Performance of an expanded salivary IgA method to assess sIgA as a biomarker of stress-induced immunomodulation.
Henningsen-G; Hurrell-J; Baker-F; Douglas-C; Baumgardner-E; MacKenzie-B; Roberston-S; Phipps-F; Biagini-RE
Toxicologist 1994 Mar; 14(1):27
Salivary immunoglobulin A (sIgA) is an attractive biomolecule from the aspect of non-invasively obtaining potential human biomarkers of exposure to immunomodulating agents or of effects by correlating results with systemic immune function. Salivary samples can be readily obtained in frequent and large amounts without pain or much inconvenience. SlgA is more stable than other potential salivary biomolecules, such as cortisol or catecholamine. An ELISA (enzyme linked immunosorbent assay) was modified to sensitively and specifically quantify both total and specific human IgA. The ELISA was used to evaluate weekly slgA levels in 40 premenopausal nurses over 32 weeks. Monthly blood samples were drawn for comprehensive immunocompetency and clinical hematology tests. As part of a NIOSH study to evaluate occupational stress, weekly and monthly questionnaires on subjective and objective stressors were also given to the study participants for use in correlating bioassay results with stress. The antigen tested for specific slgA was LPS (lipopolysaccharide) from five strains of E. coli. Total protein levels and salivary flow rates (ml of saliva in 5 minutes) were measured for use in correcting slgA results. The total slgA ELISA was calibrated for each weekly run with 8 standards of human colostrum IgA ranging from 2.5 to 50 mg%, and excellent reproducibility was obtained (+/-3mg%). Endpoint titers were measured as two-fold serum dilutions between 1:10 and 1:640, but more variability was observed (+/- 0.9 of a two-fold endpoint titer). The corrected (protein and flow) slgA ELISA assay was sufficiently sensitive, accurate and precise to differentiate between groups of high vs low stress subjects.
Immunological-tests; Immunology; Immunoglobulins; Analytical-processes; Biomarkers; Immune-reaction; Health-care-personnel; Job-stress; Nursing
The Toxicologist. Society of Toxicology 33rd Annual Meeting, March 13-17, 1994, Dallas, Texas