The Concentration of Lysozyme in the Tears in Acute and Chronic Conjunctivitis

Immunoassay of tear lysozyme in conjunctival diseases

The tear lysozyme content in 111 normal subjects and in 159 patients with various conjunctival diseases was determined by a single radial immunodiffusion technique. Tear lysozyme level in normal people was 1.33/mg/ml. (SI conversion: mg/ml = g/l.) The mean tear lysozyme levels in patients with chronic irritative conjunctivitis (0.97 mg/ml) and nutritional deficiency with epithelial xerosis (0.76 mg/ml) were significantly lower than in the normal controls. The mean tear lysozyme levels in tears from patients with vernal conjuctivitis (1.20 mg/ml), phlyctenular conjunctivitis (1.10 mg/ml), and acute bacterial conjunctivitis (1.48 mg/ml) were not significantly different from those in the normal controls. Superimposition of acute bacterial conjunctivitis on trachoma did not alter the low tear lysozyme level that existed before in these patients.

Human tear lysozyme. A comparison of electro-immunodiffusion, radial immunodiffusion and a spectrophotometric assay

In 116 persons (67 men and 49 woman) the tear fluid of both eyes was collected using paper discs and once more after topical anaesthesia. After weighing the discs and eluting the tear fluid, the lysozyme content was measured using two immunological methods [radial immunodiffusion (RID) and rocket immuno-electrophoresis (RIE)] and a spectrophotometric assay. Standard curves were established with purified human lysozyme and egg-white lysozyme. In addition, albumin was determined in all the samples by rocket immuno-electrophoresis. All lysozyme assays showed a high degree of correlation, the spectrophotometric technique giving significantly lower values (compared with RID and RIE) when human lysozyme was used for standardization. The lysozyme content of the tears did not correlate with the fluid uptake in the discs, but showed a significant decrease with age, which was abolished by topical anaesthesia. In contrast, albumin levels were dependent upon the weight and independent of the age of the patient. It is suggested that the determination of albumin as a "reference protein' might help in comparing the results of different tear sampling techniques used by various groups, which induce variable amounts of reflex tearing.