CVID vs Agammalobulinemia - USMLE Forums
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Old 04-08-2012
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Immunology CVID vs Agammalobulinemia

In Kaplan Pathology, it states that X-linked agammaglobulinemia of Bruton is due to a failure to produce mature B and plasma cells. It then says that Common variable immunodeficiency (CVID) is characterized by a B-cell maturation defect (cannot differentiate to plasma cells).

In pathoma, Dr.Sattar states that Agammaglobulinemia of Bruton is due to inability of B cells to mature into Plasma cells. For CVID he just says its "common variable immunodeficiency" and results in hypogammaglobulinemia.


My confusion: Do both of them have the same defect ... unable to mature B cells into plasma cells .. so both the diseases have low number of plasma cells (hence hypogammaglobulinemia) but a normal number of B cells ? .. or does Agammaglobulinemia of Bruton have both B cell and Plasma cell deficiency whereas CVID only has a plasma cell deficiency (inability to mature B cells to plasma cells) ??


Sorry if this is confusing. No other way to put it
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Old 04-09-2012
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Remember- XLA is B-cell maturation disorder, whereas CVID is undefined B-cell dysfunction, resulting from failure at last stage of B cell differentiation into plasma cells.

In XLA patients:
- Pre B-lymphocytes are commonly found, but very few of these immature B-cells can transform into mature B-lymphocytes due to lack of BtK enzyme.

- It X-linked recessive and occurs in boys during childhood

- Circulating B cells and plasma cells are absent.

In CVID:

- decreased serum IgG and IgA, occasional IgM deficiency subset of patients manifest with T cell deficiency

- Only a minority of CVID patients (5%-10%) show very low B-cell counts (<1% of peripheral blood leukocytes)

- Disease can manifest any time ranging from childhood, adolescence to adult age - 20-40 yrs.

Hope I explained it better than Kaplan or Sattan
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Old 04-09-2012
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i think the difference is the stage of development to a plasma cell in which these two differ.

i mean, Bruton's is lack of the brutons kinase thingy and so your B-cell doesnt even make it to being a mature B-cell. remember, in this disease the maturation of this cell line stops at Pre-B cells (differentiated heavy chain, undifferentiated light chain) <-- thats highly tested.
in CVID, i think the defect is later down the line, somewhere around B-cell differentiation into certain Ig-producing plasma cells. such as, normal IgM but decreased in G, A, E immunoglobulins.

i dont think CVID is highly tested. but Bruton's surely is.
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Old 04-09-2012
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Quote:
Originally Posted by Dr.NickRiviera View Post
i think the difference is the stage of development to a plasma cell in which these two differ.

i mean, Bruton's is lack of the brutons kinase thingy and so your B-cell doesnt even make it to being a mature B-cell. remember, in this disease the maturation of this cell line stops at Pre-B cells (differentiated heavy chain, undifferentiated light chain) <-- thats highly tested.
in CVID, i think the defect is later down the line, somewhere around B-cell differentiation into certain Ig-producing plasma cells. such as, normal IgM but decreased in G, A, E immunoglobulins.

i dont think CVID is highly tested. but Bruton's surely is.
oops, sorry for being redundant.

"i dont think CVID is highly tested. but Bruton's surely is"
what do you mean by "highly tested" ?

What is the reason of normal IgM in CVID ?
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Old 04-09-2012
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Quote:
Originally Posted by slumdog View Post
oops, sorry for being redundant.

"i dont think CVID is highly tested. but Bruton's surely is"
what do you mean by "highly tested" ?

What is the reason of normal IgM in CVID ?
not highly tested on the step1
its not as high yield as brutons is

normal IgM because its the default Ig. you dont need class switching for IgM or IgD. but G, A, E require class switching via B-cell interaction with T-cells.
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Well, I did not know it.

Though the reason that you mention does not explain, why IgM is normal only in half of the CVID cases.
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Thanks guys. It helped a lot.

So basically-

XLA - Pre-B lymphocytes are increased because there's a maturation defect.

CVID - Cannot differentiate into plasma cells so you have low immunoglobulins but normal or decreased B cells.
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Old 07-13-2012
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Thanks for those nice information guys,

for CVID, they might ask about the increased risk to develop autoimmune diseases in adulthood, and for Bruton's , I think the tyrosin kinsae gene defect is the most tested point.

thank you all.
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