Question

Immunity in our body is of two types: Innate immunity and  acquired immunity. Innate immunity is a non-specific defence mechanism, whereas acquired immunity is pathogen-specific; it is called specific immunity too. Acquired immunity is characterised by memory. Antibodies are specific to antigens and there are different types of antibodies produced in our body: they are IgA, IgE, IgG and IgM. It shows primary response when it encounters the pathogen for the first time and secondary response during the subsequent encounters with the same Antigen/Pathogen.

1. Name the two types of specialised cells which carry out the primary and secondary immune response.
2. Why is the antibody-mediated immunity also called as humoral immune response?
3. The organ transplants are often rejected if not taken from suitable compatible persons.
   1. Mention the characteristic of our immune system that is responsible for the graft rejection.
   2. Name the type of immune response and the cell involved in it.
      OR
4. How is active immunity different from passive immunity?

Answer 1

1. B cells (B-lymphocytes) and T lymphocytes are the cells in charge of the primary and secondary immune response.
   B lymphocytes are activated when the body first comes into contact with a pathogen. B-cell activation is facilitated by T cells. Following activation, B cells differentiate into plasma cells, which subsequently differentiate into memory B cells and antibodies. The primary immune response is mounted by the short-lived antibodies. Because memory B cells were produced during the first contact, the immune system reacts more rapidly and efficiently to the same virus when it is encountered again. We refer to this as the secondary immune response.
2. In order to defend against pathogens that enter bodily fluids like lymph and blood plasma, the antibody-mediated immune system releases antibodies into these fluids. Thus, it is often referred to as the ‘humoral immune system.’
   In the bodily fluids, these antibodies combat the infection. B-lymphocytes produce plasma cells, which in turn produce antibodies.
3. 
   
   1. The immune system’s capacity to discriminate between “self” and “non-self” tissue is the feature that causes transplant rejection.
   2. Graft rejection is caused by a cell-mediated immune response that attacks the transplanted organ and is mainly composed of cytotoxic T-cells.
      OR
4. While passive immunity includes obtaining pre-made antibodies from an outside source, which provides instant but transient protection, active immunity is created when your body’s immune system makes antibodies in response to a pathogen or vaccination, providing long-lasting protection.