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Old 05-20-2010
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Immunology T cell defect

How come a normal WBC count rule out T cell defect?
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Old 05-20-2010
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I think that the answer lies to the pivotal role of T-helper cells in the function of the entire immune system. Th cells are necessary for the activation, maturation and proliferation of both cytotoxic T-cells (Th1 cell line) and B-cells (Th2 cell line). Consequently, a normal absolute lymphocytic count indicates not only that all lymph cell lines are working properly, but above all that the nodal Th-cell subtype is intact and co-ordinating the rest of the lymphocytic cell lines.
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Old 05-24-2010
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Quote:
Originally Posted by ath.pantelis View Post
I think that the answer lies to the pivotal role of T-helper cells in the function of the entire immune system. Th cells are necessary for the activation, maturation and proliferation of both cytotoxic T-cells (Th1 cell line) and B-cells (Th2 cell line). Consequently, a normal absolute lymphocytic count indicates not only that all lymph cell lines are working properly, but above all that the nodal Th-cell subtype is intact and co-ordinating the rest of the lymphocytic cell lines.

And it does not rule out B cell defect?
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Old 05-25-2010
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No, because defects of B-cells may well be qualitative (i.e. functional), apart from being quantitative. In other words, a pt may have a normal lymphocytic count and suffer from some kind of B-cell related immunodeficiency, nevertheless. This is the reason why B-cells defects are better evaluated by means of quantitative immunoglobulin measurements, which constitute an indication of the functional state of the B-cells.
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Old 05-25-2010
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Plz simplify?
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Old 05-25-2010
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I don't know how to make it simpler, because I don't know exactly what point you don't get. I'll give it a shot, however.

In the Complete Blood Count, the White Blood Cell Count indicates the percentages & the absolute number of each WBC category (i.e. PMNs, Lymphocytes, Eosinophils, Basophils & Monocytes). A normal lymphocytic count is a normal total of T-cells and B-cells added together.

T-cells participate in immunity by themselves (either cytotoxic immunity = CD8+, or assistance between antigen presentation & secretion of immunoglobulins = CD4+, or regulation of immune surveillance = Treg etc). This means that, for T-cells, it is true that a normal count signifies a normal function, in the context of immune deficiency screening).

On the contrary, a normal B-cell count does not necessarily indicate a normal B-cell function: the function of B-cells depends on their ability to secrete functional immunoglobulins (humoral immunity) and number of B-cells does not give any hint about their ability to secrete properly-functioning immunoglobulins. (P/S: antigen presentation is a secondary role of B-cells, of no major concern in the subject in question). For this reason, you need a method to evaluate the number of secreted immunoglobulins, in order to assess the integrity of B-cells.

Hope this clarifies things out. Otherwise, please be so kind as to explain further your area of uncertainty.
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Old 05-25-2010
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Quote:
Originally Posted by ath.pantelis View Post
I don't know how to make it simpler, because I don't know exactly what point you don't get. I'll give it a shot, however.

In the Complete Blood Count, the White Blood Cell Count indicates the percentages & the absolute number of each WBC category (i.e. PMNs, Lymphocytes, Eosinophils, Basophils & Monocytes). A normal lymphocytic count is a normal total of T-cells and B-cells added together.

T-cells participate in immunity by themselves (either cytotoxic immunity = CD8+, or assistance between antigen presentation & secretion of immunoglobulins = CD4+, or regulation of immune surveillance = Treg etc). This means that, for T-cells, it is true that a normal count signifies a normal function, in the context of immune deficiency screening).

On the contrary, a normal B-cell count does not necessarily indicate a normal B-cell function: the function of B-cells depends on their ability to secrete functional immunoglobulins (humoral immunity) and number of B-cells does not give any hint about their ability to secrete properly-functioning immunoglobulins. (P/S: antigen presentation is a secondary role of B-cells, of no major concern in the subject in question). For this reason, you need a method to evaluate the number of secreted immunoglobulins, in order to assess the integrity of B-cells.

Hope this clarifies things out. Otherwise, please be so kind as to explain further your area of uncertainty.
Ya man,that helps.Thanks a lot
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