Early Interferon-γ Production in Human Lymphocyte Subsets in Response to Nontyphoidal Salmonella Demonstrates Inherent Capacity in Innate Cells

Background Nontyphoidal Salmonellae frequently cause life-threatening bacteremia in sub-Saharan Africa. Young children and HIV-infected adults are particularly susceptible. High case-fatality rates and increasing antibiotic resistance require new approaches to the management of this disease. Impaired cellular immunity caused by defects in the T helper 1 pathway lead to intracellular disease with Salmonella that can be countered by IFNγ administration. This report identifies the lymphocyte subsets that produce IFNγ early in Salmonella infection. Methodology Intracellular cytokine staining was used to identify IFNγ production in blood lymphocyte subsets of ten healthy adults with antibodies to Salmonella (as evidence of immunity to Salmonella), in response to stimulation with live and heat-killed preparations of the D23580 invasive African isolate of Salmonella Typhimurium. The absolute number of IFNγ-producing cells in innate, innate-like and adaptive lymphocyte subpopulations was determined. Principal Findings Early IFNγ production was found in the innate/innate-like lymphocyte subsets: γδ-T cells, NK cells and NK-like T cells. Significantly higher percentages of such cells produced IFNγ compared to adaptive αβ-T cells (Student's t test, P<0.001 and ≤0.02 for each innate subset compared, respectively, with CD4+- and CD8+-T cells). The absolute numbers of IFNγ-producing cells showed similar differences. The proportion of IFNγ-producing γδ-T cells, but not other lymphocytes, was significantly higher when stimulated with live compared with heat-killed bacteria (P<0.0001). Conclusion/Significance Our findings indicate an inherent capacity of innate/innate-like lymphocyte subsets to produce IFNγ early in the response to Salmonella infection. This may serve to control intracellular infection and reduce the threat of extracellular spread of disease with bacteremia which becomes life-threatening in the absence of protective antibody. These innate cells may also help mitigate against the effect on IFNγ production of depletion of Salmonella-specific CD4+-T lymphocytes in HIV infection

Salivary Immunoglobulin A Secretion Rate Is Negatively Associated with Cancer Mortality: The West of Scotland Twenty-07 Study

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

The utility of saliva for the assessment of anti-pneumococcal antibodies: investigation of saliva as a marker of antibody status in serum

Context: Salivary antibodies may act as non-invasive marker of systemic immunity enabling assessment of vaccination and protection against bacterial infections. Objective: To assess if levels of anti-pneumococcal (Pn) antibodies in saliva reflect concentrations in serum and determine whether saliva can accurately identify protective concentrations in serum. Methods: IgG, IgA and IgM antibody levels in paired saliva and serum samples were measured against 12 Pn polysaccharide antigens in 72 healthy adults. Results: Antibody levels in saliva correlated positively with serum across immunoglobulin classes, most strongly for IgA. Individuals who had protective antibody levels in serum demonstrated significantly higher IgG and IgA salivary antibody concentrations/secretion rates. Salivary IgG and IgA Pn antibodies were able to distinguish between those with/without protective levels in serum for the majority of serotypes. Salivary IgM antibodies were not able to differentiate protective status. Median IgG and IgA Pn salivary parameters were able to identify individuals who had protective levels in serum on ≥8/12 serotypes with moderate accuracy: median IgA secretion rates provided the best sensitivity (73%) and specificity (71%). Conclusions: These findings suggest that IgG and IgA Pn specific antibodies in saliva may be useful surrogate markers of antibody status in serum

Serum free light chains are reduced in endurance trained older adults: Evidence that exercise training may reduce basal inflammation in older adults

Traditionally, free light chains (FLCs) are used as key serum biomarkers in the diagnosis and monitoring of plasma cell malignancies, but polyclonal FLCs can also be used as an accurate real-time indicator of immune-activation and inflammation. The primary aim of the present study was to assess the effects of exercise training status on serum FLCs in older adults, and secondly, to examine if training status moderated serum FLC responses to acute exercise. Kappa and lambda serum FLC levels were measured in 45 healthy older adults (aged ≥ 60 years) who were either sedentary, physically active or endurance trained. FLCs were measured at baseline and in response to an acute bout of submaximal exercise. The endurance trained group had significantly lower levels of kappa and lambda serum FLCs compared with physically active or sedentary elderly adults; these effects were independent of age, BMI and renal function. There was no significant difference in whole immunoglobulins between groups. Exercise training status had no effect on serum FLC responses to acute exercise, which were marginal. In conclusion, endurance training was associated with lower FLC levels compared with less physically active individuals. These findings suggest that long-term endurance training may be beneficial in reducing basal inflammation in older adults as well as elevated FLCs present in inflammatory and autoimmune conditions, often associated with ageing. FLCs may serve as a useful biomarker for monitoring the efficacy of exercise intervention studies in healthy and clinical populations

Salivary free light chains as a new biomarker to measure psychological stress: the impact of a university exam period on salivary immunoglobulins, cortisol, DHEA and symptoms of infection:the impact of a university exam period on salivary immunoglobulins, cortisol, DHEA and symptoms of infection

