Common Infectious Agents and Monoclonal B-Cell Lymphocytosis: A Cross-Sectional Epidemiological Study among Healthy Adults

<div><h3>Background</h3><p>Risk factors associated with monoclonal B-cell lymphocytosis (MBL), a potential precursor of chronic lymphocytic leukaemia (CLL), remain unknown.</p> <h3>Methods</h3><p>Using a cross-sectional study design, we investigated demographic, medical and behavioural risk factors associated with MBL. “Low-count” MBL (cases) were defined as individuals with very low median absolute count of clonal B-cells, identified from screening of healthy individuals and the remainder classified as controls. 452 individuals completed a questionnaire with their general practitioner, both blind to the MBL status of the subject. Odds ratios (OR) and 95% confidence interval (CI) for MBL were estimated by means of unconditional logistic regression adjusted for confounding factors.</p> <h3>Results</h3><p>MBL were detected in 72/452 subjects (16%). Increasing age was strongly associated with MBL (P-trend<0.001). MBL was significantly less common among individuals vaccinated against pneumococcal or influenza (OR 0.49, 95% confidence interval (CI): 0.25 to 0.95; P-value = 0.03 and OR: 0.52, 95% CI: 0.29 to 0.93, P-value = 0.03, respectively). Albeit based on small numbers, cases were more likely to report infectious diseases among their children, respiratory disease among their siblings and personal history of pneumonia and meningitis. No other distinguishing epidemiological features were identified except for family history of cancer and an inverse relationship with diabetes treatment. All associations described above were retained after restricting the analysis to CLL-like MBL.</p> <h3>Conclusion</h3><p>Overall, these findings suggest that exposure to infectious agents leading to serious clinical manifestations in the patient or its surroundings may trigger immune events leading to MBL. This exploratory study provides initial insights and directions for future research related to MBL, a potential precursor of chronic lymphocytic leukaemia. Further work is warranted to confirm these findings.</p> </div

Odds ratios (OR) estimates, with 95% confidence intervals (CI), for “low-count” monoclonal B-cell lymphocytosis by self-reported family history of cancer.

<p>Ref: reference group; N: number; NA: not estimated; het: heterogeneity.</p><p>OR: Odds ratio; CI: confidence interval; 1^st degree relatives: parents, siblings and children; 2^nd degree relatives: grand-parents.</p>1<p>Adjusted for age (<50, 50–59, 60–69, 70+) and sex.</p>2<p>Further adjusted for family size (using the total number of children and siblings; categories: <6; 6 or more; missing).</p>3<p>Further adjusted for number of siblings (categories: <2; 3 or more; missing).</p>4<p>Further adjusted for number of children (<2; 3 or more; missing).</p>5<p>Adjusted for number of brothers (<3; 3 or more; missing).</p

Association of Locus-specific DNA methylation to aGVHD.

<p>(A) IFNγ methylation up to 12 months post-transplant is shown in the left panel. The black line marked the mean value in the cohort and the dotted line marked the mean value 1 month post-HCT. In the central panel are represented IFNγ methylation values according to severity of aGVHD 1 month post-HCT. IFNγ ROC curve for patients with severe aGVHD versus non-aGVHD and moderate aGVHD (AUC = 0.782) is shown in the right panel. (B) FASL methylation up to 12 months post-transplant and methylation values according to severity of aGVHD 1 month post-HCT. FASL ROC curve for patients with severe aGVHD versus non-aGVHD and moderate aGVHD (AUC = 0.769) is shown in the right panel. (C) IL-10 methylation up to 12 months post-transplant and methylation values according to severity of aGVHD 1 month post-HCT. IL-10 ROC curve for patient with and without aGVHD (AUC = 0.764) is shown in the right panel. (D) PRF1 methylation up to 12 months post-transplant and methylation values according to severity of aGVHD 1 month post-HCT.</p

Odds ratios for “low-count” monoclonal B-cell lymphocytosis by selected potential variables related to infectious agents.

<p>Ref: reference group; N: number; het: heterogeneity; OR: Odds ratio; CI: confidence interval ¹: Adjusted for age (<50, 50–59, 60–69, 70+) and sex ²: Further adjusted for family size (using the total number of children and siblings; categories: <6; 6 or more; missing). ³: Further adjusted for number of siblings (categories: <2; 3 or more; missing) <i>⁴:</i> Further adjusted for number of children (0/2; 3or more; missing) <i>⁵:</i> Adjusted for age (<70, 70+) and sex, N_controls = 189; N_cases = 59 P-values were calculated using Wald-test. Black squares indicate OR, the area of each square being proportional to the amount of statistical information contributed. Horizontal lines represent 95% CI.</p

Analysis of global DNA methylation levels post-HCT.

<p>(A) Diagram of the experimental design. The differences of the global methylation levels between donors, pre-HCT recipients and post-HCT recipients were assessed by a pyrosequencing based methylation assay of repetitive DNA elements (LINE1 and NBL2) in whole blood. (B) NBL2 ΔMet values between donors, pre-HCT recipients, and 1 month post-HCT recipients. (C) NBL2 ΔMet mean values between donors and recipients up to 12 months post-transplant. The dotted line marks the ΔMet mean value between donors and 1 month post-HCT recipients (ΔMet = 5.8450). During the follow up of the transplant, the mean values barely deviated from the initial post-HCT ΔMet. (D) LINE1 ΔMet values between donors, pre-HCT recipients and 1 month post-HCT recipients. (E) LINE1 ΔMet mean values between donors and recipients up to 12 months post-transplant. The dotted line marked the ΔMet mean value between donors and 1 month post-HCT recipients (ΔMet = 5.383).</p

Patient characteristics.

<p>Patient characteristics.</p

Changes in NBL2 methylation levels are associated to HCT outcomes.

<p>(A) NBL2 ΔMet between donors and 1 month post-transplant recipient with complete and mixed chimerism. (B) ROC curve for patients with complete and mixed chimerism (AUC = 0.911). (C) NBL2 ΔMet between donors and 1 month post-transplant recipients according to severity of aGVHD. (D) ROC curve for patients with severe aGVHD versus non-aGVHD and moderate aGVHD (AUC = 0.678).</p

Promoter DNA methylation profiling using bead arrays and differential methylation analysis after HCT.

<p>Scatter plots showing DNA methylation in donors versus post-transplant recipients 1 month and 6 months post-HCT. Red dots represent CpG sites with methylation values altered more than 20% relative to donor values.</p