An antibody that blows up platelets

Immunologic thrombocytopenia, a frequent complication of HIV-1 infection, is associated with circulating immune complexes that contain platelet membrane components and anti-platelet membrane GPIIIa49-66 IgG antibodies. In September 7 Cell, Michael Nardi and colleagues from New York University School of Medicine show that anti-platelet GPIIIa49-66 IgG alone can causes platelet fragmentation independent of complement, via the induction of reactive oxygen species.

Nardi et al. found that purified anti-GPIIIa49-66 causes in vivo platelet fragmentation in wild-type and complement-deficient mice. In addition, in vitro experiments with inhibitors of reactive oxygen species, and in vivo studies carried out with p47phox-deficient mice showed that the complement-independent platelet lysis is caused by the antibody-induced generation of H₂0₂ (Cell 2001, 106:551-561).

"This was an unexpected finding because antibodies had never been shown to act in this fashion," said Simon Karpatkin the senior author of the paper. "We believe that this discovery could be of use in the ...