A 12 month old

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A 12 month old

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drduck
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06/15/07 - 10:03 AM

A 12 month old child with a 6 month H/O repeated infections presents with a lung infection and elevated number of neurophils in peripheral blood. Aspiration of the lung abcess shows accumalation of neutrophils. Labratory studies demonstrate that his neutrophil phagocytosis and kill organisms normally in the presence of normal human serum(but not in patients serum). They migrate normally in a chemotaxis assay. Which of the following is the most likely cause for the increased susceptibility to infection?

A-deficiency of integrins
B-neutrophil microtubular protein defect
C-immunoglobulin deficiency
D-defective neutrophil H2O2 generation
E-deficiency of selectins

peraspera
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06/15/07 - 10:56 AM

doc179
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06/15/07 - 11:00 AM

silver
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06/15/07 - 11:18 AM

C-immunoglobulin deficiency

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faraym
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06/15/07 - 11:30 AM

D?
Becoz they can do everything except kill. They are fine in normal serum .

Hope Iam right. confused

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jean robert
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06/15/07 - 11:54 AM

A

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new_n_lost
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06/15/07 - 01:59 PM

D-defective neutrophil H2O2 generation ???

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silver
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06/15/07 - 02:14 PM

new_n_lost wrote:
D-defective neutrophil H2O2 generation ???

can you plz explain why?

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doc179
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06/15/07 - 02:16 PM

no its not D, see his neutrophils opsonize properly in normal serum and not in patient serum, that means the patient either lacks IgG or C3b, since C3b is not a choice, the answer is C.

that means normal serum has IgG and this guy does not. if the answer was D then even in normal serum the neutrophils wouldn't behave normal.

silver
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06/15/07 - 02:25 PM

#10

i think this ques. is dealing with the concept of opsonization. in direct opsonization the antibody binds to the particulate matter and then the entire complex gets phagocytosed.

in this patient, the reason for the accumalation of neutrophils is that there are no immunoglobulins to bind the particulate matter and then signal the neutrophils to come and phagocytose. so they're functioning properly, they come to where the particulate matter is but find no immunoglobulin that signals them to begin their phagocytosis.

this is what i understood and why i went with choice C.

Edited by silver on 06/15/07 - 02:32 PM

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new_n_lost
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06/15/07 - 02:32 PM

#11

doc179 wrote:
no its not D, see his neutrophils opsonize properly in normal serum and not in patient serum, that means the patient either lacks IgG or C3b, since C3b is not a choice, the answer is C.

that means normal serum has IgG and this guy does not. if the answer was D then even in normal serum the neutrophils wouldn't behave normal.

Ooppps Yup right on that Count .

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doc179
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06/15/07 - 02:34 PM

#12

ssrpk wrote:
don't remember much of basics, although C seems reasonable but how would you rule out A or E

well there is neutrophil accumulation, that means there was margination and emigration, that means integrins and selectins are there and working.

peraspera
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06/15/07 - 02:39 PM

#13

A 12 month old child with a 6 month H/O repeated infections .
He is 12 mo, so mother's immunoglobulins are gone and no immunoglbs.
the rest of explanation I do agree with silver.

C
nod

faraym
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06/15/07 - 02:56 PM

#14

whats the ans drduck?

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drduck
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06/15/07 - 10:18 PM

#15

these Q seems easy and they are actually....but need some extra time and attention......even i went for D...missed the line that its action is normal in control sera...

the answer is C........
problem was in the sera.....of the patient wink

Edited by drduck on 06/16/07 - 12:18 AM

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