immune system lecture draft

chapter 21

2 different main types of immune defense

innate (nonspecific) and adaptive

innate definition

to be born with an ability

2 innate (nonspecific) defense categories

(general defensive measures), surface and internal

surface defenses

first line of innate defense (skin and mucous membranes)

how does acidity relate to immune function?

higher acidity kills bacteria, pathogens, and other immune threats

internal defenses

second line of innate defense (phagocytes, natural killer [NK] cells, and inflammation)

phagocytes of internal defenses

neutrophils, monocytes, and macrophages (some have ability to lyse things)

natural killer (NK) cells

kill virus-infected and cancerous cells

what do NK cells induce

apoptosis (programmed cell death)

apoptosis real-world association example

tadpoles losing their tails as they develop

what are NK cells similar to from the adaptive defenses

cytotoxic T-cells

how does inflammation play a part in internal defenses?

isolates infection to prevent spread and alerts immune system

vasodilation role in inflammation

allows delivery of cells to injury to aid recovery via widening of blood vessels

inflammatory chemicals

histamine, kinins, prostagladins, complement, and cytokines

phagocyte mobilization ***must know

delivery of neutrophils and macrophages

4 key steps of phagocyte mobilization

1.leukocytosis (4-5x increase in neutrophil count after injury)

2.margination (neutrophils cling to cap walls)

3.diapedesis (neutrophils flatten and move thru cracks)

4.positive chemotaxis (phagocytes sniff out chemical signal)

antimicrobial proteins prod during inflammation

interferons (IFNs) and complement (molecule group)

functions of antimicrobial proteins

directly attack or inhibit microbe prod

interferons (IFNs)

released by virus-infected cells, protect nearby cells

complement

20+ plasma proteins that lyse microbes and amplify response

what causes a fever

pyrogens which are released by leukocytes and macrophages

effects of a fever

interferes with microbe reprod, increases metabolic rate, and hoarding zinc and iron (nutrients) from the microbes

adaptive (specific) defenses

act against recognizable invaders

two types of adaptive defenses

humoral and cell-mediated immunity

unique ability of adaptive defenses

memory of invaders

humoral (antibody-mediated) immunity

targets foreign bodies

cell-mediated immunity

targets infected cells affected by viruses, bacteria, parasites, and cancer

virus

infectious agent that multiplies by inhabiting a living host’s cells

antigens ***TQ

molecules that trigger immune response and thus stimulating antibody production

antibodies ***TQ

defensive proteins (immunoglobulins) produced in response to antigen

complete antigens

immunogenic (causes immune response) and reactive

immunogenic antigen

only causes immune response

reactive antigen

able to react/bind to antibodies

incomplete antigens

an antigen that is powerless alone, but can combine with other self-made molecules to generate response

antigenic determinants

immunogenic part of an antigen

immunogenic definition

ability to cause an immune response

self-antigens

2 main classes of major histocompatibility complex (MHX) proteins found on own cells

class I MHCs

found on most body cell surfaces (except rbcs)

class II MHCs

only found on specialized immune system cells

origin site of rbc and thymus

red bone marrow

where do b cells mature

red bone marrow

where do t cells mature

thymus

life cycle of B and T lymphocytes

born in bone marrow, b cell stays to mature, t cell moves to thymus to mature, naive cells travel to secondary lymphoid organs (nodes, spleen) and might eventually encounter foreign antigens that activate them, clonal selection leads to proliferation (creation of more lymphocytes)

***review positive/negative selection in life cycle of B and T lymphocytes

***

immunocompetence

lymphocyte ability to recognize and bind to an antigen

self-tolerance

lymphocyte ability to ignore self-made antigens

antigen-presenting cells (APCs)

phagocytize antigens and present fragments to T cells

**review apcs slide

humoral immunity

B cells and antibodies fight specific invaders

steps in humoral immunity

naive B cells bind to antigen, become active and antigen specific, clonal selection duplicates those active B cells, most become plasma cells, some become memory cells

plasma cells

effector cells that produce antibody

effector cell

a cell that responds to stimuli and brings about change

memory cells

long living cells that provide immunological memory

2 immunological memory phases

primary response and secondary response

**review primary/secondary response

active immunity

B cells make own antibody and memory cells from pathogen or vaccine exposure

how do vaccines grant active immunity

they have antigenic determinants, mRNA, toxoids, etc.

passive immunity

antibody received from an outside source

different sources of passive immunity

placenta, mother’s milk, or injection (ex. antivenin/antivenom or tetanus antibody)

antibodies

proteins of the immune system (immunoglobulins)

5 classes of antibodies

IgM, IgA, IgD, IgG, IgE

IgM

1st class released during primary response (complement fixation/activation, agglutination)

**agglutination

particles clumping together in the presence of antibody or complement

IgA

common in body secretions (sweat, intestinal juice, milk)

IgD

common on B cell surfaces as antigen receptor

IgG

most abundant antibody in plasma, complement fixation/activation

main antibody of primary and secondary responses

IgG

IgE

triggers histamine release, inflammatory response, allergies

**antibody funtions

neutralization, agglutination, precipitation (converting state of matter to make it easier to phagocytize), complement activation

what effect do antibody functions lead to/enhance?

phagocytosis, inflammation, and cell lysis

monoclonal antibodies

single type of antibody grown in lab from descendants of a single cell, specific to one antigenic determinant

what can monoclonal antibodies be used for?

treating cancer, autoimmune diseases, and other diseases (not useful for treating rapidly evolving viruses)

cell-mediated immunity

involves different kinds of T cells attacking defective cells

what do CD4 cells become?

most become helper T cells, some become regulatory T cells

what do CD8 cells become?

cytoxic t cells

**class I MHC proteins

found on all cells except RBCs

**class II MHC proteins

found only on antigen-presenting cells (APCs)

boy in a bubble disease

severe combined immunodeficiency syndromes (SCIDS)