The body is made up of different cells and each type of cell has important functions. In this article, we are going to discuss T cell and B cells; their roles and differences.
Picture 1: T cells are a component of lymphocytes.
Image Source: wikimedia.org
Picture 2: T cells helps fight off cancer cells.
Image Source: verywellhealth.com
What are T cells?
T cells are white blood cells vital to the immune system. They are like soldiers that identify and destroy invaders. They are called T cells because they mature in the thymus. T cells are also called T lymphocytes. (1, 2)
What are the types of T cells?
- Killer T cells – These T cells have x-ray vision. They can see the inside of the body’s own cells by scanning the surface. They can easily hunt and destroy infected cells.
- Helper T cells – These T cells assist in immune response.
- Suppressor T cells – These T cells block the actions of other types of lymphocytes.
What are the roles of T cells?
- They destroy infected/harmful cells.
- They scan the inner structure of foreign invaders.
- They help eradicate cancer cells.
- They have the ability to remember invaders they encountered a long time ago.
- They help other immune cells in detecting and ingesting harmful cells.
- They are responsible for immune response leading to rejection of transplanted organ, allergic reactions, autoimmune diseases such as rheumatoid arthritis and diabetes. (1, 2, 3, and 4)
Picture 3: A closer look at B cells, a component of lymphocyte.
Image Source: wikimedia.org
What are B cells?
B cells are white blood cells that protect the body from infection. They originate from the hematopoietic stem cells inside the spongy bone marrow. Once they mature, they travel to the blood and other parts of the body such as the lymph nodes. (5, 6)
What are the roles of B cells?
- They are involved in the body’s response to foreign invaders through humoral immunity.
- They signal other immune cells to destroy the invaders.
- Some activated B cells become memory cells and live in the bone marrow, spleen, and lymph nodes. They have the ability to remember antigens they encountered in the past. Hence, B cells give long-lasting immunity to various invaders.
- They ensure cell specificity.
- They regulate the construction of antigen receptors.
- They play a vital role in antibody production.
- They export all the needed cells in the periphery.
- They help in rearranging antigen receptors. (5, 6, and 7)
Picture 4: A comparison image between T cells and B cells.
Image Source: askabiologist.asu.edu
Difference between B cells and T cells
Originate
- T cells – They are lymphocytes that originate in the bone marrow and mature in the thymus.
- B cells – They are lymphocytes that originate and mature in the bone marrow.
Position
- T cells – They are positioned inside the lymph nodes.
- B cells – They are positioned outside the lymph nodes.
Where they recognize antigens
- T cells – They recognize antigens found outside of the infected cells.
- B cells – They recognize antigens found on the surface of antigens. (8, 9)
Membrane Receptor
- T cells – TCR receptor
- B cells – BCR receptor
Distribution
- T cells – They are distributed in the lymph nodes specifically in the parafollicular area of the cortex and the periarteriolar lymphoid sheath of the spleen.
- B cells – They are distributed in the germinal centers, subcapsular and medullary cords of the lymph nodes, gut, spleen, and respiratory tract. (8, 9)
Presence of surface antibodies
- T cells – They do not have surface antibodies.
- B cells – They have surface antibodies.
Life Span
- T cells – They have a long lifespan.
- B cells – They have a short lifespan.
Type of secretion
- T cells – They secrete lymphokines.
- B cells – They secrete antibodies. (9, 10)
Composition/proportion in the blood
- T cells – 80% of the blood lymphocyte is composed of T cells.
- B cells – 20% of the blood lymphocyte is composed of B cells.
Type of immunity
- T cells – Cell-mediated immunity.
- B cells – humoral/antibody-mediated immunity
Types
- T cells – There are three types: helper T cells, killer T cells, and suppressor T cells.
- B cells – There are two types: plasma cells and memory cells.
Response to the infected site
- T cells – They move right away to the infection site.
- B cells – They do not move to the infection site.
Reaction to transplant and tumor cells
- T cells – They act against the transplant and tumor cells.
- B cells – They do not act against transplant and tumor cells.
Inhibitory effect
- T cells – A particular type of T cell, specifically suppressor T cell has an inhibitory response to the immune system.
- B cells – They do not have an inhibitory response to the immune system. (8, 9, and 10)
What they fight against?
- T cells – They fight almost all pathogens which include but not limited to viruses, fungi, and protists that enter the body.
- B cells – They fight against viruses and bacteria in the lymph and bloodstream.
Refer to the table below for a detailed comparison between T cells and B cells.
|
Key differences | T cells | B cells |
| Originate | Originate in the bone marrow and mature in the thymus | Originate and mature in the bone marrow |
| Type |
|
|
| Position/location | inside the lymph nodes | outside the lymph nodes |
| Where they recognize antigen | Outside the infected cells | On the surface of antigen |
| Membrane receptor | TCR receptor | BCR receptor |
| Distribution | Parafollicular area of the cortex and the periarteriolar lymphoid sheath of the spleen | The germinal centers, subcapsular and medullary cords of the lymph nodes, gut, spleen, and respiratory tract |
| Lifespan | Longer | Shorter |
| Presence of surface antibodies | None | Present |
| Type of secretion | Lymphokines | Antibodies |
| Type of immunity | Cell-mediated immunity | humoral/antibody-mediated immunity |
| Proportion in the blood | 80% of blood lymphocyte | 20% of blood lymphocyte |
| Response to the infected site | Move right away to the infection site | Do not move to the infection site |
| Reaction to transplant and tumor cells | Act against the transplant and tumor cells | Do not act against transplant and tumor cells |
| Inhibitory effect | Some T cells inhibit the response to the immune system | Do not have the inhibitory response to the immune system |
| What they fight against |
| Viruses and bacteria in the lymph and bloodstream (8, 9, and 10) |
References
- https://en.wikipedia.org/wiki/T_cell
- https://www.medicinenet.com/script/main/art.asp?articlekey=11300
- https://www.immunology.org/public-information/bitesized-immunology/cells/helper-and-cytotoxic-t-cells
- https://askabiologist.asu.edu/t-cell
- https://en.wikipedia.org/wiki/B_cell
- https://www.immunology.org/public-information/bitesized-immunology/cells/b-cells
- https://www.medicinenet.com/script/main/art.asp?articlekey=2413
- https://www.researchgate.net/publication/320182585_Difference_Between_T_Cells_and_B_Cells
- https://education.seattlepi.com/functional-difference-between-t-cells-b-cells-4573.html
- https://biodifferences.com/difference-between-t-cells-and-b-cells.html