MOUSE HELPS ID CANCER-CAUSING GENEResearchers at Washington University in St. Louis reportdeveloping a transgenic mouse model for human follicularlymphoma that has led to the identification of a new type ofcancer-causing gene.

Writing in today's issue of Nature, Timothy J. McDonnell andStanley J. Korsmeyer suggest that a protein called Bcl-2 maycause follicular lymphoma by extending the life span of B cells,the white blood cell class that makes and secretes antibodies.

The mouse model allows scientists to follow tumor progressionfrom a resting state to a malignant lymphoma. Anunderstanding of the genetic and biochemical bases oflymphomas could lead to drugs for preventing and treatingsuch tumors.

Companies such as Xoma Corp. and ImmunoGen Inc. aredeveloping immunotoxins to treat lymphomas. (For furtherinformation, keyword search Industry Library for032290MABS.)

Humans with follicular lymphoma, the most common humanlymphoma, have hybrid chromosomes in which a deregulatedBcl-2 gene is joined to a human antibody gene. Introducing thehuman Bcl-2-antibody hybrid into mice led to transgenicanimals that had three to four times the normal number of Bcells. In two years, 11 percent of the mice had lymphomas.

The authors propose that the rise in B cell numbers was due toincreased B cell survival rather than increased B cell growth.They contend that Bcl-2 could be the first of a new class ofcancer-causing genes that are "antidotes against death."

PROTECTIVE ROLE FOR IGE ANTIBODIES

Besides causing allergic reactions, immunoglobulin E (IgE)antibodies appear to protect humans from reinfection byparasitic flatworms, researchers report in another Naturearticle.

Researchers, led by Paul Hagan of the National Institute forMedical Research in London, show that children in a smallcommunity in the West African nation of Gambia frequentlysuffer from infection by the flatworm Schistosomahaematobium, but are rarely reinfected by the flatworm afterage 15. These individuals are by then producing high levels ofIgE antibodies that appear to neutralize the parasite.

The slow development of IgE immunity seems to be influencedby IgG4 antibodies, which appear to block IgE's protectivefunction.

Companies developing allergy diagnostics and therapeuticstargeted at blocking IgE include Tanox Biosystems, Ciba-Geigy,Schering AG's Codon Corp., Immunotech, Mast Immunosystems,Quidel and Schering-Plough's DNAX Research Institute.

(c) 1997 American Health Consultants. All rights reserved.

No Comments