Identification of a nonlysozymal bactericidal factor (beta lysin) in human tears and aqueous humor

Our plain-English summary of Identification of a nonlysozymal bactericidal factor (beta lysin) in human tears and aqueous humor, by L.C. Ford, R.J. DeLange, R.W. Petty (American Journal of Ophthalmology, 1976).

The study

• Authors: L.C. Ford, R.J. DeLange, R.W. Petty
• Journal: American Journal of Ophthalmology
• Published: 1976;81(1):30-3
• Cited by: 32 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

An antibacterial factor, identical with or closely related to beta lysin, was measured in human tears, in human aqueous humor, and in fractions of each fluid after an absorption step involving cellulose-asbestos filters. Antibeta lysin was used to help distinguish whether bactericidal activity was due to lysozyme or beta lysin. Beta lysin activity was found in both human tears and aqueous humor in higher amounts than were present in serum; appreciable amounts of lysozyme were found in human tears but not in aqueous humor. Beta lysin is a normal constituent of human tears and aqueous humor and its role in these fluids is that of an antibacterial agent that may also act in concert with lysozyme to destroy bacteria in tears.

In plain English

This laboratory study was not about asbestos as a health hazard. Asbestos appears only as the material of cellulose-asbestos filters used to split eye fluids into fractions. The authors tested whether a germ-killing substance in human tears other than lysozyme was beta lysin, and whether it was also in aqueous humor, the fluid inside the eye. Tears came from 100 healthy volunteers aged 16 to 50, and aqueous humor from 15 cataract surgery patients aged 60 to 70. Whole tears had 32 to 64 units of bactericidal activity. Adding antibody against beta lysin cut this to 8 units. Whole aqueous humor had 2 to 4 units of activity while its lysozyme was below 0.5 μg/ml, and the antibody abolished detectable activity. The authors concluded that beta lysin, or a closely related substance, is a normal part of human tears and aqueous humor and acts as an antibacterial agent. They noted that their method could not fully separate lysozyme from beta lysin.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory study measuring antibacterial factors in human eye fluids
• Who was studied: Tears from 100 healthy volunteers aged 16 to 50 years, and aqueous humor collected during cataract surgery from 15 patients aged 60 to 70 years. The article does not state where or when the samples were collected.
• Exposure: No asbestos exposure was studied. Cellulose-asbestos filters were used only as a laboratory tool to separate tears and aqueous humor into a filtrate fraction and an absorbed fraction.
• Main results:
  • In whole tears, the egg-white lysozyme equivalent was 100 to 150 μg/ml and bactericidal activity was 32 to 64 units.
  • When antibody to beta lysin was added to whole tears, bactericidal activity fell to 8 units. This is the same level obtained with egg-white lysozyme alone at 100 μg/ml.
  • The absorbed fraction of tears contained 11 to 15 μg/ml of lysozyme and had 8 units of activity. Adding antibeta lysin lowered this to 2 units. The authors stated that lysozyme alone did not account for all the bactericidal activity of tears.
  • Whole aqueous humor had 2 to 4 units of bactericidal activity, with lysozyme below 0.5 μg/ml (the assay's lower limit).
  • Antibeta lysin added to whole aqueous humor or to its absorbed fraction abolished detectable bactericidal activity. The authors attributed the activity in aqueous humor to beta lysin or a closely related substance, not to lysozyme.
• The authors' conclusion: The authors concluded that beta lysin, or a substance immunologically related to it, is a normal part of human tears and aqueous humor. They concluded it acts as an antibacterial agent that may also work together with lysozyme in tears.
• Limitations the authors state:
  • The purification method could not completely separate lysozyme from beta lysin.
  • The clinical importance of beta lysin in tears or aqueous humor was not known.

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• Distribution of transforming growth factor-beta 1, fibronectin, and smooth muscle actin in asbestos-induced pulmonary fibrosis in rats — T.D. Perdue, A.R. Brody (1994)
• Reduced tumor necrosis factor-alpha and transforming growth factor-beta1 expression in the lungs of inbred mice that fail to develop fibroproliferative lesions consequent to asbestos exposure — D.M. Brass, G.W. Hoyle, et al. (1999)

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