Serum Immunoglobulins, Pneumonia Risk, and Lung Function in Middle-Aged and Older Individuals: A Population-Based Cohort Study

Abstract

IntroductionImmunoglobulins (Igs) play a pivotal role in host defense and prevention of pneumonia. Aging influences serum Ig levels, but the association between Igs and pneumonia in community-dwelling older individuals remains unknown. We evaluated the association of serum IgA, IgG, and IgM with pneumonia and lung function in middle-aged and older individuals.MethodsWe performed Cox and negative binomial regression analyses for the association of Igs with incident pneumonia and pneumonia-related mortality, and recurrent pneumonia respectively. We performed logistic regression analyses for the association between Igs and lung function values. Associations were adjusted for age, sex, smoking, comorbidities, and serum C-reactive protein.ResultsWe included 8,766 participants (median age 62.2 years, 57% women, median follow-up 9.8 years). Higher IgA (hazard ratio [HR]: 1.15; 95% confidence interval [95% CI]: 1.00-1.32) and IgG (HR: 1.13; 95% CI: 1.06-1.19) were associated with an increased pneumonia risk. Higher IgG was associated with an increased risk of pneumonia-related mortality (HR: 1.08; 95% CI: 1.01-1.16) and recurrent pneumonia (incidence rate ratio: 1.04; 95% CI: 1.00-1.09). Higher IgA and IgG were also associated with lower forced expiratory volume in one second (FEV1), lower forced vital capacity (FVC), and an increased odds of preserved ratio impaired spirometry (PRISm, i.e. FEV1 <80% and FEV1/FVC ratio ≥70%). No association was seen with an obstructive spirometry pattern.DiscussionHigher serum IgA and IgG levels were associated with pneumonia, pneumonia-related mortality, and PRISm in middle-aged and older individuals from the general population. Future studies should validate our findings and elucidate underlying pathophysiology.

Low and high serum IgG associates with respiratory infections in a young and working age population

“… 7 , 8 In addition, there is some evidence suggestive of unfavourable properties associated with high serum IgG concentration among older individuals. 9 Our lifelong follow-up study on the health of a young and working age birth cohort population and their serum IgG concentrations suggests novel insights into the significance of adaptive immunity. 10 , 11 Highly intriguingly, not only the low IgG but also high serum IgG concentration in our cohort are associated with unfavourable outcomes.…”

“… 7 , 8 Among older individuals, even high serum IgG has been associated with risk of pneumonia-related mortality and recurrent pneumonia. 9 At an unselected population level, however, the significance of serum IgG concentrations on respiratory infection burden among the young and working age population is incompletely understood.…”

The Relationship Between Human Host and Environmental Factors on the Severity of Pneumonia Among Under-Five Children in West Java Province

“…Reactions that occur due to decreased serum IgA levels can cause a decrease in the body's immunity which has an impact on respiratory tract disorders to exacerbate the degree of infection from pneumonia. 42 The limitation of the results of this study is that the sample size of children with LBW is too small so that it cannot represent the severity of pneumonia in West Java.…”

A new hope? Possibilities of therapeutic IgA antibodies in the treatment of inflammatory lung diseases

“…Diverging data regarding the serum immunoglobulin levels of pneumonia patients were published. Studies showed either lower ( 38 – 40 ) or higher ( 41 , 42 ) levels of IgA, nevertheless both were associated with an increased mortality risk. Data on alterations in mucosal antibody levels are scarce.…”