B lymphocytes are the cells of the immune system that make antibodies to invade pathogens like viruses. They form memory cells that remember the same pathogen for faster antibody production in future infections.

Memory cells arise from T-cell dependent reactions in the germinal center and are the critical cell type for immune response to re-challenge from an antigen. Although, like plasma cells, memory B cells differentiate from the GC reaction, they do not secrete antibody and can persist independently of antigen [85].

Costimulatory signals provided by another specialized cell in a peripheral lymphoid organ are also required. As part of the adaptive immune response, some lymphocytes proliferate and differentiate into memory cells, which are able to respond faster and more efficiently the next time the same pathogen invades.

Memory cells are long-lived immune cells capable of recognizing foreign particles they were previously exposed to (thus, the memory in their name). Memory B cells are clones of a parent B cell that previously served as an antigen-presenting cell and then activated by a helper T cell to proliferate.

In addition to the spleen and lymph nodes, memory B cells are found in the bone marrow, Peyers’ patches, gingiva, mucosal epithelium of tonsils, the lamina propria of the gastro-intestinal tract, and in the circulation (67, 71–76).

thymus

Antibodies are produced by specialized white blood cells called B lymphocytes (or B cells). When an antigen binds to the B-cell surface, it stimulates the B cell to divide and mature into a group of identical cells called a clone.

A lymphocyte is a type of white blood cell that is part of the immune system. There are two main types of lymphocytes: B cells and T cells. The B cells produce antibodies that are used to attack invading bacteria, viruses, and toxins.

B cells produce and secrete antibodies, activating the immune system to destroy the pathogens. The main difference between T cells and B cells is that T cells can only recognize viral antigens outside the infected cells whereas B cells can recognize the surface antigens of bacteria and viruses.

Without B-cells, your body would not be as effective at fighting off a number of common bacteria and viruses; and you would lack the long-lasting “memory antibody” function that is typical after recovering from an infection or after being immunized against a specific infectious invader.

In a T-dependent immune response the B cells need assistance from T cells in order to respond. In this situation activated B cells move to the border of the T cell zone to interact with T cells (Figure 2). CD40 ligand is found on these T helper cells and interacts with CD40 on the B cells to form a stable attraction.

Armed helper T cells activate B cells when they recognize the appropriate peptide:MHC class II complex on the B-cell surface (Fig. 9.5).

Helper T-cells stimulate B-cells to make antibodies and help killer cells develop. Killer T-cells directly kill cells that have already been infected by a foreign invader. T-cells also use cytokines as messenger molecules to send chemical instructions to the rest of the immune system to ramp up its response.

The main parts of the immune system are: white blood cells, antibodies, the complement system, the lymphatic system, the spleen, the thymus, and the bone marrow.

Your immune system can also be weakened by smoking, alcohol, and poor nutrition. AIDS. HIV, which causes AIDS, is an acquired viral infection that destroys important white blood cells and weakens the immune system. People with HIV/AIDS become seriously ill with infections that most people can fight off.

Bone marrow That is where most immune system cells are produced and then also multiply. These cells move to other organs and tissues through the blood. At birth, many bones contain red bone marrow, which actively creates immune system cells.

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