Friday, July 2, 2010

Week 3 - Julian Palacios

This week I spent mostly in the lab where I learnt all the intricacies of real-time PCR and the theory about organ rejection and kidney rejection in particular. Dr. Suthanthiran´s lab has discovered several markers that inform about the state of rejection. Today the only reliable method that exists to determine if the patient is suffering from an episode of acute rejection of the transplanted kidney is to perform a biopsy and take samples of the kidney to the lab. What we are doing in the lab is to perform these diagnostics by only looking at the urine of the patient, or alternatively the blood. The urine has cellular material, more specifically rna, that can be traced back to the immune cells that have attacked the foreign kidney. For example, we can look at the levels of expression of certain proteins like perforin which are expressed by the immune cells, T-cells, when they attack a foreign body. If the levels of rna for perforin are high, this means that the cells are producing large amounts of perforin and there is thus a period of acute rejection. Interestingly, I found that there is a certain type of immune cell whose job it is to halt the attack. These are called regulatory T-cells, and there is less rejection of the kidney when these cells are more active. It is thus also possible to predict what will happen after an episode of acute rejection by looking at the activity of these cells. If these cells are active then the episode of acute rejection will not be very intense. Genes like FOXP3 can be used to detect the presence of these regulatory T-cells and more are being discovered in our lab. I learnt that there are several types of immune rejection. One is cell mediated via T-cells, another is mediated by antibodies produced against the foreign body, and a third is called vascular rejection. There are different kinds of treatment for each type of rejection. For example, steroids are used for T-cell mediated rejection, and part of the job in our lab is aimed at reducing the amount of steroids that patients have to take after a transplantation. A type of treatment is immunosupressants. I found interesting that doctors know if they are giving the patient too many immunosupressants when they take a biopsy of the kidney and look for the presence of viruses. Viruses thus emerge spontaneously in the kidney only if the immune system is low.  When they reduce the daily dose of immunosupressants, the immune system will be slightly better off, and the viruses will disappear. In the near future I plan to learn about the work on our lab related to micro rna and I plan to see the first liver transplants performed at the presbyterian hospital after several years where none has been performed.

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