18 Immunology IV: Practical Aspects of Immunology (diagnostic tests, vaccines, etc.) Flashcards
What kind of test can be used to exploit the antibody-antigen interactions?
Serological assays (serology)
What’s the principle of serological assays?
Since the Ab-Ag interaction is highly specific, if you have one, you can use it to detect the other
Name a specific type of serological assay.
ELISA (Enzyme Linked Immunosorbent Assay)
What does the presence of antibodies in someone’s blood tell you? [i.e. What does a positive ELISA test tell you?] (3)
- Current active infection w/ microbe
- Previous infection w/ the same microbe, but pt has recovered
- Prev. vaccination w/ the same microbe
Why can a person who’s infected w/ a microbe still give a negative ELISA result?
If testing is done during the “window period” b/w first contact w/ microbe and time at which first antibodies appear
A negative ELISA result can mean…(2)
- you don’t have antibodies for the microbe
2. you’re testing too early (during “window period”)
T or F: ELISA tests can be used to detect antibodies OR antigens.
T
How can ELISA tests be used to detect antigens:
- Start w/ antibody
- Submerge in soln w/ suspected antigen > antibody “captures” antigen
- Use second (“detection”) antibody
Name a common diagnostic test that uses ELISA “antibody-capture” technology.
Pregnancy tests
Name a type of test that utilizes Ab-Ag interactions to test for the presence of specific bacteria. “Clumping” rxns b/w antibody+bacteria are being looked for in this test.
Agglutination Test
What 3 broad categories of external agents can be used to alter immune sys fn via external manipulation?
- Pharmaceuticals
- Nutrients
- Nutritional supplements
Two types of pharmaceuticals that can alter immune sys fn?
- Immunosuppressive drugs
2. Immunostimulatory drugs
What’s the main problem w/ pharmaceuticals that can alter immune sys fn?
Most of them act NON-SPECIFICALLY > unwanted side effects
How do immunosuppressive drugs work?
Inhibit cell-mediated immunity, either by blocking cell division (inc’l T-cells) or blocking synthesis of cytokines
How do immunostimulatory drugs work?
Stimulate production of lymphocytes in bone marrow
Deficiency in some nutrients ____ immune fn.
impairs
Most studied nutrients wrt the immune sys? (5)
- Zn
- Selenium
- Cu
- Vitamins
- folic acid
What specific vegetable has been associated w/ immune sys boosting?
Broccoli
What’s the problem w/ nutritional supplements?
Evidence for efficacy controversial
What is “Cold-fX” made of?
Extract of North American Ginseng
What’re Cold-fX’s claims?
- Stimulates macrophage production/activity
- Increased amts of cytokines
- Increased production of B-cells and higher levels of circulating IgG
Have studies showed evidence for Cold-fX’s benefits in boosting the immune system?
No
Should we “boost” or “maintain” our immune sys?
Maintain (live healthy)
How can we create a protective immune response against a microbe without having to go through a natural infection first?
By immunizing w/ VACCINES
What is the principle of vaccination?
Memory B and/or T-cells are produced > future exposure > rapid immune response > rapid elimination of microbe before disease occurs
What is PASSIVE immunization?
TEMPORARY, short-term immunity that results when a person receives pre-existing antibodies from someone else
Two examples of passive immunization? What does ea. involve?
- Immune globulin
>IgG purified and collected from many donors carrying immunoglobulins against many diff pathogens - Maternal antibodies
>IgG transferred from mom to fetus that gives partial protection against microbes for first 4-6 mths of live
Two examples of immune globulin passive immunization?
- Post-exposure prophylaxis (helps w/ recent exposures)
2. Intravenous Immune Globulin (“IVIG”) (helps w/ inds who have trouble producing their own antibodies)
What influences the scheduling of early childhood vaccinations?
