Stories [9]: A Healthy Volunteer

20 09 2010

The host of Next Grand Rounds (Pallimed) asked to submit a recent blog post from another blogger in addition to your own post.
I choose “Orthostatics – one more time” from DB Medical rants and a post commenting on that from Musings of a Dinosaur.

Bob Center’s (@medrants) posts was about the value of orthostatic vital sign measurements (I won’t go into any details here), and about who should be doing them, nurses or doctors. In his post, Bob Center also mentioned briefly that students were seeing this as scut work similar as drawing your own bloods and carrying them to the lab.

That reminded me of something that happened when I was working in the lab as a PhD, 20 years ago.

I was working on a chromosomal translocation between chromosome 14 and 18. (see Fig)

The t(14;18) is THE hallmark of follicular lymphoma (lymphoma is a B cell cancer of the lymph nodes).

This chromosomal translocation is caused by a faulty coupling of an immunoglobulin chain to the BCL-2 proto-oncogene during the normal rearrangement process of the immunoglobulins in the pre-B-cells.

This t(14;18) translocation can be detected by genetic techniques, such as PCR.

Using PCR, we found that the t(14:18) translocation was not only present in follicular lymphoma, but also in benign hyperplasia of tonsils and lymph nodes in otherwise healthy persons. Just one out of  1 : 100,000 cells were positive. When I finally succeeded in sequencing the PCR-amplified breakpoints, we could show that each breakpoint was unique and not due to contamination of our positive control (read my posts on XMRV to see why this is important).

So we had a paper. Together with experiments in transgenic mice, our results hinted that t(14;18) translocations is necessary but not sufficient for follicular lymphoma. Enhanced expression of BCL-2 might give make the cells with the translocation “immortal”.

All fine, but hyperplastic tonsils might still form an exception, since they are not completely normal. We reasoned that if the t(14;18) was an accidental mistake in pre B cells it might sometimes be found in normal B cells in the blood too.

But then we needed normal blood from healthy individuals.

At the blood bank we could only get pooled blood at that time. But that wasn’t suitable, because if a translocation was present in one individual it would be diluted with the blood of the others.

So, as was quite common then, we asked our colleagues to donate some blood.

The entire procedure was cumbersome: a technician first had to enrich for T and  B cells, we had to separate the cells by FACS and I would then PCR and sequence them.

The PCR and sequencing techniques had to be adopted, because the frequency of positive cells was lower than in the tonsils and approached the detection limit. ….. That is in most people. But not in all. One of our colleagues had relatively prominent bands, and several breakpoints.

It was explained to him that this meant nothing really. Because we did find similar translocations in every healthy person.

But still, I wouldn’t feel 100% sure, if so many of my blood cells (one out of 1000 or 10.000) contained t(14:18) translocations.

He was one of the first volunteers we tested, but from then on it was decided to test only anonymous persons.

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7 11 2010
Un equipo de la Clínica Universidad de Navarra y el CIMA lidera un ensayo clínico internacional para producir, con plantas de tabaco, nuevas vacunas personalizadas contra el linfoma folicular. « RDi Press

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