogen or toxin are transferred to non-immune individuals. Passive immunization is used when there is a high risk of infection and insufficient time for the body to develop its own immune response, or to reduce the symptoms of ongoing or immunosuppressive diseases.

Live, attenuated vaccines contain a living microbe that has been weakened in the lab so it cannot cause disease. Because a live, attenuated vaccine is the closest thing to a natural infection, these vaccines elicit strong cellular and antibody responses and often confer lifelong immunity with only one or two doses. Vaccines against measles, mumps, and chickenpox, for example, are made by this method. 

A vaccine is the killed or live suspension of microorganism which helps to activate the immune response. The agent stimulates the body's immune system to recognize the agent as a threat, destroy it and keep a record of it so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters.

Innate immunity refers to non-specific defense mechanisms that are present in the human body by birth to protect against the antigen. These mechanisms include physical barriers such as skin, chemicals in the blood and immune system cells that attack foreign cells in the body.

Answer is option A i.e. "Direct cell membrane- to- membrane contact"
Antigen-presenting cells (APC) are immune system cells that present antigens on the cell surface which then communicate with appropriate T cell receptors by membrane-to-membrane contact. Antigen-presenting cells are involved in both the innate and adaptive immune responses.

The natural way of destroying the bacterial infection is the production of the antibodies by the plasma B-cells in the body. The production of HCl also kills the harmful bacteria. The WBCs are the cells which can phagocyte and destroy the bacterial cells.