Help with NBME Q

[foodie05]

---

Members don't see this ad.

Hi guys, had a question while studying:

Several children who are members of a family with a hereditary deficiency of C6 have Neisseria meningitidis-induced sepsis. Incubation of antibody-coated meningitidis with plasma from the affected children is most likely to produce which of the following findings?
(bacterial killing) (generation of anaphylatoxins)
a) decreased/decreased
b) decreased/normal
c) normal/decreased
d) normal/normal

I thought it would be b) because C3a and C5a are mediated in anaphylaxis, but some people say the answer is A. Can anyone explain?

Thanks!

 

[majik1213]

i think you are absolutely right in picking B. here is my solution (which probably won't offer more insight than you have in this situation):

bacterial killing requires a working MAC complex, which because of the C6 deficiency, does not form. You can rule out answer choices C and D.

the antibody-coating means that the particular pathway involved is the classic pathway, not the lectin or alternative pathway. The classic pathway makes anaphylaxins C3a and c5a prior to the MAC formation; therefore, you should expect normal generation of anaphylatoxins.

I'm making the assumption that anaphylaxins = anaphylatoxins in this problem, because to be honest I never heard of the term, anaphylatoxin, but I guess they're the same. If not, then my solution may be questionable.

 

[turkeyjerky]

i think you are absolutely right in picking B. here is my solution (which probably won't offer more insight than you have in this situation):

bacterial killing requires a working MAC complex, which because of the C6 deficiency, does not form. You can rule out answer choices C and D.

the antibody-coating means that the particular pathway involved is the classic pathway, not the lectin or alternative pathway. The classic pathway makes anaphylaxins C3a and c5a prior to the MAC formation; therefore, you should expect normal generation of anaphylatoxins.

I'm making the assumption that anaphylaxins = anaphylatoxins in this problem, because to be honest I never heard of the term, anaphylatoxin, but I guess they're the same. If not, then my solution may be questionable.

Agree with this. Who told you A was correct? I mean was it on the answer key, or just a another student.