Education Journalist | Study Abroad Lead
T-cells (also called T lymphocyte) are a type of blood cell. T-cells are white blood cells (WBCs) in the lymphocyte class, which are an essential part of an immune system. They protect the body against infection. The primary function of T-cells is to fight infection. A variety of distinct types of T-cells are capable of identifying, attacking, and eliminating infectious agents in many ways. Immune cells are crucial to the body's ability to resist infection. T cells help in the activation of B cells.
| Table of Content |
Key Terms: T-cell, Helper T-cell, Regulatory T-cell, Cytotoxic T-cell, Function, Covid 19, B-cell, Immune system, Infection, Lymphocyte, Immune cell
Types of T-cell
[Click Here for Sample Questions]
T cells are categorised into 3 different types:
- Helper T cell
- Regulatory T cell
- Cytotoxic T cell
Helper T cell
Also known as CD4+ cells, is a kind of WBC that helps in serving as a key mediator of an immune system. The helper T cell is crucial to the regulation of immune responses. It produces factors that activate almost every other cell of the immune system. The surface of helper T cells is covered with a protein called CD4. The major histocompatibility complex (MHC) molecule, which helps the immune system recognize foreign substances, binds to this protein, which is essential for the activation of helper T cells. Helper T cells consist of B cells, cytotoxic t cells, macrophages, and other cells. Antibodies are produced by b cells which help in fighting infections and viruses, cytotoxic cells kill all the cells which are infectious, and macrophages attack diseases causing agents.
Regulatory T cells
It contains CD4 on their surface, but they do not activate the immune system as helper T cells do. Regulatory T cells act as protective cells, interrupting the immune response when it is no longer necessary. They prevent excessive tissue and cellular damage. Regulatory T cells work in several ways to suppress the immune response, including:
- By producing anti-inflammatory cytokines, the immune system is suppressed.
- Regulatory T cells release those molecules which attack and kill all the activated immune cells.
- They change dendritic cells' behavior as not to active T cells.
The Cytotoxic T cell has a co-receptor on the surface of the cell named CD8. CD8 acts as a link between the T cell receptor and MHC class I molecules, forming a bridge. This link enables cytotoxic T cells to identify normal cells infected with a pathogen. When a cytotoxic T cell identifies an infected cell, it activates and generates chemicals that kill the infected cell while also killing the pathogen.
T cell Activate
[Click Here for Sample Questions]
T cells become activated when they come into contact with antigens. Antigens are engulfed and digested by antigen-presenting white blood cells like macrophages. Antigen-presenting cells collect antigen-specific molecular information and bind it to an MHC class II molecule. After that, the MHC molecule is transferred to the cell membrane and displayed on the antigen-presenting cell's surface. Any T cell that detects a specific antigen will use its T-cell receptor to connect to the antigen-presenting cell.
The antigen-presenting cell secretes cell signalling proteins termed cytokines when the T-cell receptor connects to the MHC molecule. Cytokines activate T cells by signalling them to kill a specific antigen. T cells that have been stimulated multiply and develop into helper T cells. To kill the antigen, helper T cells trigger the creation of cytotoxic T cells, B cells, macrophages, and other immune cells.
Functions of T cell
[Click Here for Sample Questions]
- They may recognize foreign antigens and destroy infected cells as part of the adaptive immune response.
- They can also serve as 'helper' cells by interacting with B cells and developing them into antibody makers.
- T cells may also become regulatory, suppressing an immune response after an infection has ended.
Difference Between Helper T cell and Cytotoxic T cell
[Click Here for Sample Questions]
| On the basis of | Helper T cell | Cytotoxic T cell |
|---|---|---|
| Meaning | T Helper cells are T cells that tell B cells and other immune cells how to react to an infection to develop an immune response. | T Cytotoxic Cells are T cells that kill cancer cells and virus-infected cells by damaging their membranes directly. |
| After the Infection | When the virus is gone, T helper cells slow down the immune response. | Because of the activation, T Cytotoxic Cells continue to kill. |
| Ability to kill directly (pathogens) | Helper T cells do not have the ability to kill the infected cells directly. | Cytotoxic T cells have the ability to kill the infected cells directly. |
| Function | T Helper cells perform a variety of tasks, including stimulating B cells, macrophages, suppressor T cells, and activating killer T cells. | The primary role of T Cytotoxic Cells is to destroy antigens directly. |
What is the Role of T-cell in Covid-19?
[Click Here for Sample Questions]
T cells make antibodies that play an important role in the immunological response to viral infection. When the COVID-19 -causing SARS-CoV-2 virus infects epithelial cells, such as those present in the air, it multiplies inside the cells utilising the biochemical machinery of the host cell. The host cell dies as a result of this, producing chemicals known as damage-associated molecular patterns e.g. nucleic acids and oligomers.
