Non-invasive and label-free identification of human natural killer cell subclasses by biophysical single-cell features in microfluidic flow.

Natural killer (NK) cells are indicated as favorite candidates for innovative therapeutic treatment and are divided into two subclasses: immature regulatory NK CD56bright and mature cytotoxic NK CD56dim. Therefore, the ability to discriminate CD56dim from CD56bright could be very useful because of their higher cytotoxicity. Nowadays, NK cell classification is routinely performed by cytometric analysis based on surface receptor expression. Here, we present an in-flow, label-free and non-invasive biophysical analysis of NK cells through a combination of light scattering and machine learning (ML) for NK cell subclass classification. In this respect, to identify relevant biophysical cell features, we stimulated NK cells with interleukine-15 inducing a subclass transition from CD56bright to CD56dim. We trained our ML algorithm with sorted NK cell subclasses (≥86% accuracy). Next, we applied our NK cell classification algorithm to cells stimulated over time, to investigate the transition of CD56bright to CD56dim and their biophysical feature changes. Finally, we tested our approach on several proband samples, highlighting the potential of our measurement approach. We show a label-free way for the robust identification of NK cell subclasses based on biophysical features, which can be applied in both cell biology and cell therapy.

Expression profile of HLA-B*38:55Q allele.

The identification of null or questionably expressed HLA allelic variants is a major issue in HLA diagnostics, because the mistyping of the aberrant expression of such alleles can have a major impact on the outcome of both hematopoietic stem cell transplantation (HSCT) and solid organ transplants. It is debated how questionable (Q) alleles, because of their unknown expression profile, should be considered in an allogenic HSCT setting. The HLA-B*38:55Q allele was detected as an HLA-B blank specificity; DNA sequencing identified a single polymorphism at position 373 in exon 3 (TGC > CGC), which results in the replacement of cysteine 101 with an arginine in the HLA-B heavy chain, thus, impairing disulfide bridge formation in the alpha-2 domain, essential for the normal expression of the HLA molecules. In order to determine the RNA and protein expression profile of this allelic variant, we analyzed antigenic expression at different levels, transcriptional and transductional, using a combination of cellular methods, such as serological testing and flow cytometric analysis, polymerase chain reaction (PCR) sequence-specific primer (SSP) cDNA group-specific amplification and immunocytochemical assay, demonstrating the prevalent cytoplasmatic distribution of the HLA-B*38:55Q protein. Our findings suggest that in matching process the HLA-B*38:55Q allele needs to be considered as a low expressed allele, able to elicit an allogenic T-cell response in vivo and impair the transplant outcome.

Hypereosinophilia in childhood acute lymphoblastic leukaemia at diagnosis: report of 2 cases and review of the literature.

Hypereosinophilia as first clinical presentation has rarely been reported in paediatric acute lymphoblastic leukaemia. It is commonly associated with specific cytogenetic abnormalities. Although eosinophilia is considered a reactive, non-neoplastic epiphenomenon, it adversely affects patient outcomes, both in children and adults. We describe herewith two paediatric patients who had marked eosinophilia at onset of acute lymphoblastic leukaemia. We point out the importance of a correct differential diagnosis in persistent, unexplained peripheral hypereosinophilia. Clinicians should keep in mind that eosinophilia can be part of the overall pattern of acute leukaemia and therefore needs to be properly investigated. We also provide some recommendations for an appropriate approach to hypereosinophilia - related morbidities.

Phenotypic APC resistance as a marker of hypercoagulability in primitive cerebral lymphoma.

UNLABELLED: Thrombosis is the most frequent complication and the second cause of death in patients with malignant disease. Primary central nervous system non-Hodgkin's lymphoma represents a rare pathology. Resistance to APC is usually linked to a factor V (FV) gene mutation changing an Arg 506 to a Gln in the APC cleavage site. AIM: In our study, we aimed at investigating the presence of activated protein C resistance (APC-r) and other markers of hypercoagulability in 25 selected patients with a diagnosis of primitive cerebral lymphoma who had suffered from an ischemic episode of TIA and/or stroke. PATIENTS AND METHODS: 25 selected patients with a diagnosis of primitive cerebral lymphoma and 50 healthy subjects acted as control group, were tested. We measured APC-r, natural clotting inhibitors, F1 + 2, aPTT and PAI-1 according to international guidelines. Genomic DNA was extracted from peripheral white blood cells and in order to detect FV Leiden gene polymorphism. RESULTS: Our results showed that 11 out of 25 patients had a poor response to APC (< or = 0.70, which represents the cut-off point in our general population) without deficiencies in natural clotting inhibitors. All patients had high plasma levels of F1+2 and PAI-1 compared to those found in healthy subjects (2.65 +/- 0.75 nM/L vs 0.40 +/- 0.35 nM/L; 67.5 +/- 18.5 ng/mL vs 17 +/- 11.5 ng/mL, respectively). In 9 patients resistance to APC was not associated to a FV gene defect demonstrating that such phenomenon may occur also as an acquired condition. However, the patients with resistance to APC showed the highest plasma values in F1 + 2 and PAI-1. CONCLUSION: In cerebral lymphoma with hypercoagulability the resistance to APC is not caused by the FV Arg 506-->Gln mutation (82%). APC resistance not caused by this FV gene defect may be an additional risk factor for thrombophilia in this selected population.

Molecular characterization of a factor VII deficient patient supports the importance of the second epidermal growth factor-like domain.

BACKGROUND AND OBJECTIVES: Although a large number of gene mutations have been characterized in patients with factor VII (FVII) deficiency, few naturally occurring mutations have been described in epidermal growth factor (EGF)-like domains. We investigated a 6-year old Italian girl who had low functional and antigenic FVII plasma levels. DESIGN AND METHODS: Plasma levels of FVII activity and antigen were evaluated in the propositus and her relatives. Mutation screening was performed by sequencing the FVII gene. The effect of the identified FVII mutations was investigated by protein expression in transfected cells. RESULTS: The propositus was shown to be a compound heterozygote for a known (Arg110Cys) and a novel (Asp123Tyr) missense mutation both occurring in the second EGF-like domain. In transfected cells, expression of the Arg110Cys mutation reduced the amount of intracellular and secreted FVII protein (48% and 18%, respectively). Likewise, cells transfected with the Asp123Tyr mutation gave rise to low intracellular (40%) and extracellular (4%) FVII antigen levels. In conditioned media, FVII procoagulant activity was reduced accordingly (10% and <1%, respectively). INTERPRETATION AND CONCLUSIONS: Transient expression of the identified FVII mutations caused severely reduced but detectable FVII antigen and activity levels. The present findings suggest that the two naturally occurring missense mutations identified within the second EGF-like domain severely affect FVII protein handling, impairing the correct folding of FVII.