Factor V activity in apheresis platelets: Implications for management of FV deficiency.

BACKGROUND: Allogeneic platelet (PLT) infusion is a strategy to raise Factor V (FV) levels in patients with congenital FV deficiency. However, since FV is labile in vitro, we hypothesized that FV activity could be low in PLT units. STUDY DESIGN AND METHODS: FV activity was tested using a prothrombin time-based platform in the supernatant and platelet lysate (PL) of apheresis PLT units (16 units stored in PLT additive solution with acetate and phosphate [PAS-C] and 10 units stored in plasma only), on post-collection days 3-6. Statistical analysis was performed using Student's t test (P < .05). RESULTS: FV activity was severely diminished in PAS-C PLTs (N = 16) supernatant (3.70% ± 1.02%) and PL (3.26% ± 1.02%). FV activity in plasma-only PLTs (N = 10) was lower in both supernatant (44.55% ± 6.46%) and lysate (39.67% ± 6.33%) relative to normal plasma levels, but both were significantly higher (P < .0001) compared to PAS-C PLTs. In a separate set of experiments, FV activity in PAS-C PLTs examined serially over storage time (N = 3 for these experiments) showed that FV levels were reduced by day 3 and not significantly different by day 5 of storage (Day 3 supernatant 5.03% ± 1.41%; Day 5 supernatant: 3.10% ± 0.57%; P = .2; Day 3 lysate: 3.89% ± 1.03%; Day 5 lysate: 2.61% ± 0.41%; P = .4). CONCLUSION: Plasma should be considered over PLTs as first-line therapy for non-complex FV deficiency-associated hemorrhage. If PLTs are considered for transfusion, plasma-only PLT units should be preferentially utilized, as PAS-C PLT have near-absent FV activity.

Characterization of circulating and cultured Tfh-like cells in sickle cell disease in relation to red blood cell alloimmunization status.

BACKGROUND: People living with sickle cell disease (SCD) are prone to red blood cell (RBC) alloimmunization. We hypothesized that subjects with alloantibodies (responders) would have differences in circulating T-follicular helper (Tfh)-like cells compared to subjects without alloantibodies (non-responders). MATERIALS AND METHODS: Peripheral blood mononuclear cells were collected from 28 subjects, including those with SCD and controls. Circulating CD4 T-cell subsets were first evaluated at baseline. CD4 T-cell subsets were also evaluated after naïve CD4 T-cells were differentiated into Tfh-like cells following in vitro culture with CD3/CD28 beads, IL-7, IL-12, and Activin A. Transfusion and alloantibody histories were extracted from the electronic medical record. RESULTS: Non-responders had a lower percentage of CD45RA negative Tmemory cells than responders or controls (p<0.05). Notably, there were no differences in circulating Tfh-like cells between any group. However, naïve CD4 T-cells from subjects with SCD were more likely to express CXCR5 after in vitro culture than cells from controls. After culture, CXCR5 expressing cells from responders were more likely to express PD1 and ICOS (16.43 %, sd. 20.23) compared to non-responders (3.69 %, s.d. 3.09) or controls (2.78 %, s.d. 2.04). DISCUSSION: The tendency for naïve CD4 T-cells from responders to differentiate into Tfh-like cells after in vitro culture may suggest these cells are prepared to assist B-cells with antibody production regardless of antigen specificity. Further studies are needed, but it is possible that these results may explain why some responders form RBC alloantibodies with multiple specificities, in addition to RBC autoantibodies and HLA alloantibodies.

Red blood cell alloimmunization is associated with lower expression of FcγR1 on monocyte subsets in patients with sickle cell disease.

BACKGROUND: Despite the clinical significance of red blood cell (RBC) alloantibodies, there are currently no laboratory tests available to predict which patients may be at risk of antibody formation after transfusion exposure. Given their phagocytic and inflammatory functions, we hypothesized that differences in circulating monocytes may play a role in alloimmunization. STUDY DESIGN AND METHODS: Forty-two adults with sickle cell disease (SCD) were recruited, with data extracted from the electronic medical record and peripheral blood analyzed by flow cytometry for total monocytes, monocyte subsets (CD14 high/CD16 low+ classical monocytes, CD14 high/CD16 high+ intermediate monocytes, and CD14 intermediate/CD16 high+ non-classical/inflammatory monocytes), and FcγR1 (CD64) expression. Thirteen "non-responder" patients (non-alloimmunized patients with documented RBC transfusion at the study institution) were compared to 20 alloimmunized "responder" patients, who had a total of 44 RBC alloantibodies identified. RESULTS: There were no significant differences in the percentages of total monocytes, monocyte subsets, or measured cytokines between non-responders and responders. However, non-responders had higher CD64 expression on classical monocytes (MFI mean 3424 ± standard deviation 1141) compared to responders (MFI mean 2285 ± 1501), p = 0.029, and on intermediate monocytes (MFI mean 3720 ± 1191) compared to responders (MFI mean 2497 ± 1640), p = 0.033. CONCLUSIONS: Monocytes and the inflammatory milieu increasingly are being appreciated to play a role in some complications of SCD. The differences in FcγR1 expression on monocyte subsets noted between responders and non-responders, which cannot be directly explained by the serum cytokines evaluated, warrant further investigation.

