Specific conversion of IL-8(1-77) to IL-8(7-77) by activated neutrophil gelatinase B.

Natural IL-8 occurs as 2 protein variants, IL-8(1-77) and IL-8(6-77), which are separable by SDS-PAGE. Activated gelatinase B processes natural (A) and recombinant (B) human IL-8(1-77) to a shorter form, identified as IL-8(7-77) (Table 1). To illustrate that this conversion was by activated gelatinase B, various inhibitors were tested for their ability to inhibit the chemokine conversion. The metalloproteinase inhibitors EDTA, o-phenantrolin (PHEN), and TIMP-1 and the gelatinase B–inhibiting monoclonal antibody REGA-3G12 inhibited this conversion completely, but no effect was visible with the serine protease inhibitors pefabloc and aprotinin or with the thiolprotease inhibitor E64. Progelatinase B or stromelysin-1 alone was unable to process IL-8. In B, the first 2 lanes (with the controls of the EDTA inhibition) contain twice the amount of IL-8 as the other lanes. S indicates relative molecular mass standard. The + and − symbols in the upper line indicate the presence or absence of the indicated inhibitors, whereas symbols 0, −, +, or P in the lower line indicate no incubation, incubation with stromelysin-1 alone, incubation with activated gelatinase B, or incubation with progelatinase B, respectively.