[absolutjag9]

Question 1:
When a person has Measles, antibodies are produced which provide protection against Measles virus but no other viruses. What is the role of Measles virus proteins in creating this specificity?

A. Determine which clones of lymphocytes with antigen-specific receptors will proliferate.
B. Prevent negative selection of immature T lymphocytes with measles-specific receptors.
C. Promote negative selection of immature B lymphocytes with self-reactive receptors.
D. Determine which V/D/J DNA segments are used to assemble antibody genes.
E. Specify nucleotides added at DNA splice joints during immunoglobulin gene assembly.

Question 2:
A child who has had one previous immunization against tetanus is given the second immunization in the recommended series, three months later. In what way would you expect the immune response to the second immunization to differ most significantly from the response to the first?

A. The second response will be slower, but more prolonged.
B. The second response will be larger, but shorter.
C. The second response will produce more antibody, but after a longer lag.
D. The second response will be primarily cell-mediated, the first primarily antibody-mediated.
E. The second response will produce a higher ratio of IgG to IgM.*

Question 3:
A patient has a respiratory allergy to oak pollen and asks about the possibility of desensitization by immunization, such as is possible for bee-sting allergy. You tell the patient that this mode of therapy works less well against respiratory allergies than against insect-venom allergies. What creates this difference in effectiveness?

A. Pollen antigen for desensitization is not available.
B. Insect venoms are more immunogenic than pollen.
C. IgA in nasal secretions binds pollen, preventing binding of IgG.*
D. Mast cell degranulation plays little role in respiratory allergies.
E. IgG blocking antibody has less access to pollen than to insect venom.

Question 4:
Test reaction Result
Patient erythrocytes + anti-A serum
No Agglutination
Patient erythrocytes + anti-B serum
Agglutination
Patient erythrocytes + anti-Rh0(D) serum
No Agglutination
Patient serum + Type A erythrocytes
Agglutination
Patient serum + Type B erythrocytes
No agglutination
Patient serum + Type O erythrocytes
No agglutination

What is the patient's blood type?
A) A, Rh positive
B) A, Rh negative
C) B, Rh positive
D) B, Rh negative
E) AB, Rh negative

 

[drmodi44]

1st D. Determine which V/D/J DNA segments are used to assemble antibody genes.
2nd E. The second response will produce a higher ratio of IgG to IgM
3rd E. IgG blocking antibody has less access to pollen than to insect venom. not sure...:notsure:
4th D) B, Rh negative

 

[drsue]

2 i'll go with E
4 i'll go with D
3 i'll go with c

 

[Seetal]

hmm

i tot it was:

1.A
2.D
3.D
4.A

what am i doing wrong here? can u pls tell us the answer. it seems tough.

 

[Bella]

1-A
2-E
3-C
4-D
?????????? What say??

 

[5dns]

my ans

1.a
2.e
3.c
4.d

 

[usmle100]

please provide explanations...

 

[Peewee]

1. When a person has Measles, antibodies are produced which provide protection against Measles virus but no other viruses. What is the role of Measles virus proteins in creating this specificity?

A. Determine which clones of lymphocytes with antigen-specific receptors will proliferate.
B. Prevent negative selection of immature T lymphocytes with measles-specific receptors.
C. Promote negative selection of immature B lymphocytes with self-reactive receptors.
D. Determine which V/D/J DNA segments are used to assemble antibody genes.
E. Specify nucleotides added at DNA splice joints during immunoglobulin gene assembly.

Cell Mediated Humoral
------------- --------
Virus Bacteria
Fungus
Mycobacterium
Protozoa
Parasite
Neoplasms

Since measles is a virus it will be cell mediated. That means you should be looking for something with T cell / MP

E- just doesn't make sense for a lot of reasons

D- You won't need to worry about what builds an antibody

C- Promote negative selection by B lymphoctyes? I believe negative selection is only done on the T-cells, so that can't be the answer

B- Prevent negative selection by T lymphocytes? Negative selection is asking you- "does it attack you? if its a NO, then it passes and can become T-helper cell). Preventing negative selection will cause T cells to attack the body. So this can't be the answer since your immune is only attacking the measles. Can't be this answer

A- Determining which lymphocytes will proliferate. The body has hundreds of thousands of antibodies floating around. The virus and antibodies run into each other and as luck would have it, there becomes a correct match. The body then says "OK, I have a match to this invader, its time to make more/proliferate this antibody to fight off this infection."

So, A, is the correct answer

Question 2:
A child who has had one previous immunization against tetanus is given the second immunization in the recommended series, three months later. In what way would you expect the immune response to the second immunization to differ most significantly from the response to the first?

A. The second response will be slower, but more prolonged.
B. The second response will be larger, but shorter.
C. The second response will produce more antibody, but after a longer lag.
D. The second response will be primarily cell-mediated, the first primarily antibody-mediated.
E. The second response will produce a higher ratio of IgG to IgM.*

When you are infected with a virus/toxoid/what ever else you can come up with, the body ALWAYS produces IgM first. The problem is the IgM doesn't have any memory, IgG is your memory.

The first time you were injected with Tetanus, IgM came first. The body then said, we got rid of the virus but lets keep a couple IgG around just in case that tetanus ever decides to come back. The next time you inject tetanus in the body, IgM is first to arrive but the IgG says "hey, I remember this tetanus guy, we were brought here to serve and protect, lets attack him, so more IgG come to fight off the virus."

Since you body has now encountered that tetnus more than once, it says, "I think we should keep more IgG around since we constantly have this unwanted visitor around". Thus you will have E. The second response will produce a higher ratio of IgG to IgM.*

Answer is E

Question 4:
Test reaction Result
Patient erythrocytes + anti-A serum
No Agglutination
Patient erythrocytes + anti-B serum
Agglutination
Patient erythrocytes + anti-Rh0(D) serum
No Agglutination
Patient serum + Type A erythrocytes
Agglutination
Patient serum + Type B erythrocytes
No agglutination
Patient serum + Type O erythrocytes
No agglutination

What is the patient's blood type?
A) A, Rh positive
B) A, Rh negative
C) B, Rh positive
D) B, Rh negative
E) AB, Rh negative

i)Patients RBC is given a drop of anti-A and doesn't produce clumping- so that must means there is no A in the patients RBC.

ii) Patients RBC is given a drop of anti-B and it does produced clumping so that must mean this IS B in the patients RBC

iii) Patient RBC is given a drop of Anti-Rh, and it doesn't clump so there is no Rh factor in his blood.

The other 3 tests are just figuring it out, only in a different test, it tells you the same thing. So looking at i, ii, iii- get your white board and write down what we came up with- B Rh negative

Answer is D

Question 3:
A patient has a respiratory allergy to oak pollen and asks about the possibility of desensitization by immunization, such as is possible for bee-sting allergy. You tell the patient that this mode of therapy works less well against respiratory allergies than against insect-venom allergies. What creates this difference in effectiveness?

A. Pollen antigen for desensitization is not available.
B. Insect venoms are more immunogenic than pollen.
C. IgA in nasal secretions binds pollen, preventing binding of IgG.*
D. Mast cell degranulation plays little role in respiratory allergies.
E. IgG blocking antibody has less access to pollen than to insect venom.

Storming, don't want to lose my internet, will try to explain this after it passes

Hope what I said makes sense