Also Read:
| Related Articles | ||
|---|---|---|
| HIV and AIDS | Malaria | Dengue |
| Filariasis | Ascariasis | Typhoid |
| Pneumonia | Common Cold | Amoebiasis |
| Algal bloom | Biomagnification | What is Cancer |
Things to Remember
[Click Here for Sample Questions]
- T cells are lymphocyte immune cells that defend the body against diseases as well as cancer-causing cells.
- Cytotoxic T cells employ granule sacs containing digestive enzymes to actively kill infected cells.
- Helper T cells activate cytotoxic T cells, macrophages, and B cell lymphocytes, as well as stimulate antibody synthesis.
Sample Questions
Ques. Where are B-cells and T-cells formed? How are they different from each other? (2 marks)
Ans. The lymphocytes B-cells and T-cells are generated in the bone marrow. B-cells are responsible for manufacturing antibodies, whereas T-cells are responsible for assisting B-cells in the production of antibodies.
Ques. What is the Activation of T-cell? (1 marks)
Ans. The MHC Class II molecules produced on the surface of antigen presentation cells activate T helper cells when they are confronted with antigens.
Ques. If the thymus gland is removed from the body of a person, what would happen to the immune system? (1 marks)
Ans. T-lymphocytes are generated and matured in the thymus gland, and removing it weakens the immune system.
Ques. Are T-cells responsible for immunity? (2 marks)
Ans. T cells are immune cells that specialise in detecting certain foreign particles. T cells react only to the specific antigen they are exposed to, rather than attacking all antigens simultaneously. Therefore, T cells play an important role in the immune response to foreign substances.
Ques. What is the difference between the role of T-cell and B-cell? (3 marks)
Ans.
- The immune system's B-cells (B lymphocytes) and T-cells (T lymphocytes) are produced in the bone marrow. T-cell differentiation occurs in the thymus.
- In reaction to foreign substances (antigens) such as viruses and pollen, B-lymphocytes create antibodies. Immunoglobulins are antibodies. They're unique to each antigen. For each antigen, there are many antibodies.
Antibodies attach to antigens, but they don't kill them. Other mechanisms are used to combat this. Allergies are caused by allergens, which are weak antigens.
- 3. T-cells produce three types of cells in response to pathogens: killer T-cells, helper T-cells, and suppressor T-cells. T lymphocytes may assist B lymphocytes in producing antibodies or directly eliminate the infection (killer T-cells).
When B- and T-cells are activated, they both create memory cells. These have a lengthy lifespan and are the foundation of acquired knowledge.
Ques.What are the two special types of lymphocytes in humans? How are they different in their role in the immune system? (3 marks)
Ans. Two types of lymphocytes in humans are :
- B-lymphocytes
- T-lymphocytes
| B-lymphocytes or B-cells | T-lymphocytes or T-cells |
|---|---|
| B-cells produce antibodies against the antigen or virus. They do not react to organ transplant. | T-cells stimulate B-cells to produce antibodies against antigen. T-cells responds to organ transplant. |
Ques. What are the similarities between B-cells and T-cells? (3 marks)
Ans.
- They both are produced in the bone marrow.
- B-cells and T-cells are found in peripheral blood.
- Both involve adaptive immune responsiveness.
- T-cell and B-cell are morphologically similar.
Ques. What is the basic difference between helper T-cell & cytotoxic T-cell? (3 marks)
Ans. The primary distinction between cytotoxic T cells and helper T cells is that cytotoxic T cells kill virus-infected cells and tumour cells, whereas helper T cells generate cytokines that activate or control other immune system cells to initiate a particular immunological response. In addition, cytotoxic T cells play a role in cell-mediated immunity, whereas helper T cells function as antigen-presenting cells for B cells to activate.
Ques. Describe the role of T-cell and antibodies in immunity in COVID- 19? (3 marks)
Ans. T cells, like B cells that make antibodies, play an important role in the immunological response to viral infection. When the COVID-19-causing SARS-CoV-2 virus infects epithelial cells, such as those found in the air, it multiplies inside the cells using the biochemical machinery of the host cell. The host cell dies as a result of this, releasing chemicals known as damage-associated molecular patterns. These chemokines and other cytokines subsequently attract monocytes, macrophages, and T cells to the infection site, causing further inflammation. The recruited T cells create interferon-gamma as part of the inflammatory response.
For Latest Updates on Upcoming Board Exams, Click Here: https://t.me/class_10_12_board_updates
Check-Out:
Comments