ABSTRACTDermatophytes are the most common cause of superficial mycoses in humans and animals. They can coexist with their hosts for many years without causing significant symptoms but also cause highly inflammatory diseases. To identify mechanisms involved in the modulation of the host response during infection caused by the zoophilic dermatophyteArthroderma benhamiae, cell wall-associated surface proteins were studied. By two-dimensional gel electrophoresis, we found that a hydrophobin protein designated HypA was the dominant cell surface protein. HypA was also detected in the supernatant during the growth and conidiation of the fungus. TheA. benhamiaegenome harbors only a single hydrophobin gene, designatedhypA. AhypAdeletion mutant was generated, as was a complementedhypAmutant strain (hypAC). In contrast to the wild type and the complemented strain, thehypAdeletion mutant exhibited “easily wettable” mycelia and conidia, indicating the loss of surface hydrophobicity of both morphotypes. Compared with the wild type, thehypAdeletion mutant triggered an increased activation of human neutrophil granulocytes and dendritic cells, characterized by an increased release of the immune mediators interleukin-6 (IL-6), IL-8, IL-10, and tumor necrosis factor alpha (TNF-α). For the first time, we observed the formation of neutrophil extracellular traps against dermatophytes, whose level of formation was increased by the ΔhypAmutant compared with the wild type. Furthermore, conidia of the ΔhypAstrain were killed more effectively by neutrophils. Our data suggest that the recognition ofA. benhamiaeby the cellular immune defense system is notably influenced by the presence of the surface rodlet layer formed by the hydrophobin HypA.