5-year survival rate for childhood acute lymphoblastic leukemia (ALL) has risen to approximately 90%, yet the causal disease pathway is still poorly understood. Evidence suggests multiple 'hits' are required for disease progression; an initial genetic abnormality followed by additional secondary 'hits'. It is plausible that environmental influences may trigger these secondary hits, and with the peak incidence of diagnosis between 2 and 5 years of age, early life exposures are likely to be key. DNA methylation can be modified by many environmental exposures and is dramatically altered in cancers, including childhood ALL. Here we explore the potential that DNA methylation may be involved in the causal pathway toward disease by acting as a mediator between established environmental factors and childhood ALL development.

Summary The seasonal influenza A vaccine is recommended for patients with myeloproliferative neoplasms (MPNs). We hypothesised that immune deregulation associated with MPNs may affect the immune response gained following vaccinations when compared to healthy controls. Using deep immunophenotyping with high‐dimensional single‐cell analysis and mass cytometry we could demonstrate an altered immune response in MPN patients following vaccination. We found that prior to vaccination, MPN patients had reduced numbers of naive CD4 T cells. Furthermore, at 3‐weeks and 3‐months post‐vaccination there was evidence of both delayed and impaired B‐ and T‐memory cells responses. Thus, although, the immune systems of MPN patients can 'recognise' the Influenza A vaccine, the response appears inferior compared to healthy controls.

In myelodysplastic syndromes (MDS) the immune system is involved in pathogenesis as well as in disease progression. Dendritic cells (DC) are key players of the immune system by serving as regulators of immune responses. Their function has been scarcely studied in MDS and most of the reported studies didn’t investigate naturally occurring DC subsets. Therefore, we here examined the frequency and function of DC subsets and slan+ non-classical monocytes in various MDS risk groups. Frequencies of DC as well as of slan+ monocytes were decreased in MDS bone marrow (BM) compared to normal bone marrow (NBM) samples. Transcriptional profiling revealed down-regulation of transcripts related to pro-inflammatory pathways in MDS-derived cells as compared to NBM. Additionally, their capacity to induce T cell proliferation was impaired. Multidimensional mass cytometry showed that whereas healthy donor-derived slan+ monocytes supported Th1/Th17/Treg differentiation/expansion their MDS-derived counterparts also mediated substantial Th2 expansion. Our findings point to a role for an impaired ability of DC subsets to adequately respond to cellular stress and DNA damage in the immune escape and progression of MDS. As such, it paves the way toward potential novel immunotherapeutic interventions.