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ICI
2001: Vaccination, vaccination, vaccination
July
27th, 2001
by Bea Perks
Five thousand immunologists from around the world met in Stockholm for this
year's International Congress of Immunology (ICI). "We speak for one
of the most important biosciences in the world," said Gustav Nossal,
chair of the committee overseeing the World Health Organization (WHO)'s
Global Programme for Vaccines and Immunization. Vaccination was high on the
agenda, from serious talk about therapeutic vaccines to hearing one of
several Nobel laureates present argue that an HIV vaccine is "an
impossible dream". Debates such as this, on "current controversies",
were a highlight.
The conference, organized every three years by the International Union
of Immunological Societies (IUIS), was run this year jointly with IUIS
member, the Scandinavian Society for Immunology. "This is the most
important conference in the world in this field," said IUIS President
Fritz Melchers. It's so all encompassing, he said, that "these 5000
people are actually attending 20 conferences."
In the year of the 100th anniversary of the Nobel Prize - one in 10 of
which have gone to immunologists, notes Nossal - presentations came from
Nobel laureates Peter
Doherty, Rolf
Zinkernagel, and David
Baltimore.
In one of a series of debates on "current controversies", a
conference feature that delegates applauded, Baltimore was persuaded to
argue that an HIV vaccine is an
impossible dream. In this case, delegates quickly reached a consensus,
agreeing that the goal of developing an HIV
vaccine is much more than a dream.
Vaccination was high on this week's agenda, and well illustrates the
interface between clinical and basic research - a main focus of the
congress.
It is clear that the traditional view of immunization as a prophylactic
agent is fast making way for the arrival of therapeutic vaccines.
Cancer vaccine development was much in evidence. "Five years ago
people were laughing at us, but now [cancer vaccines] are becoming a
reality," Kees Melief, from the University of Leiden, told BioMedNet
News.
Melief alerted delegates to a potential drawback of current cancer
vaccine strategies, and a possible solution to the problem, at least in
mice. The remedy may involve the removal
of regulatory T cells.
And while Melief removes one set of T cells, a French team is busy
activating another group.
Claude Leclerc at the Pasteur Institute unveiled tentative plans for
early clinical trials of a vaccine that triggers
cytotoxic T lymphocytes to destroy cancer cells. A CTL response is
normally achieved only with more risky live attenuated vaccines. Leclerc
hopes that her method, which uses non-infectious viral particles, will be
both effective and safe.
Marie-Christine Béné from Laboratoire d'Immunologie Faculté de Médecine
de Nancy, in France, touched on the failure of early attempts to design a
contraceptive vaccine.
Plans to administer antibodies against ovarian antigens some years ago
had faltered when it became clear that the process was irreversible. Now
such vaccines are restricted to attempts at keeping down the fox
population, she added. But new studies of antibodies against ovarian
antigens might be leading Béné towards the opposite goal - towards
improving fertility.
Béné revealed an immunological complication of in vitro
fertilization (IVF). Ovaries are hyperstimulated to release large numbers
of eggs for IVF treatment, but this process also stimulates the immune
system.
The ovary's contents, which normally enjoy "immune exclusion"
(because they are not in contact with the circulation), then become exposed
when the ovary is punctured to release eggs. This releases a large amount
of antigenic material into the circulation, which can sometimes lead to the
development of auto-antibodies against ovarian antigens.
Those auto-antibodies can then trigger rejection of the fertilized egg
implant, a factor that could help to explain the high failure rate of IVF
treatment, says Béné. She is currently trying to characterize the
auto-antibodies responsible, with a view to designing future therapies to
improve the IVF success rate.
But while vaccination, in all its forms, was perhaps a central theme of
the meeting, there were numerous recurring themes throughout this
twenty-for-the-price-of-one meeting.
The latest work on stem cells attracted much attention.
Irving
Weissman, a pioneer of stem-cell research, revealed the discovery of a
protein that encourages hematopoietic stem cells to self-renew. These stem
cells have always differentiated into mature blood cells under experimental
conditions, but Weissman's team can now expand the number of stem cells in
vitro.
Nossal called for a shift in the debate over the use of embryonic stem
cells.
"I would like to see this progress as a basic science debate rather
than a human therapy debate," he said. The ethical debate is clouding
the more basic and immediate issues, he says.
Nossal balks at the hurdles facing neurologists contemplating stem cell
transplants from embryos into ageing adult tissue. Embryonic development is
very precisely regulated in terms of timing and location, he says. Consider
a brain lesion in a 65-year old stroke patient: "It really beggars the
imagination that you could just pop in some embryonic cells."
The meeting began with a presentation made by Fritz Melchers to the Bill
and Melinda Gates Foundation, in gratitude for their financial contribution
towards combating the three diseases, malaria, TB and HIV, which have been
singled out by international organizations, including the WHO and the
European Union, for a concerted research effort. The award was collected by
Margaret
Liu, the foundation's vaccine adviser.
The foundation has so far earmarked $1.3 billion over five years to
fight the three diseases, the same figure that leaders of the G8 countries
last week agreed to contribute annually, remarks Nossal."It's not a
criticism [of the G8 countries]," he told BioMedNet News,
"but it's rather piquant."
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