Polycythemia vera and LAP

[Dark tar]

Is there a logical reason why LAP is elevated in Polycythemia vera?? I know it's low in CML and high in leukomoid reaction (malignant leukocytes lack the enzyme) however I can't link this to the polycythemia vera. Please help.

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[Transposony]

Is there a logical reason why LAP is elevated in Polycythemia vera?? I know it's low in CML and high in leukomoid reaction (malignant leukocytes lack the enzyme) however I can't link this to the polycythemia vera. Please help.

Polycythemia vera has increased number of normal leukocytes. More leukocytes, more Alk Phos.

 

[Dark tar]

Polycythemia vera has increased number of normal leukocytes. More leukocytes, more Alk Phos.

Thanks for replying Transposony. Forgive my ignorance but how is a cancer associated with normal cells? If you could explain more I'd be very grateful.
Thanks

 

[seminoma]

Thanks for replying Transposony. Forgive my ignorance but how is a cancer associated with normal cells? If you could explain more I'd be very grateful.
Thanks

Lots of cancers make functional cells.

 

[Transposony]

Thanks for replying Transposony. Forgive my ignorance but how is a cancer associated with normal cells? If you could explain more I'd be very grateful.
Thanks

Polycythemia vera is a myeloproliferative (stem cell) disorder. So there is a neoplastic proliferation and maturation of erythroid, megakaryocytic and granulocytic progenitors.
There is an up-regulation of the EPO receptors due to mutation in the tyrosine kinase (JAK2) leading to increased production due to clonal hyperplasia of these cells lines in the marrow.

 

[Transposony]

It might also help to know that ruxolitinib, an inhibitor of Janus-associated kinase enzymes is used for the treatment of polycythemia vera in patients who have an inadequate response/cannot tolerate hydroxyurea.

 

[Transposony]

Also, there are increased B12 levels in Polycythemia vera as well as CML due to increased synthesis of B12 binding protein (haptocorrin) by both normal and malignant cells respectively.

 

[deleted564496]

Also, there are increased B12 levels in Polycythemia vera as well as CML due to increased synthesis of B12 binding protein (haptocorrin) by both normal and malignant cells respectively.

When do you sit for the exam? You're gonna kill it.

 

[Dark tar]

Polycythemia vera is a myeloproliferative (stem cell) disorder. So there is a neoplastic proliferation and maturation of erythroid, megakaryocytic and granulocytic progenitors.
There is an up-regulation of the EPO receptors due to mutation in the tyrosine kinase (JAK2) leading to increased production due to clonal hyperplasia of these cells lines in the marrow.

Ah-haaa thanks for clarifying dear Transposony !!! So does ESSENTIAL THROMBOCYTHEMIA have increased LAP as well as it has the same JAK2 gene involved?

Also isn't haptocorin produced by the salivary glands to bind B12 and protect it from stomach acidity?

Thanks a lot

 

[aspiringmd1015]

does it increase the EPO receptor? i thought the jak/stat was downstream of the receptor

 

[seminoma]

does it increase the EPO receptor? i thought the jak/stat was downstream of the receptor

Jak2 is the tyrosine kinase that the EPO receptor signals through. You can stimulate the receptor all you want but if the kinase is blocked nothing will happen.

Like pouring water into a cup. If I cut out the bottom of your cup you'll never be able to drink from it.

 

[aspiringmd1015]

right, but Transposony had said that there is an upregulation(ie increased amount of EPO receptors) but i thought the pathogenesis behind PV was a jakstat mutation that made it constitutevely acitve, which would work downstream of the receptor, so the actual # of receptors arent increased, and the jakstat is sending growth signals to the nucleus.

 

[Transposony]

right, but Transposony had said that there is an upregulation(ie increased amount of EPO receptors) but i thought the pathogenesis behind PV was a jakstat mutation that made it constitutevely acitve, which would work downstream of the receptor, so the actual # of receptors arent increased, and the jakstat is sending growth signals to the nucleus.

That's because it also functions as an obligate chaperone for these receptors in the Golgi apparatus and is responsible for their cell-surface expression.

 

[aspiringmd1015]

oh wow, nice. so the increased jakstat sends prolif signals and increases expession of epo receptors, cool.

 

[Dark tar]

I don't think it increases the receptor expression per se. Rather the mutant JAK-2 kinase is working now without much stimulus from epo (so it is now independant of its ligand). JAK2 is a tyrosine kinase and therefore its effects lead to survival ،maturation and differentiation of the effected stem cell.