Competitive coexistence in antiviral immunity

Adaptive immunity to viruses in vertebrates is mediated by two distinct but complementary branches of the immune system: the cellular response, which eliminates infected cells, and the humoral response, which eliminates infec tious virus. This leads to an interesting contest, since the two responses compete, albeit indirectly, for proliferative stimuli. How can a host mount a coordinated antiviral campaign? Here we show that competition may lead t o a state of "competitive coexistence" in which, counterintuitively, each b ranch complements the other, with clinical benefit to the host. The princip le is similar to free-market economics, in which firms compete, but the con sumer benefits. Experimental evidence suggests this is a useful paradigm in antiviral immunity. (C) 2000 Academic Press.