Granule matrix proteins secreted from human neutrophils after ionomycin stimulation were separated by SDS-PAGE, blotted onto a polyvinylidene diflouride (PVDF) membrane and overlaid with the mannose-binding lectin concanavalin A (Con A) or Escherichia coli bacteria exposing type-I-fimbriae. Four proteins of approximately 30, 40, 70 and 80 kD, respectively, derived from both the azurophil and the specific granules were shown to expose mannose-containing structures by binding of Con A. Such reactivity was also shown for a 90-kD protein from the light membrane fraction enriched in plasma membrane and secretory vesicles. When blots of granule matrix proteins were exposed to type-I-fimbriated bacteria, a total of seven proteins was recognized; four of the five Con A-binding proteins (40, 70, 80 and 90 kD) was detected also by the bacteria in addition to three proteins not detected by Con A (50, 60 and 100 kD). The role of the secreted type-1-fimbriae binding proteins as anti-adhesin candidates is discussed.