Cell clue to Elephant Man trials

Scientists believe they may have discovered why six men were taken seriously ill following a disastrous drugs trial at a north London hospital.

At a conference in Paris, British experts revealed how cells in the body may have responded to the drug, TGN1412.

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Six men were taken ill in March at Northwick Park Hospital after being injected with the drug as part of a clinical trial.

The research shows how differences in the response of animals and humans to the drug may have led to the catastrophic effects.

Stimulating the molecule CD28 on T cells, which mediate the immune response, can have an adverse effect if the cells have in the past been activated and altered by infection or illness, the study shows.

When scientists artificially stimulated CD28 on previously activated T cells, it caused the cells to migrate from the blood stream into organs where there was no infection, causing significant tissue damage.

TGN1412 was known to activate CD28 strongly, the scientists said.

About 50 per cent of adult T cells are memory cells and have been activated by infections and illnesses in the past.

But animals, such as those used to test TGN1412 before the human trial, do not have many memory T cells because they are kept in a sterile environment and shielded from infections, the researchers said.

The study, funded by the British Heart Foundation (BHF), was led by scientists from Imperial College London, King's College London and the Babraham Institute.