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Specific Immunity
MIC 205 Exam 3
Question | Answer |
---|---|
What is an antigen? | A chemical/molecule capable of stimulating the immune response |
What makes a good antigen? | proteins (large molecules that don’t change shape) |
What is an epitope or antigenic determinant? | specific regions of an antigen that stimulate their response |
What is a hapten? | small molecule that is antigenic because it is attached to an antigen |
What are the main characteristics of the specific immune response? | acquired, develops over time; specialized; diverse; has memory capabilities; prevents infection; discriminatory between self/non-self; self-limited |
How does specific immunity differ from the non-specific immune response? | response is antigen dependent, there is a lag time between exposure and maximal response, antigen specific, exposure results in immunologic memory |
How do lymphocytes recognize antigens? | membrane antigen receptors |
What is the difference between T and B cell receptors? | T cells antigen receptor is composed of two chains; B cell antigen receptor is composed of four chains |
How are we born with the capability of responding to every antigen in the universe? | billions of different antigen receptors are created by gene rearrangement and point mutations during development |
Why don’t we form antibodies to our own antigens? | we have developed tolerance to them |
What is the difference between humoral and cell-mediated immunity? | humoral-uses antibodies; cell mediated immunity-no antibodies |
What cells are responsible for each? | humoral-B cells; cell mediated immunity-T cells |
What is the Major Histocompatibility Complex? | a cluster of genes, located on each copy of chromosome 6 in humans, that codes for membrane-bound glycoproteins called major histocompatibility antigens |
What cells produce MHC I proteins? | all nucleated cells |
What cells produce MHC II proteins? | macrophages, B cells, and dendritic cells |
Which lymphocytes respond to MHC I proteins? | cytotoxic T cells |
Which cells respond to MHC II proteins? | CD4 helper T cells |
What is the difference between TH1 and TH2 CD4 cells? | TH1-produce cytokines that stimulate macrophages to kill intracellular organisms, stimulate CD8 cells; TH2-stimulate B cells to become plasma cells to produce antibodies |
Which cell is responsible for an inflammatory response? | TH1 CD4 cells |
Which cell is responsible for stimulating B cells to form antibodies? | TH2 CD4 cells |
Explain why parasite infections increase a person’s chance of having the more dangerous lepromatous form of leprosy. | Lepromatous leprosy initiates a TH2 response (antibody response) that is ineffective against parasites |
What causes the tubercles that we see with infection by Mycobacterium tuberculosis? | macrophages fused together surrounded by TH1 cells stimulated by cytokines |
What causes the lesions called gummas seen in tertiary syphilis? | caused by the body trying to rid itself of the spirochete |
Would antibiotics be helpful in treating gummas? | yes |
What is a superantigen? | antigens that don’t have to be processed (phagocytized) by an antigen presenting cell to be recognized by a CD4 cell |
What do superantigens do to a host? | results in systemic toxicity and suppression of normal, specific, adaptive response |
Give some examples of organisms that can produce superantigens. | Staphylococcus & Mycoplasma |
What is an antibody? | protein made against antigen |
In which portion of the blood are antibodies found? | gamma globulin portion of blood |
What is the role of IgA? | neutralization and agglutination |
What is the role of IgE? | triggers release of antiparasitic molecules and histamines |
What is the role of IgM? | complement activation, neutralization, agglutination |
What is the role of IgG? | complement activation, neutralization, opsonization, production of hydrogen peroxide, agglutination, ADCC, crosses placenta to protect fetus |
Which is found in the greatest amounts in the plasma? | IgG |
Which is the largest antibody? | IgM |
Which one can’t cross the placenta? | IgM |
Describe the sequence of events that lead to antibody production. | Macrophage engulfs/digests antigen; Macrophage presents antigen & MHC II on its membrane; CD4 cell reads it and responds as a TH2 cell; TH2 cell stimulates B cells to become plasma cells and secrete antibodies |
What role do macrophages and T helper cells play? | Macrophages engulf/digest antigens and present them the antigens; T helper cells (CD4 cells) read the antigens and respond |
What is a plasma cell? | type of white blood cell that produces antibodies |
Name 5 ways antibodies protect a host from foreign antigens. | neutralize toxins, prevent virus attachment to host cells, fix complement (cell lysis), opsonization (coding), begin destruction of NK cells, catalyze production of hydrogen peroxide |
What is immunologic memory? | the capacity of the body’s immune system to remember an encounter with an antigen due to the activation of B or T cells having specificity for the antigen and to react more swiftly to the antigen by means of these activated cells in a later encounter |
Which antibody is responsible for the secondary antibody response? | IgG |
What is antigenic variation? | antigens have the ability to change through mutations |
What is antigenic variation’s effect on the immune response? | Memory T & B cells cannot recognize new antigenic type; delays response |
Explain naturally acquired active immunity. | occurs naturally by living; responds by continually making antibodies |
Explain naturally acquired passive immunity. | mother transfers her antibodies to fetus across placenta or to infant in milk |
Explain artificially acquired passive immunity. | gamma globulin (antiserum); comes from people or animals that have had the disease; immediate protection (last only about 3 weeks) |
Explain artificially acquired active immunity. | vaccination |
What is a vaccine? | suspension of organisms or parts of organisms used to induce artificially acquired, active immunity |
What is the purpose of vaccination? | to develop immunity and to hopefully eradicate diseases; herd immunity |
What is herd immunity? | occurs when the vaccination of a significant portion of a population (herd) provides a measure of protection for individuals who have not developed immunity |
What is seroconversion? | the development of detectable specific antibodies to microorganisms in the blood serum as a result of infection or immunization |
What is a titer? | the highest dilution of blood serum giving a positive reaction during titration |
How does one get infected with the polio virus? | fecal-oral route |
What are the symptoms of polio? | most people have no symptoms; flu-like symptoms; paralysis |
What is the difference between the Salk and Sabin vaccine? | Salk-inactivated, kill vaccine, injected, need boosters, stable (can’t cause disease); Sabin-live, attenuated vaccine, oral vaccine, no boosters, unstable (can cause disease) |
Which is used in the United States? Why? | The Salk vaccine because it can’t cause the disease and we have the means to store it properly and have clean needles |
What are monoclonal antibodies? | antibodies that are the same because they are made by identical immune cells that are all clones of myeloma cells |
What kind of cells produces monoclonal antibodies? | myeloma cells (cancerous cells) |
Why are these cells immortal? | because immortal cancerous cells are combined with normal B cells |
Why are monoclonal antibodies so useful? | because they live indefinitely and produce large amounts of very specific, uniform antibodies |
How are monoclonal antibodies being used? | treat tumors, blood typing, identify Chlamydia & Streptococcus, pregnancy tests, prevent transplanted tissues rejection, antibodies for passive immunization |