Doctors caring for the six human guinea pig victims of the disastrous TeGenero drug trial have discharged two of the men. Three others remain as in-patients at Northwick Park Hospital, London, while one man is still in a critical condition after being administered an experimental immune treatment more than two weeks ago.

The hospital is staying tight-lipped on the prognosis for the critical patient, but says he has shown some signs of improvement. The released volunteers will continue to receive treatment and be monitored as out-patients.

The men were given TGN1412, an antibody designed to suppress the destructive power of immune cells in diseases like rheumatoid arthritis and leukaemia. The problems didn't show up in animal trials.

Speculations about what caused the reaction have centred on contamination of the doses by bacterial toxins, and a paradoxical super-activation of the volunteer's immune system.®

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