AT PRESENT, there is no simple and painless way to check whether a heart
transplant is in danger of rejection. But now British researchers are hoping
that a blood test which hunts for changes in the levels of many different
proteins could come to the rescue.
So far, the only reliable method is to take weekly samples from inside the
new heart and examine the cells for abnormalities. Because this is risky and
painful for the patient, as well as expensive, doctors have been looking for
non-invasive ways of spotting rejection that are just as sensitive.
To develop a better test, Jules Westbrook of Harefield Hospital in Middlesex
and his supervisor Michael Dunn are trying to identify changes in the levels of
heart proteins in the blood before rejection occurs. Westbrook incubated the
cell samples routinely taken from patients鈥� hearts in the weeks after a
transplant. Then he studied the proteins these cells produced using
electrophoresis鈥攁 technique that separates out proteins by dragging them
through a gel using electric fields. How far they travel along the gel indicates
their size and charge. At the same time, the samples were examined for signs of
rejection by the conventional method of looking for cell abnormalities.
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The researchers then compared the protein gels from patients rejecting their
hearts with gels from patients whose organs weren鈥檛 being rejected. This
revealed up to fivefold increases or decreases in the quantities of hundreds of
different proteins. 鈥淲hat we need to do now is identify these proteins,鈥�
Westbrook says. Then a simple test could monitor changes in the levels of these
proteins in patients鈥� blood. If signs of rejection were detected, doctors could
increase a patient鈥檚 dose of immunosuppressant drugs, saving their
heart鈥攁nd probably their lives.
Julio Celis of the University of Aarhus in Denmark uses exactly the same
approach to look for protein markers for diseases such as bladder cancer. Great
care must be taken to protect samples from contamination, he cautions, as
otherwise the data obtained will be less than useless.