Question

In a cell-mediated immune response, T-lymphocytes divide and secrete
A) Antigens
B) Plasmogens
C) collagens
D) cytokines

Answer 1

Hint: Cell-mediated immunity is called so because its effectors were such cells that comprise the immune system. It is affected by T-cells, APCs, and target cells. It cannot be transferred without T-cells. When t-cells interact with antigen then it activates effector T-cells and Memory T-cells.


Complete step-by-step answer:
When TH cells are activated by 2 signals activated TH cell undergoes clonal expansion (very rapid cell division by mitosis ) and secret cytokines. Cytokines are cell-signaling molecules. These cytokines further activate the immune system and cause TH cells to be differentiated into effector and memory T cells. Activated TH cells secrete many types of cytokines.
Based on the set of cytokines being secreted are of two types:
1) TH 1 cells secrete IL-2, IFN, and TNF. These cells activate cell-mediated immunity mechanisms such as delayed-type hypersensitivity( DTH) and activation of Tc cells.
2) TH2 cells secete IL-4, IL-5 , IL-6 and IL-10. These cells activate B cells and enhance antibody production.
Collagen is the main structural protein in the extracellular matrix found in the body’s connective tissue. They are secreted by fibroblast cells.
Antigens are the substances that cause our immune system to produce antibodies against the pathogen.


Therefore the correct answer is Option D.

Note: Antibody molecules secreted from B cells, play a critical role in interacting with the antigens when they are present outside the cells; for example when viruses are encountered in blood plasma or at mucosal surfaces. Once an antigen gets into a cell, however, antibodies do not generally have access to it, so antibodies are ineffective in dealing with antigens present within the cells. T cells deal with pathogens- such as viruses, bacteria, and parasites- that reside inside the host.