Question

Immunity in our body is of two types (i) Innate immunity, and (ii) Acquired immunity. Innate immunity is a non-specific defence mechanism, whereas Acquired immunity is pathogen specific. Acquired immunity is characterised by memory. Antibodies are specific to antigens and there are four types of antibodies produced in our body - IgA, IgE, IgG and IgM. It shows primary response where it encounters the pathogen for the first time and secondary response during the subsequent encounters with the same antigen/pathogen. These immune responses are carried out with the help of two special types of lymphocytes present in the blood.

Name the two types of specialised cells which carry out the primary and secondary responses.

Hint:

Two lymphocytes of blood give acquired immunity.

Answer 1

Step 1: Recall:
Acquired immunity is carried out by two special lymphocytes found in the blood.

Step 2: The two cells:
The B-lymphocytes (B-cells) make antibodies into the blood. This is humoral immunity.
The T-lymphocytes (T-cells) do not make antibodies but help B-cells and attack infected cells. This is cell-mediated immunity.

Step 3: Link with the responses:
Both cell types respond the first time a pathogen enters (primary response). On later contact they give a faster and stronger secondary response, because memory cells remain.

Final Answer:
B-lymphocytes and T-lymphocytes.