Snyders, C. I. | Search bioRxiv

bioRxiv2019

Immunoglobulin profile and B-cell frequencies are altered with changes in the cellular micro-environment independent of the stimulation conditions

B-cells are essential in the defense against Mycobacterium tuberculosis. Studies on isolated cells may not accurately reflect the responses that occur in vivo due to the presence of other cells. This study elucidated the influence of microenvironment complexity on B-cell polarisation and function in the context of TB disease. B-cell function was tested in whole blood, PBMCs and as isolated cells. The different fractions were stimulated and the B-cell phenotype and immunoglobulin profiles analysed. The immunoglobulin profile and killer B-cell frequencies varied for each of the investigated sample types, while in an isolated cellular environment, secretion of immunoglobulin isotypes IgA, IgG2 and IgG3 was hampered. The differences in the immunoglobulin profile highlight the importance of cell-cell communication for B-cell activation. In contrast, increased frequencies of killer B-cells were observed following cellular isolation, suggesting a biased shift in augmented immune response in vitro. This suggests that humoral B-cell function and development was impaired likely due to a lack of co-stimulatory signals from other cell types. Thus, B-cell function should ideally be studied in a PBMC or whole blood fraction.

immunology↗

bioRxiv2019

Potential of host serum protein biosignatures in the diagnosis of tuberculous meningitis in children

BackgroundTuberculous meningitis (TBM) is the most severe form of tuberculosis and results in high morbidity and mortality in children. Diagnostic delay contributes to the poor outcome. There is an urgent need for new tools for the rapid diagnosis of TBM, especially in children.\n\nMethodsWe collected serum samples from children in whom TBM was suspected at a tertiary hospital in Cape Town, South Africa. Children were subsequently classified as having TBM or no TBM using a published uniform research case-definition. Using a multiplex cytokine array platform, we investigated the concentrations of serum biomarkers comprising 7-markers that were previously found to be of value in the diagnosis of adult pulmonary TB (CRP, SAA, CFH, IFN-{gamma}, IP-10, Apo-AI and transthyretin) plus other potentially useful host biomarkers as diagnostic candidates for TBM.\n\nFindingsOf 47 children included in the study, 23 (48.9%) had a final diagnosis of TBM of which six had HIV co-infection. A modified version of the adult 7-marker biosignature in which transthyretin was replaced by NCAM1, diagnosed TBM in children with AUC of 0.80 (95% CI, 0.67-0.92), sensitivity of 73.9% (95% CI, 51.6-89.8%) and specificity of 66.7% (95% CI, 44.7-84.4%). A new childhood TBM specific 3-marker biosignature (adipsin, A{beta}42 and IL-10) showed potential in the diagnosis of TBM, with AUC of 0.84 (95% CI, 0.73-0.96), sensitivity of 82.6% (95 CI, 61.2-95.0%) and specificity of 75.0% (95% CI, 53.3-90.2%) after leave-one-out cross validation.\n\nConclusionAn adult 7-marker serum protein biosignature showed potential in the diagnosis of TBM in children. However, a smaller childhood TBM-specific biosignature demonstrated improved performance characteristics. Our data indicates that blood-based biomarkers may be useful in the diagnosis of childhood TBM and require further investigation.

immunology↗