13 July 1990
Vol 249, Issue 4965

About The Cover

A transmission electron micrograph (magnification ×16,000) of a human neutrophil that is degrading particles of antibody-coated, insoluble elastin in the presence of human plasma. Although endogenous plasma proteinase inhibitors cannot regulate neutrophil-mediated proteolysis at sites of tight cell-substrate contact, subjacent substrates can be protected from the attacking neutrophils by secretory leukoprotease inhibitor, a structurally unique proteinase inhibitor normally concentrated in human mucous secretions. See page 178. [Photograph by Andreas R. Huber, Sandra Regiani, Bruce Donohoe, and Stephen J. Weiss]