HOW LEISHMANIAS FOOL THE IMMUNE SYSTEM (01/11/96)

Viruses, bacteria and parasites must find a way to get around the immune system in order to reproduce inside the body. Some change constantly to avoid being recognized, while others remain "visible" but entice the body to opt for an ineffective immune response. Researchers at the Molecular and Cellular Pharmacology Institute in Valbonne (CNRS) and the Center for Biochemistry in Nice (INSERM) recently showed that the latter mechanism is used by leishmanias. These small protozoans are transmitted by insect bites and cause leishmaniasis; they are parasites that express a specific protein called LACK. This protein forces the organism to produce antibodies, which are ineffective against protozoans. It also blocks the activation of macrophages, the only cells capable of eliminating the parasite. What are the potential applications of this discovery? One possibility lies in preventing the immune system from reacting in the presence of the LACK protein. This would be comparable to "desensitization," a technique currently used to treat allergies. It may prove more effective than classic vaccination methods which, for the time being, are rarely able to defeat organisms as complex as parasites.

Partial support for this program was provided by the Conseil Régional of the Provence-Alpes-C^te-d'Azur Region and the World Health Organization.

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