Serology Day 1 - Immune system, immunoglobulins, complement Flashcards
Antigen
Molecule that is capable of eliciting formation of antibodies in an immune competent host
Reacts with antibody or t cell
Not able to evoke IR in first place
Antibody
GlycoPROTEIN binds w/ antigen “lock & key”
Produced by B cells and plasma cells in response to a foreign substance exposure
Aka immunoglobulins
Immunogen
Any substance that is capable of inducing a humoral or cellular IR and combine with it
Immunoglobulin structure
Y shaped - 2 heavy chains & 2 light chains (kappa, lambda)
2 Fab regions
1 Fc region
The larger the hinge region the greater the chances of degredation
Fab
Antibody binding region of monomer.
Contains 1 heavy and 1 light chain
Fc
Crystallizable region. Contains 2 heavy chains. Complement fixation occurs here
Immune system
Defense mechanism
Mammels - rid host of pathogens
Invertebrates - some immune response
Ability to distinguish self
Recognition phase
Self ➡️ normally no I.R.
Non-self ➡️ response phase
Innate (natural) immunity
Most primitive General recognition Antigen independent First line Rapid Non-specific (physical and chemical barriers)
Adaptive (acquired) immunity
- specific recognition of small portion of organism or antigen (antigen dependent)
- memory of initiator
- eliminate self reacting cells
- 2 types: humeral and cell mediated
- lag time between exposure and Max response
Autoimmunity
When self-reacting cells persist and are not destroyed.
Abnormal I.R. to host’s cells or tissue.
Antibody or cell mediated
Innate immune defenses in body
Flushing of urinary tract, pH GI Flora Stomach acid pH Antimicrobial in saliva, tears Physical barriers: cillia, mucus Skin - fatty acids, Flora
Leukocytes
Wbcs
Neutrophils (polymorphonuclear neutrophilic leukocyte) PMN
Removes infectious agent by phagocytosis
Most abundant in circulation 55-75% of wbcs
Granulocyte
Nucleus
- mature PMN - multi-lobed (segmented) - immature PMN - non-segmented bands
Monocytes
2-9% of wbcs
Agranulocytes
Nucleus - convoluted and Lacy
Cytoplasma - large amount of grey/blue w/small purple granules
Quickly removed from bloodstream to tissues where they become macrophages and histiocytes.
Interleukins produced by T Helper 2’s
IL-4, IL-5, IL-6
All help activate B cells so they can become plasma cells and produce antibodies
Plasma cells
Differentiated B cell, no longer has membrane IgM or IgD
Each plasma cell secretes an antibody with a specific variable portion (matches with a specific epitope)
Memory B cell
Long-lived, circulate through blood to lymphoid tissues
Have high levels of complement receptors/adhesion molecules
Repeat activation of a Memory B cell much easier than Mature B cell
Epitope (antigenic determinant)
Structure on antigen that elicits antibody response
Isotype
Changes in constant region of heavy chains which results in different classes of immunoglobulins (IgG, IgM, IgD, etc)