Factors influencing measurement of human salivary lysozyme in lysoplate and turbidimetric assays

Abstract

The use of different assay conditions has complicated the evaluation of studies relating salivary lysozyme levels to oral or systemic disease. The purpose of this study was to compare values obtained for lysozyme activity in mixed saliva of 104 healthy subjects by using two assay techniques and four variations in sample preparation. Lysozyme activity was assayed by the turbidimetric and lysoplate methods with human colostrum lysozyme as the standard. Lysozyme activity in saliva samples made 0.5 M with respect to NaCl was compared with that in untreated samples with and without centrifugation. Mean values for lysozyme concentration in centrifuged saliva were 2.2 pg/ml with the turbidimetric assay and 5.9 ,g/ml with the lysoplate assay. In samples which were salt treated before centrifugation, mean concentrations increased to 17.3 and 72.9 ,ug/ml, respectively. The results for uncentrifuged saliva were four to five times higher than the results for centrifuged saliva in each of the assay systems. Salt treatment without centrifugation produced values comparable to those obtained with centrifugation. The addition of salt to human colostrum or hen egg white lysozyme generally resulted in a 20 to 25% increase in expressed activity. These results indicate that (i) the measurement of lysozyme in the supernatant of centrifuged saliva is of questionable value, (ii) most of the lysozyme in whole saliva is inactive and may be activated by markedly increasing the ionic strength, and (iii) values for lysozyme activity in whole saliva are much greater in the lysoplate assay than in the turbidimetric assay when the same standard is used.

Evolutionary trade-offs associated with loss of PmrB function in host-adapted Pseudomonas aeruginosa

“…Lysozyme is abundant in the mammalian airway 16 and is active against both Gram-positive and Gram-negative species 17 , 18 . Significant differences in resistance between isolates were observed at lysozyme concentrations within the physiological range found in saliva 19 . Lysozyme resistance obtained through pmrB mutation may, therefore, provide a selective advantage in the establishment of respiratory tract infection.…”

Antimicrobial activities of human biofluids and their antimicrobial peptide fractions against Candida albicans

“…• for SA -defensin hβD-1 -10 µg/ml [11], secretory inhibitor of leucoprotease -18 µg/ml [12], lactoferrin -8 µg/ml [13], lysozyme -4 µg/ml [14], psoriasin -14 µg/ml [15] and histatin -33 µg/ml [16];…”

Nasal secretory response to allergen provocation

“…One possible explanation for this discrepancy comes from a study published after the completion of our data collection. Jenzano and colleagues noted that the enzymatic activity of salivary lysozyme varies considerably with how the sample is treated [15]; the addition of sodiuni chloride to 0-5 M increased the activity of lysozyme eight-to twelve-fold, and uncentrifuged saliva was four to five times more active than a centrifuged sample. Mucin-containing biological fiuids are quite complex in their physiochemical properties.…”