HOPES of protecting people against some of the most dangerous sexually transmitted diseases have been boosted by the first test of a new method of immunisation. A team in Montana has immunised mice against Chlamydia, a bacterium that can cause infertility in women. The same approach might even work against HIV.
Until now, vaccines have been notoriously unsuccessful at stimulating immune responses in the mucous membranes ofthe body, the route through which HIV, Chlamydia and other sexually transmitted pathogens enter the body. And though vaccines are good at stimulating antibody-producing B cells, they are poor at triggering T cells to destroy infected cells. T cells are vital in the fight against Chlamydia and HIV.
So Harlan Caldwell and his colleagues at the Rocky Mountain Laboratory of the National Institute of Allergy and Infectious Diseases (NIAID) in Montana tried a different approach. They took bone marrow from female mice and cultured dendritic cells by adding interleukin-4. Dendritic cells recognise foreign molecules and recruit other cells of the immune system to attack invaders. The team added heat-killed Chlamydia to the culture to sensitise the dendritic cells to the bacterium and then put the cells back into mice.
This technique is already used against some cancers, where dendritic cells are sensitised to cells taken from the patients' own tumour. But this is the first time it has been used to immunise against infectious disease, says Caldwell.
When the immunised mice were later exposed to live Chlamydia, their
response was as vigorous as that of mice immune to the disease because of a
prior infection, and none developed signs of disease (The Journal of
Experimental Medicine, vol 188, p 809). The dendritic cells triggered the
appropriate immune response in the mucous membrane of the vagina, says Caldwell.
Caldwell is optimistic that the technique will work in people. Some form of
vaccination is badly neede
Contact: Claire Bowles
44 171 331 2751