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1831849 tn?1383228392

New Tysabri/PML Screening Study

Food for thought for those on, or conteplating, Tysabri. Blood antibody testing for JCV may not be enough.

http://www.medpagetoday.com/Neurology/MultipleSclerosis/39649?xid=nl_mpt_DHE_2013-06-06&utm_content=&utm_medium=email&utm_campaign=DailyHeadlines&utm_source=WC&eun=g530414d0r&userid=530414&email=***@****&mu_id=5653774

Kyle
6 Responses
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572651 tn?1530999357
I'm glad you stuck that up for discussion - I glanced at it briefly yesterday and thought it was significant.  It made me think of you, Kyle, with the repeat LP to check for the virus.  I'm due for my next JC virus assay in July- I hope it continues to be negative, but I will definitely ask a few more questions than usual.
Helpful - 0
198419 tn?1360242356
Thank you Kyle!!!

Hope they expand that toolbox, and quick!
Helpful - 0
1831849 tn?1383228392
"So, is it that 4 of the 10 were JC antibody negative, BUT, had JC viral in their blood? I"

BINGO! :-)

It seems quite possible to have JCV DNA in your system but remain anti-body negative. In my last test, about 6 months ago, my blood antibody test came back positive, but my CSF remained negative. My Doc said it was OK to continue Tysabri for a wile. My inference was that JCV>PML does it's damage if it gets into your brain via CSF.

I think that the bottom line is that you really can't rely on the old blood antibody test alone. You need to look deeper. Thankfully they have the tools to do so!

Kyle
Helpful - 0
198419 tn?1360242356
Definitely a big chunk for me to have missed!

So, is it that 4 of the 10 were JC antibody negative, BUT, had JC viral in their blood? If so, wonder how the ab test doesn't catch this...

Guess this extra knowledge requires a degree in immunology, lol

I wonder further how frequent it is that people test positive for certain virus in blood but ab negative.

Again, I'm on a big learning curve here. So, if my thinking out loud if off because I'm misinterpreting the facts I apologize.
-Shell
Helpful - 0
1831849 tn?1383228392
My take away was that the standard JCV blood antibody test may give a false negative and thus a false sense of safety.

"Ten patients in the first group were found to have JC viral DNA in their blood, with four lacking a positive result in anti-JC virus antibody testing."

From this, 40% of the patients found to have JCV DNA in their blood but tested negative for the JCV antibodies. That's a pretty big chunk.

I do think it's important remember that being JCV+ is only one of the PML risk factors. There are three and you need at least two in order to be at risk. The other two factors are prior immunosuppressant therapy an more than 24 Tysabri infusions.

I read somewhere the other day that even if you have all three your risk is about 1 out of 100.

Kyle
Helpful - 0
198419 tn?1360242356
Just read it -
I had to look up viremia though, lol But, for those who read it, they speak about JC viremia positive ...viremia is is condition where virus enter the bloodstream.

Kyle - After reading this, I felt it doesn't seem it's anything new/different than what is practiced and recommended now...do you? Meaning they do repeat testing (but are they suggesting from below more broad viremia? Perhaps I'm not understanding the meaning of it)...Let me know if I missed something because I probably did :)
-Shell

All -
Here is an excerpt:
"To establish risk-stratification algorithms for PML in patients who receive potent immunomodulatory therapies, a single measurement of viral activity, such as a test for antibodies to JC virus, may be useful but not sufficient to assess risk," the researchers wrote. They recommended "a more comprehensive risk-mitigation strategy" that involves periodic testing during natalizumab treatment.

Natalizumab's label now calls for repeat serology testing every 6 months, citing the risk of new JC virus infections that may occur during treatment. Infections are relatively common in the general population. In the current study, 12 of the 18 healthy volunteers were seropositive
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