Adaptive immune system cells are the T lymphocytes and B lymphocytes cells that help in the development of adaptive immunity against the antigens.

Adaptive immunity is developed when an antigen enters the body and the lymphocytes cells create antibodies to fight against them. Lymphocytes, which are white blood cells, are formed with other blood cells in the red bone marrow found in many flat bones, such as the shoulder or pelvic bones. The two types of lymphocytes of the adaptive immune response are B cells and T cells. Whether an immature lymphocyte becomes a B cell or T cell depends on where in the body it matures. The B cells remain in the bone marrow to mature (hence the name “B” for “bone marrow”), while T cells migrate to the thymus, where they mature (hence the name “T” for “thymus”).

B cells produce antibodies whereas T cells (a diverse group of cells) promote the destruction of microbes residing in phagocytes, or the killing of infected cells to eliminate reservoirs of infection. T cells do not produce antibody molecules. They have antigen receptors that are structurally related to antibodies. These structures help recognize antigens only in the form of peptides displayed on the surface of antigen-presenting cells.

T and B cells exhibit a common theme of recognition/binding of specific antigens via a complementary receptor, followed by activation and self-amplification/maturation to specifically bind to the particular antigen of the infecting pathogen. T and B lymphocytes are also similar in that each cell only expresses one type of antigen receptor.

Practice Questions

 Khan Academy   

A clinical approach to anemia: solve the case

MCAT Official Prep (AAMC)

Biology Question Pack, Vol. 1 Passage 18 Question 112

Biology Question Pack, Vol 2. Passage 17 Question 109

Practice Exam 2 B/B Section Passage 9 Question 52

Sample Test B/B Section Passage 6 Question 32

Key Points

• The adaptive immune response is slower to develop than the innate immune response, but it can act much more powerfully and quickly than the innate immune response against pathogens that it has seen before.

• B and T cells are lymphocytes, or white blood cells, which can recognize antigens that distinguish “self” from “other” in the body.

• B and T cells that recognize “self” antigens are destroyed before they can mature; this helps to prevent the immune system from attacking its own body.

Key Terms

B cell: a lymphocyte, developed in the bursa of birds and the bone marrow of other animals, that produces antibodies and is responsible for the immune system

T cell: a lymphocyte, from the thymus, that can recognize specific antigens and can activate or deactivate other immune cells

Antigen: a substance that binds to a specific antibody; may cause an immune response

Adaptive immunity: a specific type of immunity developed over time

Lymphocytes: white blood cells involved in adaptive immunity

Antibody: protein produced in the blood to fight against an antigen