The excretory duct of the lacrimal gland of rabbits and guinea pigs was cannulated in situ for collection of pure lacrimal gland fluid, not contaminated by secretions from the Harderian gland or contributions of desquamating cells of the conjunctival and corneal epithelium. Tears as well as lacrimal gland fluid of both species showed a species-specific and molecular weight-dependent pattern after sodium dodecylsulphate-polyacrylamide (SDS-PAA) gradient slab gel electrophoresis. The most striking difference in both species was a protein corresponding to serum albumin present in tears and almost lacking in lacrimal gland fluid. Likewise, a variety of enzymes, total protein and PGE2 were measured in tears and lacrimal gland fluid. For rabbit tears the lacrimal gland is the primary tissue source of lysozyme (LZM), beta-hexosaminidase (beta-hex), angiotensin-converting enzyme (ACE), plasminogen activator (PA) and total protein, while lactate dehydrogenase (LDH) and the greater part of prostaglandin E2 (PGE2) are present in rabbit tears mainly as products from other ocular tissue sources. In guinea pig tears peroxidase (POD), ACE, PA and less PGE2 are exceted by the lacrimal gland, amylase (AMY), LDH and a substantial amount of PGE2 are added to the guinea pig tears by other ocular tissue sources. Beta-hex and total protein are released from the lacrimal gland and from other ocular tissue sources as well.

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The deposition of fibrin on infected vegetations and the presence of mononuclear phagocytes that have phagocytized bacteria are remarkabe features in experimental bacterial endocarditis. In a study in vitro, we show that phagocytosis of bacteria by human monocytes enhances thromboplastin generation by these cells. Maximal enhancement of the generation of thromboplastin by monocytes was about six times compared with that in the control experiment without bacteria, and it was obtained by preincubation of the monocytes with 5 to 10 bacteria per monocyte. No quantitative difference was observed between Staphylococcus epidermidis and Streptococcus sanguis as to the enhancement of the monocyte thromboplastin generation. An enhancement of the procoagulant activity generation was also observed after addition of bacteria to human or rabbit whole blood. Probably, this generation was also due to synthesis of thromboplastin by monocytes. It is conceivable that fibrin deposition on infected vegetations during bacterial endocarditis is mediated by thromboplastin synthesis by monocytes.

Human tear fluid has plasminogen activator activity. The type of plasminogen activator activity in unstimulated and stimulated tears was determined, using antibodies that specifically neutralize tissue plasminogen activator or urokinase. All plasminogen activator activity was tissue plasminogen activator-related in both types of tears. Correlations between activities of β-hexosaminidase, lysozyme and lactate dehydrogenase with tissue plasminogen activator acitvity indicate that the contribution to plasminogen activator activity of conjunctival and corneal epithelium is more important in unstimulated tears than in stimulated tears. In stimulated tears the tissue plasminogen activator activity orginates mainly from the lacrimal gland. It is suggested that a constant concentration of plasminogen activator is released from the lacrimal gland and that this concentration is independent of the secretion rate of tear fluid and that the release from the conjunctiva is due to desquamation of cells.