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Wednesday, 31 December 2014

What is plasma treatment?

It’s reported in the press that a health care worker, recently diagnosed with Ebola, is being offered plasma treatment in a London hospital. This involves a transfusion of plasma from patients who have recovered from Ebola.
Plasma (blood with the cells removed) is a rich broth, full of antibodies and other immune proteins. The treatment should perhaps be re-named “antibody transfusion”.
When there's a new, unfamiliar infection the adaptive division of the immune system takes a while to set up a production line for the appropriate antibodies. First, a wandering immune cell detects the presence of a virus or bacterium and carries it to a lymph node where it's examined by passing lymphocytes. If a lymphocyte identifies it as a new threat it settles down in the lymph node, cloning a huge number of identical self-copies. These are then released (into the plasma) with the capacity to flood the body with millions of copies of the newly minted antibody. It is this lymphocyte-cloning process that takes several days.
The danger is, that in a disease like Ebola, a patient could die before their own antibodies can be produced in sufficient quantities to eliminate the virus. An infusion of antibodies from a recovered patient has the potential to keep them alive until their own production gets up to speed.
From the late 1890s plasma has been used to treat infections. Often the donor was a horse, which had been inoculated with a virus or bacterium causing it to form ample quantities of the antibody. The technique saved many lives but had its disadvantages – the need to keep large stables of horses and the risk of developing immune reactions to equine plasma proteins to name but two. The practice declined rapidly with the discovery of antibiotics and other modern drugs.
Plasma donated by human Ebola survivors has proved useful in previous outbreaks and is probably the best treatment currently available. As with any type of blood transfusion donors should be screened for viruses such as HIV. WHO has recently issued guidelines.
I’m sure we all hope that in this current UK case it will prove successful.

Saturday, 20 December 2014

Scientists synthesise antibodies

This week scientists at Yale University have announced one of those game-changing achievements that could change the future of medicine. And, probably, win a Nobel prize. They have synthesized mini-antibodies that can function within the body and attack both cancer cells and disease-causing agents.
An antibody is a highly complex macro-molecule, produced by the adaptive division of the immune system. It’s a powerful bespoke weapon that will only attack a single type of bacterium, a particular strain of virus or a cancer cell with a particular genetic signature. They lock on to receptors on the surface of the pathogens and disable them. Imagine them as tiny wheel clamps that are individually designed for each new make of car that comes on the market. One of the problems with antibody production is that it is not instant. It takes the immune system several days or weeks to get its production line up to speed and in a serious disease like Ebola, the patient can die before enough antibodies are produced. Once the antibody template has been produced, it can be used more swiftly whenever the particular threat re-appears.To work on cancer cells the immune system first has to identify them as alien.
Antibodies are tiny and these new synthetic antibodies even smaller. Picture a bespoke wheel clamp on a jumbo jet. But that might make them easier to produce.
Currently there are just a few ways in which medicine can use antibodies:
Vaccines – in which the body is induced to create a new type of antibody without becoming ill. New vaccines are hard to develop.
Extracting antibodies from blood of those previously infected. This is being tried currently to treat Ebola.
Snake bite serum – produced by injecting animals with small amount of venom and then extracting antibodies from blood serum.
Monoclonal antibodies – producing an individual antibody type in the lab, using a complex biological system.
If simpler synthetic antibodies could be produced by a less laborious process than monoclonal antibodies it would open the door to a wide range of options in treating infectious diseases and cancers.
A ground breaking moment in immunology without a doubt.

Wednesday, 10 December 2014

The immune system cleans up

The immune system is a teeming mass of interacting cells and complex organic chemicals that enable our bodies to deal with microbes. Immunologists have been toiling away for decades now and their research is, these days, at the level of individual molecular pathways. There are millions of these pathways – the circuit diagrams in an unimaginably complex computer.
One of the less well-known roles of the immune system is to identify and remove faulty, worn out or cancerous body cells. In other words it doesn't just fight off intruders, it declutters the house as well. It is fundamental to the immune system that it must, every day, make millions of judgements about what is ‘self’ and ‘not self’ so that it knows whether or not action is needed. It seems that cells that don’t pass its quality control process become re-classified as no-longer-self and dispatched for recycling.
Research into the molecular mechanisms of this decluttering process is beginning to lead to new medical treatments. 
In one recent report, a drug has been used (on a small group of patients) to block a molecule that enables bladder cancer cells to prevent an immune attack. The results are looking promising. The cancer cells disguise themselves as ‘self’ and the immune system ignores them. But the compound whips away the disguise and enables the malignant cells to be identified and destroyed. Treatments based on discoveries like this could eventually replace chemotherapy, which uses cytotoxic chemicals that inevitably damage healthy tissues.
In another study, a potential new treatment for malaria has been discovered and is ready to progress to safety trials in humans.
The malaria parasite makes its home inside healthy red blood cells. A couple of million red blood cells are produced every second by the bone marrow, so an equivalent number of worn out cells must be efficiently destroyed and removed from circulation. After detailed research into the genetics and cellular mechanisms of the parasite and into the way the immune system disposes of blood cells, a compound has been discovered that seems to hasten the disposal of malaria-infected cells and clear the parasite from the blood of mice. This is hopeful news when you consider the toll that malaria takes, particularly on young children.

There is an enormous amount of fundamental research that has brought immunology to this point - mountains of Ph D theses and thousands of careers bent over the laboratory bench. This kind of research is not funded by drug companies and the fact that it is now, finally, beginning to produce treatments highlights the need to maintain public funding for pure science.