Immune System pt 2 Flashcards
what are the features of specific immune response
- specificity
- diversity
- memory
- self-tolerance
what are the specific defense mechanisms
humoral and cell-mediated immunity
describe humoral immunity
- B cell mediated
- B cells turn to plasma cells to secrete antibodies
- able to defend against bacteria, toxins, viruses in body fluids
describe cell-mediated immunity
- T cell mediated
- T cells turn to active cytotoxic T cells to bind and kill abnormal body cells
- defend against bacteria and viruses hidden in infected body cells
- part of rxn to transplants and cancer cells
describe how specificity occurs in immune responses
- B and T cells bind and respond to antigens (each antigen has unique structure w/ epitopes [recognition sites])
- B and T cells recognize certain antigens thru antigen receptors on surface
- interacts/activates only lymphocytes w/ receptors specific for antigens on invader
draw out the antibody structure and include a separate structure for the antigen attaching to a specific antibody
….
describe B cell antigen receptors
- similar to antibody molecules except that they’re bound to membrane
- AKA membrane antibodies
describe T cell receptors
- same protein family as antibodies but are different in structure and are never secreted
- act only as cell surface receptors for antigen
describe how diversity plays a role in specific immune responses
- = capacity to recognize and respond to millions of dif antigens
- single B or T lymphocyte has ~100K antigen receptors all w/ same specificity
- each cell can detect a few million antigens that can enter body
describe clonal selection
- a single lymphocyte expresses receptors specific to a distinct antigen
- required for immune response
- 2 types of clones result from lymphocyte differentiation (effector/plasma and memory B cells)
describe effector/plasma cells
- combat same antigen that stimulated their production
- short-lived (4-7 day lifespan)
- secrete 2000 antibodies per second that bind to antigen
- antibodies circulate several weeks, binding to and marking antigens for destruction by phagocytosis and complement-mediated lysis
describe memory B cells
- have membrane receptors specific for same antigen
- long-lived
describe the relationship of chickenpox and shingles
- cp caused by varicella zoster virus
- virus can survive by travelling to dorsal root ganglia and remain dormant for years
- virus can reactivate and cause shingles due to age or stress (1 in 10)
describe the importance of memory in specific immune responses
- first exposure to antigen = primary immune response
- symptoms of illness occur (10-17 days)
- antigen-selected B and T cells proliferate and differentiate into effector cells
- this leads to acquired immunity
- secondary immune response is faster than primary (2-7 days) and is more prolonged bc of clones of memory T and B cells
- serum antibody conc is higher in secondary response than primary esp over short amt of time
describe self-tolerance in specific immune response
- B and T cells don’t attack normal cells
- programmed cell death (apoptosis) occurs w cells that have antigen receptors during development in bone marrow and thymus
- autoimmune diseases are caused by failure of self-tolerance
describe the role of B lymphocytes in antibody production for humoral immunity
- B cell exposure to antigen triggers clonal selection which increases memory B and plasma cells
- antigens that trigger production of both types of cells are T-dependent antigens
- IL-2 secreted from helper T cells + T-dependent antigens lead to activation of B cells
- no memory for subsequent exposures
describe antibody function in humoral immunity
- specific antigen binding which aids in inactivation or destruction of antigen
- tail involved in inactivation or destruction of antigen
- antigen-binding site recognizes and binds antigen
what are the major classes of antibodies; what features do they have in common
- IgA, IgD, IgE, IgG, IgM;
- neutralizes and agglutinates antigen
what are the roles of IgM in antigen disposal
- activates complement
what are the roles of IgG in antigen disposal
- activates complement
- opsonizes antigen
- enhances NK cell activity
what are the roles of IgE in antigen disposal
- binds to mast cells and basophils causing them to release histamine
describe neutralization
antibodies block the activity of a pathogen
describe agglutination
multiple pathogens are aggregated by antibody molecules
describe opsonization
pathogens bound by antibodies are more efficiently engulfed by phagocytes
describe complement activation
antibodies bound to pathogens activate the complement cascade resulting in lysis of cell
describe enhanced NK cell activity
abnormal body cells that are bound by antibodies are recognized by NK cells and are subsequently lysed
describe the roles of T cells in cell-mediated immunity
- helper T cells secrete cytokines that enhance activity of B cells and other T cells as well as enhance activity of macrophages and NK cells
- cytotoxic T cells kill virus-infected, abnormal, and bacteria cells including suppressor T cells which secrete cytokines that suppress activity of B cells and other T cells
- MHC molecules are unique to self (Class I and II) and T cells only recognize antigen when its associate with the MHC
describe antigen presentation
MHC molecules binding antigen within the cell and transporting antigen to the surface where it can be recognized by T cells
what is the main difference b/w cytotoxic and helper T cells
killing (cytotoxic) vs not killing (helper) antigen presenting cell
what are the types of immunization
active and passive
describe active immunity
- long-term immunity
- depends on immunized person’s immune system mounting a response
describe passive immunity
- short-term immunity
- ready-made antibodies introduce into person; the person’s B cells don’t make antibodies
describe how immunization works
- inactivated microorganism or harmless components of pathogen are part of immunization mechanism
- leads to a slow and weak primary immune response which makes antibodies (not needed) and memory cells (needed)
- the natural exposure to pathogen leads to a fast and strong secondary immune response which makes antibodies (needed) and memory cells
describe plasma antibodies and RBC antigens in all 4 blood groups
A: anti-B and A antigen
B: anti-A and B antigen
AB: none and A&B antigens
O: anti-B&A and none
if a blood receiver has anti-A antibodies and gets blood from a type A donor:
-what blood type and antibodies is the recipient?
- what antigens does the donor have?
- will there be agglutination or not?
- type B
- A antigens
- agglutination occurs bc antibodies and anitgens stick together
