Difference Between T Cells And B Cells

The difference between T cells and B cells is that the lymphocytes that remain in the bone marrow for differentiation are known as "B-cells,". In contrast, the lymphocytes that migrate to the thymus are "T-cells."  Their mode of action against fighting pathogens is different.  For example- when any pathogen enters the body, T cells recognize it, stimulate different T cells and start making clones.  This is how they increase their number and fight against pathogens.  

However, the B cells, are first activated by T cells, and they also start multiplying and creating copies of memory B cells and plasma cells that migrate to the infection site (lymph).  If the same virus or bacterium re-infects a person, memory B cells can promptly eliminate the antigens. 

What are B Cells?

B cells or lymphocytes are in charge of producing antibodies and providing humoral immunity. They make up 25% of all lymphocytes. They release cytokines that draw in additional immune cells. In reaction to the antigens, these cells develop in the bone marrow and create antibodies. B cells create memory B cells and plasma cells when they come into contact with antigens.

Antibody production occurs in plasma B cells, referred to as effector cells. Specialized cells called plasma cells make protective proteins and release them into the blood. If the same virus or bacterium re-infects a person, memory B cells can promptly eliminate the antigens since they have a lengthy lifespan. The antibody molecules might stay free or bind to a cell membrane. Therefore, B cells create antibodies or immunoglobulins (Ig) that are targeted at the pathogens that have infiltrated the body. The bone marrow produces new B-lymphocytes every few days since they have a short lifespan.

B Cells Functions

Some of the functions performed by B cells are discussed below:

• Antibody production: B cells are primarily responsible for producing antibodies.
• Antigen presentation: B cells can also present antigens to T cells, initiating immune responses and promoting coordination between different immune cells.
• Memory cell formation: B cells can differentiate into memory B cells after encountering antigens, providing long-lasting immunity upon re-exposure to the same pathogen.
• Regulation of immune responses: They can modulate immune responses by releasing cytokines and interacting with other immune cells, contributing to the regulation of inflammation and immune tolerance.

What are T Cells?

T cells control the immunological response mediated by cells, making up around 75% of the circulating lymphocytes. They originate from bone marrow hemocytoblasts, and when they move to the thymus, they are referred to as T-cells. These immature cells, known as thymocytes in the thymus, develop into T lymphocytes. Thymosin, a local polypeptide hormone, encourages this maturation process. 

After being stimulated by antigens , the T cell divides rapidly and forms a clone of cells known as lymphoblasts. These clones are morphologically similar and can react specifically with the same antigen but perform different functions.  Four different T-lymphocyte subtypes are present in the clone: Helper T-cells, Suppressor T-cells, Memory T-cells and Killer T-cells.

T Cells Functions

Some of the functions performed by T cells are discussed below:

• Directly attack and kill infected or abnormal cells.
• Regulate immune responses by activating other immune cells or suppressing excessive reactions.
• Provide long-term immunity through memory T cells, which respond rapidly to reinfection.
• Coordinate immune responses by releasing signaling molecules called cytokines.
• Help in the elimination of pathogens and infected cells through immune surveillance and activation of other immune cells.

Difference Between B-Cells and T-Cells

The difference between B cell and T cell table is given below:

Similarities Between B Cells and T Cells

Besides differences, there are some similarities between B cells and T cells:

• Both are lymphocytes, therefore known as B and T lymphocytes.
• They are produced in the bone marrow.
• Fight against pathogens through different immunity mechanisms.
• Both B cells and T cells have antigen receptor sites on them. For example-BCR in B cells and TCR in T cells.
• Both are motile and consist of a large nucleus.
• They are found in lymphoid organs.
• Both multiply in bulk so that they can give a tough fight to pathogens.

Conclusion - Difference Between T Cells and B Cells

The difference between T cells and B cells is evident in their origin and mode of action within the immune system. B and T cells are immune cells that protect us from invading pathogens by adopting different mechanisms. B cells adopt humoral or antibody-mediated immunity (AMI) whereas T cells adopt cell-mediated immunity (CMI) to kill the pathogens. However, the basic principle remains the same, both multiply themselves to kill pathogens. Nevertheless, B cells depend upon T cells for stimulation. They also share some similarities as well.

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