Circadian and Interpersonal Variability of Iga in Nasal Secretions

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Abstract
Secretory immunoglobulin-A (IgA) in nasal mucus exerts a major protective function for the respiratory tract, and low amounts of IgA are reported to correlate with susceptibility to disease. Therefore, a study has been made of the variability in amount of IgA present in human nasal mucosa. Subjects' IgA production has been found to vary substantially during the day and to reach very low values from time to time. Subjects sampled themselves by a nasal wash procedure. The samples were analyzed for IgA and for total soluble protein Because the total protein is relatively constant, use of the ratio of these two quantities reduces the effect of sampling differences and gives a better measure of IgA production. Samples were collected five and six times daily in November and March. The results were similar with no seasonal effect. A three- to four-fold change was found in the IgA production of most subjects during an average day. The peak usually appeared between midnight and 8:00 a.m., with a broad low period during the afternoon, displaying a typical circadian cycle. The greatest number of low-value samples appeared in the period between 2:00 and 5:00 p.m. Subjects differed in their average level of IgA production. Most subjects had periods of consecutive low samples, often showing that their IgA production was low for four or more hours. All subjects had some periods of low IgA production. Some were consistently low, and these reported having a higher incidence of respiratory disease than average. These low periods and the variation between subjects may be important as to the susceptibility to respiratory disease. The method of determination is well worked out. It is recommended that physicians utilize this analysis to help diagnose the patient with frequent respiratory sickness, including those of the bronchial mucosa, sinus and middle ear. The present study shows that a serial observation of four samples over the day would be best for finding a hypo condition. However, if only one sample can be taken, the later part of the afternoon is the best time in order to discover the deficiency, if any. The existence of a circadian cycle suggests possible control by the adrenal hormone system which has a similar cycle. If confirmed by further research this finding would point to a study of methods of treatment to increase IgA production.

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