Nonlysozyme antibacterial factor in human tears. Fact or fiction?

The existence of nonlysozyme antibacterial activity in tear fluid was reinvestigated. Tear fluid was fractionated by ultrafiltration and affinity chromatography. The antibacterial activity, detected in native tear fluid, coincided with the presence of lysozyme in the fractions. No antibacterial activity could be detected by agar diffusion in the fractions that should contain the low molecular mass antibacterial factors of tear fluid, reported in the literature.