Tuesday, 15 May 2012

Fighting blood cells with blood cells

by Jackie Woods

An article in the NY times outlines exciting recent research (abstract) that might eventually change the way we treat diseases of all types. The research discusses how one part of the human immune system can be altered genetically to heal itself of the disease that is leukaemia.

Leukaemia is a cancer of the blood and bone marrow. It starts in the bone marrow where developing white blood cells experience a cancerous change and start multiplying out of control. This eventually leads to the bone marrow being crowded, making it unable to continue producing normal blood cells. In Chronic Lymphocytic Leukaemia (C.L.L.), the cancerous change happens in the B-cells, one of 2 types of white blood cells.

Treatments have usually involved chemotherapy, which usually works by attacking fast-dividing cells. Beyond cancers, the chemotherapy also attacks hair follicles, bone marrow and digestive tract, so patients generally loose hair, feel tired (due to low blood cell numbers) and feel nauseous.

In this new treatment, an HIV-1 virus has its genes removed, making it unable to cause HIV but keeping its ability to transfer its contents to new cells. The virus is filled with genes from various animals that were chosen for a certain ability or skill useful in the fight against leukaemia. Then patients own T-cells (the other type of white blood cells) are exposed to the virus. The virus inserts the genes it is carrying, altering the genetic make up of the T-cells. These T-cells are then reintroduced to the body.

The changes made to the genes of the T-cell make it able to recognise B–cells (healthy or cancerous) and destroy them. This doesn’t happen easily – the cancer is effectively a larger infection in the body, and the T-cells must fight it, so the battle wages, with patients experiencing the usual symptoms of an infection - fevers, chills, fatigue, loss of appetite, nausea and diarrhoea. What makes this research special is that after these symptoms improved, two out of three patients had no signs of leukaemia in their bodies – they were in complete remission.

This kind of treatment had been trialled before, but researchers couldn’t find a way for the cells to multiply in the body (in vivo), and so the cells only lasted a short time in the body. This research has found a way to allow replication in vivo, an attribute I believe has made it possible for the treatment to truly be effective.

The down side to this treatment is that the patient is left without B-cells in the body, which are important for immune functioning. At this time, this can be managed with monthly injections, but I think the future of this research is in designing these disease-fighting viruses that can tell healthy from diseased, good from bad. I look forward to reading more about these fascinating developments as they occur.



Out of control… (XKCD 2012, sourced from http://www.xkcd.com/938/)


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