Adjuvants promote cell survival
The ability of individuals to respond to invading pathogens is dependent on immune cells called T lymphocytes. When T cells encounter pathogens they undergo rapid cell division followed by rapid cell death, leaving behind a small pool of "memory" T cells that protect animals from future attack by the same organism. Vaccination relies on developing a substantial pool of memory cells and that is why adjuvants, which can increase T cell survival, are so important. In the May issue of Nature Immunology (Vol. 2, No. 5, 01 May 01), Pippa Marrack and colleagues from the University of Colorado Health Sciences Center, Denver, CO report on how adjuvants promote T cell survival.
Marrack and colleagues used "gene chips", a new technology that facilitates the identification of many genes at once, to compare the genes expressed by T cells in the presence or absence of adjuvant. Of the many differences in gene expression by T cells that are under the influence of adjuvants and those that are not, one gene in particular, called Bcl3, caught the investigators' eyes. Bcl3, which belongs to a family of genes that promote T cell survival, was specifically "switched on" by adjuvants during an immune response.
The Denver group then tested this gene and found that it does, indeed, increase the life expectancy of T cells that had been exposed to antigen, perhaps by regulating a series of genes that together make for a "hardier" T cell. In a N&V, Andreas Strasser from Melbourne, Australia outlines how these authors show "that Bcl-3 is a critical regulator" of the cell death process in T cells. Thus, it is likely that one way in which adjuvants improve the efficacy of vaccines is by switching on Bcl-3, whose presence promotes T cell survival.
National Jewish Medical and Research Center
1400 Jackson Street, K 521
Denver, CO 80206-2761
U N I T E D S T A T E S
Tel: (+1) 303-398-1322
Fax: (+1) 303-398-1396
The University of Melbourne
Royal Melbourne Hospital
The Walter and Eliza Hall Institute of Medical Research
Royal Parade, Parkville, Gate 12
A U S T R A L I A
Tel: (+61) 3 9345 2555
Fax: (+61) 3 9347 0852
(C) Nature Immunology press release.
Message posted by: Trevor M. D'Souza