The disappearance of maternal antibodies
Define “active immunization”
longer-term immunity due to a natural immune response following exposure to an antigen (eg. a microbe)
How can active immunization be achieved?
by using VACCINES
Define vaccine:
A microbe, or a part of a microbe, that by itself does not cause
disease, but instead produces humoral &/or cell-mediated immunity
Two major types of vaccines:
- Whole-cell vaccines
2. Sub-unit vaccines
Two types of whole-cell vaccines:
- Killed whole-cell vaccines
2. Live, attenuated whole-cell vaccines
What’re whole-cell vaccines composed of?
ENTIRE microbe and all its antigenic parts
What’re sub-unit vaccines?
Parts of the microbe that’re the most antigenic and/or needed to cause disease
What’s the risk of killed whole-cell vaccines?
Adverse rxns bc “toxic” bacterial components may still be present (e.g. LPS)
T or F: There’s a chance of getting a disease from killed whole-cell vaccines
F (the microbe is KILLED)
What’re live attenuated whole-cell vaccines?
Living microbes that’ve been weakened (“attenuated”)
How’re live, attenuated whole-cell vaccines made?
Microbe is continuously grown in lab until it accumulates mutations that REDUCE its ability to grow inside human host
What type of whole-cell vaccine results in life-long immunity?
Live, attenuated whole-cell vaccines
What type of whole-cell vaccine requires repeated immunizations?
Killed, whole-cell vaccines
Two probs w/ live, attenuated whole-cell vaccines?
- Slight risk of “back-mutation” to the original, non-attenuated microbe
- Immunocompromised inds are not advised to get them
Synonym for “Sub-unit” vaccines?
Acellular
What’s used to make sub-unit vaccines?
Ind, purified bacterial components (instead of whole cells) that give a strong immune rxns/are known to be req’d for disease
Give 3 e.g.’s of components used to make sub-unit vaccines:
- Capsular polysaccharide
- Pili
- Bacterial toxins
Probs w/ sub-unit vaccines?
- Less likely to produce cell-mediated immunity
2. Less likely to give life-long immunity (booster shots required)
What type of vaccine is the tetanus vaccine?
Sub-unity vaccine
What’re adjuvants?
Non-antigenic components in vaccines that ENHANCE the immune response to the antigen
What type of vaccines are adjuvants esp. useful for?
Sub-unit vaccines
Possible side-effect of adjuvants?
Mild, adverse rxns at site of injection
What is the most important strategy wrt vaccinations?
TIMING of vaccination
What can occur if a vaccine is given to an infant too early while his maternal antibodies are still present?
The maternal antibodies will interfere w/ the immune response to the vaccine if the first dose is given too early
What is “herd immunity”?
Protection achieved by being part of a lger gp that includes many immunized members
T or F: It’s necessary to vaccinate 100% of the pop in order to prevent the spread of infectious diseases.
F
this is due to “herd immunity”
T or F: At least 90% of the pop MUST be vaccinated before herd immunity is achieved.
F
It always varies depending on many factors (such as effectiveness of the vaccine, contagiousness of microbe, etc.)
T or F: Side effects tend to be more of a concern w/ older vaccines compared to current ones.
T
What was the prob w/ the older oral poliovirus vaccine?
It was a live, attenuated virus
What’re most side effects of vaccines due to?
The ADDITIVES included in the vaccine formulation (not the antigen itself)
T or F: There’s evidence to support links between vaccine usage and serious complications (eg. autism, etc.).
F
Do vaccines actually work?
Yes (huge drop in disease cases in postvaccine era)
List some challenges associated w/ vaccine development (7):
- Finding the right microbial antigen > should give protective immunity and avoid adverse rxn
- Getting better life-long immunity and reducing the need for “boosters”
- Increasing vaccine stability under adverse conditions (e.g. those used in 3rd world settings)
- Improving delivery systems
- Increasing % of ppl vaccinated
- Improving public perception/awareness of vaccine benefits
- Maintaining high vaccination rates for “old” diseases
What’s the problem w/ “bundling” ind vaccines into one fmlation?
More components = weaker immune response to ea. ind component
