Considerations for the use of salivary IgA for monitoring mucosal immune function.

INTRODUCTION: We aimed to make recommendations concerning the use of total IgA in saliva (s-IgA) as an aid for monitoring athletic and military training. METHODS: Unstimulated whole saliva was collected from 16 subjects (11 women and 5 men ages 18-57) during nonconsecutive days of fasting and non-fasting. Seven samples were collected from each subject at 0700, 0900, 1200, 1400, 1600, 1800, and 2030 on each day and a further three samples were collected 30 min after three meals on the non-fasting day (at 0730, 1230, and 1830). Strenuous activity was avoided and subjects did not drink caffeine or alcohol-containing beverages. Albumin and s-IgA were measured by commercial nephelometric immunoassays with intra-analytical coefficient of variance (CVA) of 1.8% and 2.9%, respectively. Individual and group variations were determined. Diurnal variation was determined by use of repeated-measures analysis of variance. RESULTS: CV-individual (CV(I)) was 48% for s-IgA concentration and 43% for s-IgA secretion and s-IgA:albumin. CV-group (CVG) for these same measures was 68%, 75%, and 68%, respectively. When measurements were adjusted for saliva flow rates there was no evidence that s-IgA is subject to diurnal variation. There was strong evidence for a postprandial decrease in s-IgA for all measures. CONCLUSION: The high degree of individuality in s-IgA precludes the use of population reference ranges for identifying individual abnormal results. For the purpose of monitoring individuals we recommend using the individual's calculated biological variance (determined from previous serial measurements over a period of days to weeks). Individual abnormal results can then be identified.

Australian army recruits in training display symptoms of overtraining.

The proposition that the demands of recruit training, including physical and psychological stresses, result in symptoms of overtraining was investigated during the 45-day Army Common Recruit Training course. Body mass, physical fitness, fasting blood measures of immune status, hormones (serum free testosterone/cortisol ratio), inflammation, and iron status were measured at baseline and after weeks 5 and 6. Psychological measures of mood and fatigue and general health were measured at the end of each week. Sleep diaries were completed each evening and morning. Evidence for overtraining symptoms of fatigue, sleep disturbance, immune suppression, reduced iron status, high rates of minor injuries, and hormonal changes was found. However, recruits were not pushed so hard that physical performance deteriorated greatly. Accumulated sleep deprivation might be a major contributor to the adverse hormonal changes. We conclude that there was some evidence of recruits being overtrained.

The physiological and psychological effects of combat ration feeding during a 12-day training exercise in the tropics.

The health and psychological effects of combat ration pack (CRP) feeding during 12 days of military training in a tropical environment were investigated. Three groups of air defence guards (ADGs) received either: freshly prepared foods (fresh group, 15 mega joule (MJ), 3,600 kcal, N=13), full CRP (15 MJ, 3,600 kcal, N=10), or one-half CRP (7.5 MJ, 1,800 kcal, N=10). Underconsumption by the full CRP group resulted in CRP groups experiencing similar weight loss, protein catabolism, and immune suppression (both cell-mediated and humoral), whereas the fresh group maintained their weight and protein balance and cell-mediated immune status. CRP groups reported greater fatigue than the fresh group. All ADGs experienced poor sleep quality and declining folate and iron status. ADGs drank insufficient water to prevent dehydration. In the medium term, ADGs were able to adapt to restricted food consumption and poor sleep quality with no decrement in physical fitness or cognition.

Measurement of immunoglobulin A in saliva by particle-enhanced nephelometric immunoassay: sample collection, limits of quantitation, precision, stability and reference range.

BACKGROUND: Total immunoglobulin A in saliva (s-IgA) is normally assayed using an enzyme-linked immunosorbent assay. We have investigated methodological issues relating to the use of particle-enhanced nephelometric immunoassay (PENIA) to measure s-IgA in whole unstimulated saliva and determine its reference range. METHODS: Whole unstimulated resting saliva was collected to determine sample stability (temperature, time, effect of a protease inhibitor), limit of quantitation (LOQ), assay precision and analytical variation. The reference range for 134 healthy adults was determined. RESULTS: Linearity was excellent (4-10.3 mg L(-1), P < 0.001; R(2) = 0.997) and without significant bias (mean of -0.7%). The lowest intra- and inter-analytical coefficients of variation were 1.8% and 7.5% and LOQ was 1.4 mg L(-1). The concentration of s-IgA is stable at room temperature for up to 6 h, at 4 degrees C for 48 h, at -4 degrees C for two weeks and at -80 degrees C for up to 1.3 yr. There is no evidence that a protease inhibitor increases the stability or that repeated freeze-thawing cycles degrade sample quality. The reference ranges for s-IgA concentration, s-IgA secretion, s-IgA:albumin and s-IgA:osmolality were 15.9-414.5 mg L(-1), 7.2-234.9 microg min(-1), 0.4-19 and 0.6-8.9, respectively. CONCLUSION: Automated PENIA assay of s-IgA is precise and accurate. High stability of collected saliva samples and the ease and speed of the assay make this an ideal method for use in athletic and military training situations. The convenience of measuring albumin and IgA on the same analytical platform adds to the practicability of the test.