Transplantation: Timing critical in blocking inducible costimulator

drj writes "Harada et al. report the survival of mouse heart transplants differing at major (MHC) histocompatibility antigens was prolonged by early or late costimulation blockade. ICOS-B7h costimulation was blocked with rat monoclonal antibodies on days 0-6 (early) or days 4-10 (late). For grafts differing at minor histocompatibility antigens, however, early blockade accelerated rejection while late blockade prolonged graft survival. The authors attribute the difference to the frequency of responding T cells (more against MHC, fewer against minor antigens) and also suggest implications for autoimmune disease therapy. These findings raise important considerations for applying immunomodulating therapies. (originally posted on MedDot.org Aug 11, 2003)
PubMed Abstract, Full Text JCI