Adaptive & Specific Immunity Flashcards
Humoral Immunity
protective molecules (mainly antibodies) carried in the fluids of the body
Cell-Mediated Immunity
The type of immune responses brought about by T cells, such as cytotoxic, regulatory, and helper effects. An activated T cell interacts directly with antigen-bearing cells in order to bring about its end result
Antigen
any cell, particle, or chemical that has properties that allow it to stimulate a specific immune response by B cells or T cells
Antibody
a large protein molecule evoked in response to an antigen that interacts specifically with that antigen
Titer
a measure of antibody levels in a patient’s serum or specimen, as determined by agglutination methods
Seroconversion
T marker (receptor)
binds free antigens
B marker (receptor)
bind processed antigens together with MHC molecules on antigen presenting cells
Immunocompetence
the ability of the body to recognize and react with multiple foreign substances
Antiserum
Antibody-rich serum derived from people who have recovered from specific infections such as hepatitis; sometimes taken from the blood of animals deliberately immunized against an infectious or toxic antigen. Used in passive immune therapy
Origin of all cells
all cells rise from stem cells in bone marrow
Properties of B cells
- differentiate in bone marrow
- humoral response: stimulated by an antigen to produce specific antibodies
- defends against bacteria, protozoans, and fungi
Properties of T cells
- differentiate in the thymus
- cell-mediated response: stimulated by an antigen inside a host cell or in a cell membrane
- defends against viruses and cancer cells
Properties of B AND T Cells
- Found in lymphatic tissue
- Migrates to secondary lymphoid tissue (lymph nodes)
- Millions of distinct B & T cells develop and migrate to lymph nodes, spleen, GALT (SALT, MALT)
MHC-1
markers display unique characteristics of “self” and allow for recognition
MHC-2
- receptors that recognize and react with “non-self” (foreign antigens)
- Found on Antigen Presenting Cells (APCs): macrophages, dendritic, and B cells; important for presenting to T cells
Receptor Gene Rearrangement
- We have 500+ genes that code for the variable tips of all antibodies. 100s of genes code for millions of distinct surface receptors
- During early embryonic development, stem cells rapidly differentiate
- Early embryonic lymphocyte genes randomly shuffle generating millions of new gene combinations -> massive variation before you are even born
- We have everything we need; it;s just a matter of using them at the moment we need them
Clonal Deletion Theory
- Lymphocytes do not attack our own cells normally
- during embryonic development all lymphocytes with “self” antigens ar removed (organism develops tolerance to itself)
- Result: you are born with a passive pool of genetically distinct, immature lymphocytes called clones which will protect you from pathogens for the rest of your life. Each clone bears a different receptor which will react with only a single type of antigen.
- clones carrying a specificity for self molecules are eliminated and immune tolderance is achieved. Result = a repertoire of lymphocyte clones each with unique receptors
Clonal Selection Theory
- Explains development of lymphocyte specificity and variety during maturation of the immune system
- Lymphocytes circulate in the lymphatic organs, encounter an invading antigen, and only clones with matching surface receptors bind.
- Selected clones proliferate (multiply by mitosis)
- Selected clones migrate home to the lymphatic organs ready to encounter antigens
B-Cell Clonal Selection Theory
- B-cell binds to antigen and responds by proliferating
- Some b-cells turn into Memory Cells (which are kept forever) and some turn into Plasma Cells (which are the ones that FIGHT by secreting antibodies into circulation)
- T-cell clones respond to specific antigens in a similar way
self-tolerance
the ability of the immune system to recognize self-produced antigens as a non-threat while appropriately mounting a response to foregin substances
Characteristics of Antigens
- Large, complex protein, mwt = 10,000+ (sometimes a lipo/glycol/nucleoprotein or a polysaccharide)
- located on the surface of all cells and viruses
- recognized by Immune System as “non-self”
- each antigen is made of many epitopes: the portion of a foreign cell or cirurs that is the precise stimulus of an immune response
Haptens
- molecules that are too small to elicit an immune response
- a single epitope that may bind to a carrier group (e.g. plasma protein)
- Ex: penicillin, household chemicals)
Hydralazine can cause drug-induced Lupus erythematosus
The Humoral Response Antigen Entrance, and Processing Clonal Selection
- Macrophages, b-cells and t-cells work together
- specific B-lymphocytes bind to pathogen surface receptors (PAMPs)
- B-cell clones are selected and activated
- Selected b-cell rapidly divides
- product cells mature into plasma and memory b-cells
- plasma cells synthesize and release antibodies (2000 Ab/sec)
