White blood cells (WBC) play a crucial role in immunity.
There are five different kinds of WBCs — eosinophil, basophil, neutrophil, monocyte and lymphocyte. Among these, the most important are lymphocytes, which include the T lymphocytes and the B lymphocytes. However, the others also have important roles to play as supporting cast.
T cells and B cells are the most critical components of the adaptive immune system. These cells are essential for fighting disease and play an important role in regulating hypersensitivity to harmless or “self” antigens.
Formation: T cells and B cells originate from the same cell known as the hematopoietic stem cell, which forms in the bone marrow. Through differentiation processes, hematopoietic stem cells eventually form into B cells and T cells.
T Cells or T lymphocytes
B Cells or B lymphocytes
T cells protect us from infection: T-cells play a plethora of roles in immunity — as killer cells that can attack an infected cell and kill it along with the infecting agent, and as suppressor cells that modulate the level of functioning of other lymphocytes.
B cells create antibodies: B lymphocytes, also called B cells, create a type of protein called an antibody. These antibodies bind to pathogens or to foreign substances, such as toxins, to neutralize them.
Helper Tcells release cytokines that direct the immune response. In contrast, cytotoxic T cells produce deadly granules that kill pathogen-infected cells.In addition to helper T cells and cytotoxic T cells, there are also memory T cells.Main feature of Memory T cells is they can quickly mobilize a specific immune response long after an infection has been eliminated.
The main function of B cells is the recognition of antigens followed by differentiation into plasma cells which release antibodies to fight infection. Cytokines are important signaling proteins that trigger other B cells to proliferate and differentiate into plasma cells. These plasma cells release antibodies that are specific to the antigen that was initially bound to the B cell in the first place.
T cells are involved in cell-mediated immunity
B cells are primarily responsible for humoral immunity (related to antibody production)
T cells recognize viral antigens outside the infected cells
B cells can recognize the surface antigens of bacteria and viruses directly.
Difference between T cells and B cells
T cell activation process
B Cell activation process
T cells and B cells are part of a specialized network of immune cells that specifically respond to pathogens and fight off infections. When a pathogen enters your body, our immune system responds in various ways to address the threat. These threats are hugely variable, so the immune response must be highly adaptable.
As such, immune cells such as T cells and B cells are required to fight infections in different ways. B cells and helper T cells use the information gathered from the unique surface antigens on pathogens to trigger the production antibodies. Millions of antibodies cycle through the body and attack the invaders until the worst of the threat is neutralized. T cells can also detect infected cells and use cytokines as messenger molecules to the rest of the immune system to ramp up its response. Cytotoxic T cells directly kill cells that have already been infected by a foreign invader.
When B cells and T cells identify antigens, they can use that information to recognize invaders in the future. So, when a threat revisits, the cells can swiftly deploy the right response to tackle it before it affects any more cells. That’s how you can develop immunity to certain diseases.
Kinds of immunity
Immunity is of two kinds — innate and acquired.
The defence mechanisms that the body is born with is known as innate immunity. This includes something as simple as the ability of the skin to prevent inner, more vulnerable tissues, from coming in contact with the external environment. Acquired immunity, as the name suggests, is something that develops over time through exposure to pathogens or disease causing agents like virus and bacteria. Acquired immunity kicks in either through antibodies (this is known as humoral immunity) or through cells programmed to destroy invading organisms by causing the dissolution of the very cells that have been infected.
How do vaccines work with our immune system?
The immune system has memory. It can respond more rapidly and effectively to pathogens it’s previously come across. Before we had a vaccine for chickenpox, if you were exposed to the virus as a kid, you were largely protected from getting it again. That’s because your memory B cells and T cells recognize and neutralize the virus before it causes issues.
Thanks to the memory of T cells and B cells, vaccines can keep us from getting sick, or they make the infection much less severe. For example, the COVID-19 mRNA vaccines work by giving instructions to your cells to create a harmless portion of the coronavirus that T cells and B cells recognize and store in their memory. That way, if you’re exposed to the virus, your memory B and T cells will rapidly respond and destroy the virus.
mRNA vaccines are now also being investigated in cancer care, such as using an mRNA vaccine to prevent a colorectal cancer recurrence.