Unit A 17 Phys, Immune System Focus on B Cells

Antigen

Each B cell has surface B cell receptors (BCRs) for binding with one specific type of ____________________. The BCRs are antibody molecules made by that cell. Unlike T cells, B cells do not need an antigen presented to them on a MHC receptor

Antibody

Each B cell has surface B cell receptors (BCRs) for binding with one specific type of antigen. The BCRs are ___________________ molecules made by that cell. Unlike T cells, B cells do not need an antigen presented to them on a MHC receptor

Plasma cells

Antigens bind with BCR and stimulate B cells to divide and become ____________________ (effector B cells) and memory cells.

Memory cells

Antigens bind with BCR and stimulate B cells to divide and become plasma cells (effector B cells) and _________________________.

Plasma cells

Most B cells differentiate into active __________________________ that produce antibodies (up to 2,000 per second) that bind the same antigen as the B cell receptor (BCR).

Rough endoplasmic reticulum

Plasma cells differ from B cells in that they swell as they add large amounts of __________________________ for protein production

Helper T cells

Although B cells can be activated by free antigens, enhanced B cell activation requires ___________________ (CD4+ cells).

Cytokines

Activated Helper T cells secrete __________________ that helps promote B cell differentiation into plasma cells and memory B cells.

Receptor mediated endocytosis

When the B cell receptor binds to an exogenous antigen (bacteria, viruses, fungi, protozoa, polysaccharides, and toxins), the B cell internalizes the antigen by ________________________, processes it (beaks it apart), attaches the pieces to MHC class II molecules that are transported to the plasma membrane. The peptide/MHC II complex can then present to and activate Helper T cells. Note that B cells can also use MHC class I molecules to activate cytotoxic T cells.

MHC class II molecules

When the B cell receptor binds to an exogenous antigen (bacteria, viruses, fungi, protozoa, polysaccharides, and toxins), the B cell internalizes the antigen by receptor mediated endocytosis, processes it (beaks it apart), attaches the pieces to _________________________ (use abbreviation and specific class) that are transported to the plasma membrane. The peptide/MHC II complex can then present to and activate Helper T cells. Note that B cells can also use MHC class I molecules to activate cytotoxic T cells.

Primary response

Plasma cells are prolific producers of customized antibodies. Formation and production of takes several days after exposure to an antigen & peak antibody production may occur a week or two after exposure. This is referred to as the _______________________.

Secondary response

Memory cells remain dormant but respond quickly if exposed to the antigen a second time. Memory cells are responsible for the __________________________, which is a response so fast & effective that infection is typically prevented.

Memory cells form the basis for long-term immunity

Memory cells

Memory cells remain dormant but respond quickly if exposed to the antigen a second time. Memory cells are responsible for the secondary response, which is a response so fast & effective that infection is typically prevented.

____________________ are the type of cells that form the basis for long-term immunity

Clonal expansion

Once B cells come into contact with an antigen that binds to B cell receptors, the B cell becomes activated. The B cell then divides by mitoses in a process called _________________________, producing lots of plasma cells and memory cells. T helper cells can enhance this process.

Titer

An antibody ________________ is a type of blood test that determines the presence and level of specific antibodies in the blood. Note that plasma cells can become memory plasma cells or long-lived plasma cells and secrete antibodies for months, years or a lifetime.