The spectrum of hemophagocytic lymphohistiocytosis: a retrospective study comparing adult macrophage activation syndrome to malignancy-associated hemophagocytic lymphohistiocytosis.

Secondary hemophagocytic lymphohistiocytosis (sHLH) is a life-threatening inflammatory syndrome that can be triggered by autoimmune diseases, malignancy, or infection. In rheumatologic patients, sHLH is referred to as macrophage activation syndrome (MAS). Differentiating between triggers is important for prompt treatment and prognosis. Data comparing subsets of sHLH are limited due to the rarity of this disease. We aim to explore differences in clinical features that may differentiate MAS from malignancy-associated HLH (mHLH) patients. We conducted a single-center retrospective study assessing clinical characteristics, laboratory parameters, treatment regimens and outcomes in 34 patients with sHLH over a 16 year period. We compared patients with MAS to those with mHLH. Hepatomegaly was not present in the MAS group but was present in the mHLH group (0 vs. 25%, p = 0.024). MAS patients had on average nearly double the concentration of platelets at 50.0 (IQR: 31.0-78.0 Kµ/L) vs. 29.0 Kµ/L (IQR: 14.0-37.5 Kµ/L), p = 0.003. Soluble IL-2R concentrations were four times lower in the MAS group with a median soluble IL-2R concentration of 6814.5 kU/L (IQR: 2101-2610 kU/L) vs. 27972.0 kU/L (IQR: 12,820-151,650 kU/L), p = 0.010. The MAS group fared better overall than the mHLH group but was not statistically significant (mortality 22 vs. 44%, p = 0.18). MAS and mHLH patients exhibited different laboratory parameters and clinical features, most notably differences in platelet counts, soluble IL-2R concentration and hepatomegaly, which may help differentiate these conditions early in their course.

nimO, an Aspergillus gene related to budding yeast Dbf4, is required for DNA synthesis and mitotic checkpoint control.

The nimO predicted protein of Aspergillus nidulans is related structurally and functionally to Dbf4p, the regulatory subunit of Cdc7p kinase in budding yeast. nimOp and Dbf4p are most similar in their C-termini, which contain a PEST motif and a novel, short-looped Cys2-His2 zinc finger-like motif. DNA labelling and reciprocal shift assays using ts-lethal nimO18 mutants showed that nimO is required for initiation of DNA synthesis and for efficient progression through S phase. nimO18 mutants abrogated a cell cycle checkpoint linking S and M phases by segregating their unreplicated chromatin. This checkpoint defect did not interfere with other checkpoints monitoring spindle assembly and DNA damage (dimer lesions), but did prevent activation of a DNA replication checkpoint. The division of unreplicated chromatin was accelerated in cells lacking a component of the anaphase-promoting complex (bimEAPC1), consistent with the involvement of nimO and APC/C in separate checkpoint pathways. A nimO deletion conferred DNA synthesis and checkpoint defects similar to nimO18. Inducible nimO alleles lacking as many as 244 C-terminal amino acids supported hyphal growth, but not asexual development, when overexpressed in a ts-lethal nimO18 strain. However, the truncated alleles could not rescue a nimO deletion, indicating that the C terminus is essential and suggesting some type of interaction among nimO polypeptides.