Hemolytic complement in tears

We performed hemolytic assays for C1, C4, C3 and C5 on tear samples from 7 normal subjects and 10 patients with corneal ulcers. Hemolytic activities in tears were determined by 50% hemolysis of sensitized sheep red blood cells. Absent or low hemolytic activities of C1, C4 and C3 were found in normal tears. C5 was detected in tear samples from 4 of 7 normal subjects. Tear samples from patients with corneal ulcers showed elevated levels of C1, C4, C3 and C5, but wide ranges in values were found. C5 had the highest hemolytic activities in both normal tears and tears from eyes with corneal ulcers. Complement in tears may contribute to host defense in microbial corneal ulcers.