[WIP] 15 Adaptive Immune Response

Primary Response

The first response to an antigen

May take a week or more to develop

Secondary Response

This is the immune response when the immune system remembers a pathogen on subsequent exposure

Vaccines exploit this phenomenon of immunologic memory

» Under [__], memory B cells differentiate into plasma cells

→ rapid production of antibodies

Adaptive Immunity

Third line of defense, acquired throughout lifetime.

A specific response against a specific pathogen

• humoral: eliminates extracellular pathogens

• cell-mediated: eliminates intracellular pathogens

Humoral immunity

Subdivision of adaptive immunity that eliminates extracellular pathogens

(humor means “fluids” → mediates invades in blood/tissue fluids)

Mediated by B cells

• mature in bone marrow

• some differentiates into plasma cells → produce antibodies

  • antibodies: Y-shaped proteins that bind to specific antigens and mark them as invaders to be eliminated

• some differentiate into memory cells → allows rapid secondary response if encountering antigen again

Cell-mediated immunity

Subdivision of adaptive immunity that eliminates intracellular pathogens

Mediated by T cells

• mature in thymus

• differentiates into:

  • cytotoxic T cells → delivers “death packages” that activate apoptosis of cell

  • Helper T cells → delivers cytokines to macrophages to increase their killing power; helps B cells proliferate into plasma cells

  • regulatory T cells (suppressor T cells)

• for every T cell, there’s a B cell that produces specific antibodies

Antigen

Any compound that elicits an immune response (immunogen) → antibody production. Antibody generator.

Epitropes

Antigenic determinants on surface of microbes that trigger response; are macromolecules (proteins, lipids, polysaccharides)

When an antibody binds to an antigen, it is actually binding to an [__] of the antigen!

Antibodies

[__] are also called immunoglobulins

Structure

• 4 amino acid chains held together by disulfide bonds

• Y-shaped proteins with two general parts

  • Fc region: stem portion of [__]; serves as a constant “red flag" that sticks out from the surface of all antibody-bound antigen → tags antigen

  • Fab region: arms that attach to antigen→ variable region

    • » unique to each Antibody (Ab)

    • » recognizes and binds to a specific Antigen (Ag)