Characterization of ocular mucus extracts by crossed immunoelectrophoretic techniques

Crossed immunoelectrophoresis (CIE) and crossed immunoelectrofocusing (CIEF) were used to characterize proteins and mucosubstance in the saline extract of human ocular mucus pooled from the normal eyes of donors. CIE resolved more components with greater specificity than previous techniques. Up to 25 components were identified. Lactoferrin, protein G, tear prealbumin, and ocular mucosubstance were found to be ocular-specific. CIE also allowed for the study of protein associations of: 1) albumin-alpha 1-antitrypsin; 2) albumin-tear prealbumin; and 3) IgA-secretory component and lactoferrin-mucosubstance. CIEF revealed that most of the proteins were in the pI range of 4.6-7.4. Up to 19 components were identified. Protein associations revealed by CIE were not evident by CIEF. These results provide a basis for future comparative analyses of tear and mucus from normal and diseased eyes, essential for a better understanding of tear and mucus function.