A CONTROVERSIAL treatment for AIDS, in which patients are given blood plasma
from people with HIV who are still healthy, benefits the donors as well as the
recipients, according to the team that pioneered the technique.
The scientists, led by haematologist Abraham Karpas of the University of
Cambridge, believe their discovery could provide doctors with a cheap way of
delaying AIDS in people with HIV. Other researchers say the results are
intriguing, but want to see more evidence.
For the past 10 years, Karpas has promoted the idea that donations of plasma
from relatively healthy HIV-positive patients can boost the immune systems of
people with AIDS. He suggests that the plasma provides a pool of fresh
antibodies to mop up the virus, and points to encouraging results from a French
clinical trial, reported in 1995 in Proceedings of the National Academy of
Sciences (vol 92, p 1195). Other scientists are sceptical, however. 鈥淭here
is certainly no consensus that passive immunotherapy offers any benefit to
people with AIDS,鈥� says Edward King, editor of Britain鈥檚 National AIDS
Manual.
Advertisement
The new results, suggesting an advantage to the donors, come from safety
tests to check that they were not harmed. In the latest Philosophical
Transactions of the Royal Society B (vol 352, p 764), Karpas鈥檚
team reports that over three years, the numbers of CD4 cells鈥攌ey immune
cells killed by HIV鈥攔ose in a sample of 26 donors. By contrast, there was
a steady decline in CD4 cells in a control group who were not donors. None of
the patients was on anti-HIV drugs. 鈥淭his technique may delay the progression to
AIDS by several years,鈥� claims Karpas. 鈥淎nd it鈥檚 cheaper than giving them
combination drug therapy.鈥�
Karpas has also collaborated with a team at the Southern New England
Community Consortium in Greenwich, Connecticut, to monitor 51 American plasma
donors. This study, due to be published in the journal Biotherapy,
produced similar results.
鈥淭hese are intriguing, preliminary data,鈥� says Frances Gotch of the Chelsea
and Westminster Hospital in London, an expert on HIV immunology. But she says
that the researchers need to provide more data on the fate of other types of
immune cell, and on the amount of virus circulating in the patients鈥� bodies. 鈥淚
feel the results have been overinterpreted,鈥� she says.
Karpas speculates that the beneficial effect he has recorded works through
some form of feedback effect, boosting antibody production.
鈥淭here is a precedent for this,鈥� notes Douglas Fearon, an immunologist at the
University of Cambridge. Patients with the autoimmune disease myasthenia gravis
sometimes have plasma removed to reduce levels of antibodies. 鈥淏ut it鈥檚 usually
short-lived,鈥� says Fearon. 鈥淭here鈥檚 a rebound phenomenon and levels start
rising鈥攕ometimes even higher than they were originally.鈥