title: Salivary Immunoglobulin A Secretion Rate Is Negatively Associated with Cancer Mortality: The West of Scotland Twenty-07 Study.
abstract: Immunoglobulins are essential for combating infectious disease although very high levels can indicate underlying pathology. The present study examined associations between secretory immunoglobulin A (sIgA) in saliva and mortality rates in the general population. Participants were 639 adults from the eldest cohort of the West of Scotland Twenty-07 Study aged 63 years at the time of saliva sampling in 1995. From unstimulated 2-minute saliva samples, saliva volume and S-IgA concentration were measured, and S-IgA secretion rate determined as their product. Mortality data were tracked for 19 years. Cox proportional hazard models were applied to compute hazard ratios (HR) for all-cause mortality from sIgA secretion rate. Associations were adjusted for gender, assay batch, household occupational group, smoking, medication usage, and self-reported health. There was a negative association between log sIgA secretion rate and all-cause mortality, HR = 0.81, 95%CI = 0.73-0.91, p < .001. Further analysis of specific causes of mortality revealed that the all-cause association was due to an underlying association with cancer mortality and in particular with cancers other than lung cancer. The HR for non-lung cancer was 0.68 (95%CI = 0.54 to 0.85) implying a 32% reduction in mortality risk per standard deviation rise in log sIgA secretion rate. Effects were stronger for men than women. For deaths from respiratory diseases, sIgA secretion had a non-linear relationship with mortality risk whereby only the very lowest levels of secretion were associated with elevated risk. SIgA concentration revealed a similar but weaker pattern of association. In the present study, higher secretion rates of sIgA were associated with a decreased risk of death from cancer, specifically non-lung cancer, as well as from respiratory disease. Thus, it appears that sIgA plays a protective role among older adults, and could serve as a marker of mortality risk, specifically cancer mortality.
authors.affiliation: School of Sport, Exercise & Rehabilitation Sciences, University of Birmingham, Birmingham, England.
authors.forename: Anna C
authors.initials: AC
authors.lastname: Phillips
authors.affiliation: School of Sport, Exercise & Rehabilitation Sciences, University of Birmingham, Birmingham, England.
authors.forename: Douglas
authors.initials: D
authors.lastname: Carroll
authors.affiliation: Clinical Immunology Service, College of Medicine and Dentistry, University of Birmingham, Birmingham, England.
authors.forename: Mark T
authors.initials: MT
authors.lastname: Drayson
authors.affiliation: MRC/CSO Social and Public Health Sciences Unit, University of Glasgow, Glasgow, Scotland.
authors.forename: Geoff
authors.initials: G
authors.lastname: Der
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis*; D005260:Female; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000032:analysis / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology / Q000378:metabolism / Q000401:mortality*; D011379:Prognosis; D012463:Saliva / Q000737:chemistry / Q000378:metabolism*; D012606:Scotland / Q000453:epidemiology; D012636:Secretory Rate; D015996:Survival Rate
chemical_list: D015415:Biomarkers; D007071:Immunoglobulin A, Secretory