Question

1. What are the various types of B cells, and how do the types differ?

2. What are the various types of T cells, and how do the types differ?

3. How does an immune response differ if a pathogen is encountered again one year later?

Answer 1

1. Types of B cells

a. The transitional B Cells : They represents initial stage of B cells from their formation in bone marrow till their migration in secondary lymphoid organs.

b. The Follicular B Cells (FoB) or B-2 : They are considered naive B cells.

c. The Marginal zone B Cells (MZB) : These B cells are located at the margins of spleen as guards.

d. B1 B Cells : These are the first B cells formed in fetal liver.

e. Plasmocyte or Ab-secretory cells: These are antibodies secreting B cells.

f. Memory B Cells: Retain antigens memory.

g. Regulatory B Cells (Bregs): They release various cytokines and maintain the fine equilibrium required to guarantee tolerance.

2. Types of T cells:

a. CD4+ Helper T cells: They help in the maturation of B cells into plasma cells and memory cells. They also activate macrophages and Cytotoxic T cells. Activated by MHC class 2 molecules.

b. CD+ Cytotoxic T cells: They kill virus infected or tumour cells. Activated by MHC class 1 molecules.

c. Memory T cells: They provide information about previous encounters with the antigen.

d. Suppressor T cells: They inhibit the over activity of other lymphocytes and keep the immune system in regulated state.

3. Our immune system generates a primary response when it encounters the antigen for the first time. Primary immune response is usually mild but during primary immune response memory cells are produced. When the same pathogen is encountered by the immune cells again then our immune system generates secondary immune response. Secondary immune response is far more vigorous than the primary immune response due to the presence of memory cells.