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Vocababble: Microbiology and Immunology II

Immune system is divided into a more primitive innate immune system, and acquired or adaptive immune system of vertebrates, the latter of which is further divided into humoral and cellular components.

B-cells = make antibodies against antigens, produced in bone marrow, two main types: plasma B cell and memory B cell

plasma B-cell = large B cells that have been exposed to antigen and produce/secrete antibodies, which assist in the destruction of microbes by binding to them and making them easier targets for phagocytes and activation of the complement system. They are sometimes referred to as antibody factories. An electron micrograph of these cells reveals large amounts of rough endoplasmic reticulum in the cytoplasm, where antibody is synthesized.

complement system = a biochemical cascade which helps clear pathogens from an organism
--part of the larger immune system that is not adaptable and does not change
--Can be recruited and brought into action by the adaptive immune system
-- = a number of small proteins found in the blood, normally circulating as inactive zymogens
--When stimulated by triggers, proteases in the system cleave specific proteins to release cytokines and initiate an amplifying cascade of further cleavages
--end result of this activation cascade is massive amplification of the response and activation of the cell-killing membrane attack complex
--Over 20 proteins and protein fragments make up the complement system, including serum proteins, serosal proteins, and cell membrane receptors. These proteins are synthesized mainly in the liver, and they account for about 5% of the globulin fraction of blood serum.
--THREE PATHWAYS activate the complement system: the classical complement pathway, the alternative complement pathway, and the mannose-binding lectin pathway.

memory B cell
--formed from activated B cells specific to antigen encountered during primary immune response
--live for a long time (in the spleen?)
--respond quickly following a second exposure to the same antigen.
--have a unique paratope (the sequence of amino acids that binds to the epitope on an antigen).

--belong to a group of white blood cells known as lymphocytes
--central role in cell-mediated immunity
--distinguished from B cells and NK cells by presence of a special receptor on their cell surface called the T cell receptor (TCR)
--T stands for thymus, since it is the principal organ in the T cell's development

memory T cell aka T lymphocyte
--recognizes foreign invaders that were encountered during a prior infection or vaccination
--second encounter-->reproduce to mount a faster and stronger immune response than the first time

humoral immunity
--Humoral Immune Response (HIR)
--mediated by secreted antibodies produced in the cells of the B lymphocyte lineage (B cell)
--Secreted antibodies bind to antigens on the surfaces of invading microbes, flags them for destruction
--involves substances found in the humours, or body fluids.
--accessory processes: Th2 activation and cytokine production, germinal center formation and isotype switching, affinity maturation and memory cell generation
--also effector functions of antibody, which include pathogen and toxin neutralization, classical complement activation, and opsonin promotion of phagocytosis and pathogen elimination.

cell-mediated immune response = T-cell mediated immunity
--does not involve antibodies
--involves the activation of macrophages, natural killer cells (NK), antigen-specific cytotoxic T-lymphocytes, and release of cytokines
--activates antigen-specific cytotoxic T-lymphocytes that are able to induce apoptosis in body cells displaying epitopes of foreign antigen on their surface, such as virus-infected cells, cells with intracellular bacteria, and cancer cells displaying tumor antigens
--activating macrophages and natural killer cells, enabling them to destroy intracellular pathogens
--stim cytokines to influence the function of other cells involved in adaptive and innate immune responses
--Cell-mediated immunity is directed primarily at microbes that survive in phagocytes and microbes that infect non-phagocytic cells
--most effective in removing virus-infected cells, but also participates in defending against fungi, protozoans, cancers, and intracellular bacteria
--plays a major role in transplant rejection.

antigen = immunogen
--a molecule that sometimes stimulates an immune response
--usually proteins or polysaccharides (coats, capsules, cell walls, flagella, fimbrae, and toxins) of bacteria, viruses, and other microorganisms
--Lipids and nucleic acids are antigenic only when combined with proteins and polysaccharides
--Non-microbial exogenous (non-self) antigens can include pollen, egg white, and proteins from transplanted tissues and organs or on the surface of transfused blood cells.

immunoglobin = antibody
--proteins found in blood or other fluids
--used by the immune system to identify and neutralize foreign objects
--typically made of basic structural units - each with two large heavy chains and two small light chains
--Five different antibody isotypes are known in mammals
--general structure of all antibodies is very similar
--a small region at the tip of the protein is extremely variable: the hypervariable region
--each can bind to a different antigen
--The unique part of the antigen recognized by an antibody is called an epitope
--epitopes bind with their antibody in a highly specific interaction, called induced fit

"self" antigen = The antigens of an organisms own cells and cell products are self antigens to the immune system of that organisn. Clones of immune cells reactive with self antigens are normally eliminated.

toxoid = a part of a toxin that is not toxic but has antigens on it to help the body generate specific antibodies and remember how to make them

vancomycin -- last ditch antibiotic used for many microbes that are resistant to just about everything else. Beware if you have kidney disease, problems with your hearing, or a chronic intestinal condition such as inflammatory bowel disease, Crohn's disease, or ulcerative colitis. Vancomycin can cause temporary or permanent hearing loss. Stop taking this medication and call your doctor at once if you have any hearing problems or ringing in your ears.

clavulanic acid = a beta-lactamase inhibitor. Some bacteria produce beta-lactamase which allows them to take apart penicillins, so if you give them c. acid with the penicillin you might get more action out of the antibiotic

LPS = lipopolysaccharide = endoxotin, present in gram negative bacteria, causes fever etc. Listeria is the only gram positive bacteria that has it.

--a soluble protein excreted by a microorganism, including bacteria, fungi, algae, and protozoa
--Both gram negative and gram positive bacteria produce exotoxins
--may be secreted or released during lysis of the cell.
--Most exotoxins can be destroyed by heating
--may work locally or produce systemic effects
--Well known exotoxins: botulinum toxin, Corynebacterium diphtheriae exotoxin
--Exotoxins are susceptible to antibodies produced by the immune system
--many exotoxins are so toxic that they may be fatal to the host before the immune system has a chance to mount defenses against it

adhesins = pilli etc that let bacteria stick to host tissues

invasins = enzymes that break through cell membranes so bacteria can get in

leukotoxins = things that are poisonous to WBC's

leukocidins = things that kill WBC's


( 1 comment — Leave a comment )
Mar. 26th, 2008 08:06 pm (UTC)
I think this is for people with a medical predilection -- which I tend to have as a once-upon-a-time medical transcriber.

Muchas gracias,

( 1 comment — Leave a comment )



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