Adaptive Immunity

Adaptive Immunity

Immunity that provides a specific target defense and develops a memory

Antigens

Molecules on the surface of microbes, infected cells, or abnormal tissue that act as molecular targets for antibodies

Immunogen

Type of antigen that binds to receptors and induces immune responses

Hapten

Type of antigen that binds to receptors but can’t induce immune responses until they bind with a larger molecule

Lymphocyte

WBC that plays different roles in immunity, includes T and B cells

Humoral Immunity

Immunity mediated by B cells, uses antibodies to recognize antigens, works against extracellular pathogens

Cellular Immunity

Immunity that is mediated by T cells, works against intracellular pathogens and abnormal cells

Active Immunity

Immunity that develops after your own immune system is exposed to an antigen, is long-lived and has a memory

Passive Immunity

Immunity that is provided by preformed antibodies or T cells that are delivered, no memory and is temporary

B Cells

Lymphocytes that develop and mature in bone marrow, each cell responds to one specific antigen, involved in humoral immunity

T Cells

Lymphocytes that develop in the thymus and mature in lymphoid tissue, involved in cellular immunity

Major Histocompatibility Complex

Glycoproteins on the surface of human cells (not RBCs) that present antigen peptides to T cells (MHC)

MHC Class I

MHC that presents endogenous (intracellular) antigens

MHC Class II

MHC that presents exogenous (extracellular) antigens

T-Helper Cells

Cells that have CD4 molecules on their surface, activate other cells after MHC class II cells present antigens to them (Th)

Th1

Th cell that works to develop cellular immunity with Tc cells

Th2

Th cell that works to develop humoral immunity with B cells

Th17

Th cell that secretes lymphokines to activate macrophages

Treg

Th cell that limits immune response

Superantigens

Special class of antigens that hyperactivate T cells by binding outside the antigen binding site, causes excessive cytokine production and systemic inflammation

T-Cytotoxic Cells

Cells that have CD8 molecules on their surface, reacts with antigens on virus infected cells or cancer cells presented by MHC class I, kills cells

Plasma Cells

Differentiated B cells that secrete antibodies

Memory Cells

T and B cells that have differentiated, are long-lived but remain inactive until another antigen exposure

IgG

Antibody that is the most abundant, protects against infections, is transported across the placenta

IgA

Antibody that is found in blood and bodily secretions such as tears and breast milk

IgM

Antibody that is the largest and the first antibody produced during a primary response, made during neonatal stage

IgD

Antibody that functions as a type of B cell antigen receptor on early B cells

IgE

Antibody that defends against parasitic infections by causing inflammation, common cause of allergies

Class Switch

Change in antibody production from one class to another

Antibodies

Proteins produced by plasma cells that bind to antigens, function in neutralization, agglutination, and precipitation, also called immunoglobulins

Primary Response

Initial exposure to antigen, antibodies/T cells initiated, 1-2 weeks, seroconversion, and a switch from IgM to IgG

Seroconversion

Change in blood serum from antibody-negative to antibody-positive

Secondary Response

Subsequent exposure to same antigen, more rapid, more antibodies produced (mainly IgG)

Acquired Immunity

Immunity you develop in your lifetime