Introduction: Measurement of immunoglobulin free light chains (FLCs) in saliva can serve as a non-invasive biomarker in health and behavioural research. FLCs have been explored in relation to physiological stress but FLC responses to psychological stress and their relationship with infections remain unknown. This study aimed to investigate the impact of exam period stress on salivary FLCs alongside other established biomarkers of stress and whether FLCs relate to symptoms of infection. Methods: 58 healthy adults studying at university completed saliva samples and questionnaires in a period without exams (baseline), and again prior to the start of an exam period. Saliva samples were assessed for FLCs, IgA, cortisol and dehydroepiandrosterone (DHEA). Measures of life events stress, perceived stress, anxiety and depression were completed. Students also reported incidence and severity of symptoms of infection and rated general well-being at baseline, prior to, during and after the exam period. Exercise, sleep and alcohol consumption were also assessed at both timepoints. Results: FLCs secretion rates were significantly lower at the exam period compared to baseline (p &lt;.01), with reductions of 26% and 25% for κ FLC and λ FLC, respectively. In agreement, salivary IgA secretion rate was lower at exams (non-significant trend, p =.07). Cortisol concentration significantly increased at exams (p &lt;.05) while DHEA did not change, leading to an increase in the cortisol:DHEA ratio (p =.06). Depression (p &lt;.05) and anxiety increased from baseline to exams and life stress reported in the build up to the exam period was higher compared with baseline (p &lt;.001). Well-being significantly decreased from baseline to exams (p &lt;.01). The proportion of participants reporting infection symptoms (70%) was unchanged between baseline and prior to exams. No significant relationships were found between FLCs or other saliva parameters and infection symptoms, well-being or stress/psychological measures. Changes in saliva parameters between timepoints were independent of health behaviours. Conclusions: Salivary FLCs are responsive to life events stress and corroborate with IgA. This preliminary study highlights the potential utility of FLCs as a new salivary biomarker in stress research.</p

Exercise Selectively Mobilises Skin-Homing Effector CD8+ T Cells and Natural Killer Cells into Peripheral Blood.

Introduction: Acute exercise induces a transient mobilisation of lymphocyes into peripheral blood that is largely comprised of CD8+ T cells and natural killer (NK) cells. The magnitude of this response is dependent on the differentiation status of these lymphocyte subsets, thus cells with a capacity to initiate rapid effector function (i.e., cytokine secretion and target killing) exhibit the largest changes in response to exercise. It is hypothesised that the effector cells preferentially mobilised into the bloodstream have high tissue-migrating potential, however, the origin of these cells, and their potential homing destination(s) following exercise has not been established in humans. Accordingly, this study investigated whether CD8+ and NK cell subsets expressing the cutaneous lymphocte antigen (CLA) – a molecule expressed on skin-associated memory lymphocytes (≤ 20% CD8+ T cells and ≤ 50%NK cells) that binds to endothelial cell leukocyte adhesion molecule 1 (ELAM-1) – were selectively mobilised in response to acute exercise. Methods: Ten healthy males (mean ± SD age: 22 ± 3 yrs) completed two different exercise sessions: high-intensity continuous cycling (CC; 85% at HRPeak for 30 mins) and high-intensity interval training (HIIT; 90% of HRpeak 10 x 1 min repetitions with 1 min rest intervals). Blood was taken before, immediately- and 30 min post-exercise for cryo-preservation of peripheral blood mononuclear cells. CD8+ subsets were classified into naive (NA; CD45RA+CCR7+), central memory (CM; CD45RA−CCR7+), effector-memory (EM; CD45RA−CCR7−) and CD45RA- expressing effector-memory cells (EMRA; CD45RA+CCR7−). In parallel, CD56bright ‘regulatory’ and CD56dim ‘cytotoxic’ NK subsets were identified using CD56 and CD16. Lymphocyte subpopulations were examined for CLA expression. Results: The number of CLA+CD8+ cells increased in response to both exercise modes. This observation was driven by a preferential mobilisation of effector-memory CLA+CD8+ T cells, as shown by the percentage change in cell number from baseline to exercise: EMRA (CC 244%, HIIT 86%) \u3e EM (CC 142%, HIIT 75%) \u3e CM (CC 104%, HIIT 51%) \u3e naive (CC 82%, HIIT 34%). Within the NK cell pool, CLA+CD56dim cells (CC 520%, HIIT 326%) were mobilised to a greater extent than CLA+CD56bright cells (CC 180%, HIIT 129%). 30-min post-exercise, there was a reduction in the number of CLA+ cells compared to pre-exercise values. Conclusion: This is the first study to demonstrate a selective mobilisation of skin-homing lymphocytes during exercise, suggesting that exercise redistributes effector cells to peripheral tissue, contributing to immune-surveillance

Analytical validation of new ELISAs for the quantitation of polyclonal free light chains and comparison to existing assays for healthy and patient samples

Background: Polyclonal FLCs can be used as a biomarker of inflammation and immune activation in a range of diseases. This study evaluated the performance of new FLC ELISAs (Seralite FLC ELISA) for the quantitation of polyclonal κ and λ FLC, including comparisons to existing assays. Methods: Technical performance was assessed for the ELISA and reference ranges were generated using healthy donor serum (N = 91). Patients with a range of conditions associated with polyclonal FLC dysregulation (N = 164) were measured across platforms. Results: The ELISAs generated references ranges of: 8.72–23.0 mg/L κ FLC, and 8.52–25.24 mg/L for λ FLC. ELISAs demonstrated linearity across the calibration range and intra-assay (≤ 8.7%) and inter-assay (≤ 12.3%) imprecision was low. The limit of detection was 0.63 mg/L for κ and 0.57 mg/L for λ FLC. Minimal cross-reactivity was observed for interference agents, alternate FLC and whole immunoglobulin (median change ≤3.6 mg/L). Assays showed good batch-to-batch consistency. For patient samples, methods generated different κ and λ FLC concentrations and differences were seen between methods for the number of patients classified as below, with and above references ranges for κ and λ FLC. There was no significant difference in the FLC sum between the different techniques. Conclusions: The ELISAs displayed good analytical and technical performance. The quantification of individual κ and λ FLC appears inherently different between platforms. These differences are attenuated if using the FLC sum, which was similar between methods and provided agreement in relation to patients having normal or elevated FLCs.</p