Delayed haemolytic and serologic transfusion reactions: pathophysiology, treatment and prevention.

PURPOSE OF REVIEW: The aim of this study was to summarize the basic epidemiology, pathophysiology and management of delayed serologic and delayed haemolytic transfusion reactions (DHTRs), as well as recent developments in our understanding of these adverse events. RECENT FINDINGS: Several studies have identified risk factors for DHTRs, including high alloantibody evanescence rates among both general patient groups and those with sickle cell disease (SCD). Antibody detection is also hampered by the phenomenon of transfusion record fragmentation. There have also been enhancements in understanding of what may contribute to the more severe, hyperhaemolytic nature of DHTRs in SCD, including data regarding 'suicidal red blood cell death' and immune dysregulation amongst transfusion recipients with SCD. With growing recognition and study of hyperhaemolytic DHTRs, there have been improvements in management strategies for this entity, including a multitude of reports on using novel immunosuppressive agents for preventing or treating such reactions. SUMMARY: Delayed serologic and haemolytic reactions remain important and highly relevant transfusion-associated adverse events. Future directions include further unravelling the basic mechanisms, which underlie DHTRs and developing evidence-based approaches for treating these reactions. Implementing practical preventive strategies is also a priority.

Antigen modulation as a potential mechanism of anti-KEL immunoprophylaxis in mice.

Red blood cell (RBC) alloimmunization is a serious complication of transfusion or pregnancy. Despite the widespread use of Rh immune globulin to prevent pregnancy associated anti-D alloimmunization, its mechanism of action remains elusive. We have previously described a murine model in which immunoprophylaxis with polyclonal anti-KEL sera prevents alloimmunization in wild-type recipients transfused with transgenic murine RBCs expressing the human KEL glycoprotein. To investigate the mechanism of action, we have now evaluated the outcome of immunoprophylaxis treatment in mice lacking Fcγ receptors (FcγRs), complement (C3), both, or none. Whereas polyclonal anti-KEL sera completely prevented alloimmunization in wild-type and single-knockout (KO) mice lacking FcγRs or C3, double-KO mice lacking both FcγRs and C3 became alloimmunized despite immunoprophylaxis. Rapid clearance of essentially all transfused RBCs with detectable KEL glycoprotein antigen occurred within 24 hours in wild-type and single-KO recipients treated with immunoprophylaxis, with the transfused RBCs remaining in circulation having minimal KEL glycoprotein antigen detectable by flow cytometry or western blot. In contrast, transfused RBCs with the KEL glycoprotein antigen fully intact continued to circulate for days in double-KO mice despite treatment with immunoprophylaxis. Further, in vitro phagocytosis assays showed no consumption of opsonized murine RBCs by double-KO splenocytes. Taken in combination, our data suggest that modulation of the KEL antigen (and potentially RBC clearance) by redundant recipient pathways involving both FcγRs and C3 may be critical to the mechanism of action of polyclonal anti-KEL immunoprophylaxis. These findings could have implications for the development of immunoprophylaxis programs in humans.

Be careful of the masquerades: differentiating secondary myelodysplasia from myelodysplastic syndromes in clinical practice.

In patients suspected to have myelodysplastic syndrome (MDS), especially in those patients without cytogenetic abnormalities or blast excess, accurate morphologic review by an expert hematopathologist and meticulous exclusion of other secondary causes of myelodysplasia are vital to establish the diagnosis. Errors in diagnosis can lead to dangerous consequences such as the administration of hypomethylating agents, lenalidomide, or even the use of intensive chemotherapy or allogeneic hematopoietic cell transplantation in patients who do not have an underlying MDS or even a malignant hematopoietic process. Additionally, beyond the possible harm and lack of efficacy of such therapies if the diagnosis of MDS is erroneous, the secondary myelodysplasia and resultant cytopenias are not likely to resolve unless the underlying etiology is identified and addressed. Discriminating a malignant process such as MDS from non-malignant secondary myelodysplasia can be quite challenging, and community hematologists/oncologists should consider referral to specialized physicians (both clinical experts and experienced hematopathologists) if there is any doubt regarding the diagnosis. In this article, we present a representative case series of patients from our own practice who posed diagnostic dilemmas and propose a systematic approach for assessment for secondary causes of myelodysplasia.

Hemoglobinopathy Screening in a 15-Year-old Patient With Anemia.

Identification of hemoglobinopathies in pediatric patients can be challenging and has important implications for the patient, as well as family members. Laboratory identification of uncommon hemoglobin (Hb) variants can pose a significant problem. Although many Hb variants can be largely identified using conventional electrophoresis and HPLC, confirmatory Hb DNA analysis may be necessary. This report provides an example of a pediatric patient with a complex heterozygous Hb by electrophoresis and HPLC, which necessitated identification by DNA analysis. Clinical and laboratory scenarios warranting Hb DNA analysis are additionally discussed.

Molecular findings in myeloid neoplasms.

The proliferation of new molecular technologies in recent years has greatly advanced our knowledge of the genetics that underlie hematologic cancers. Particularly, with the advent and wide-implementation of next-generation sequencing (NGS), a host of somatic (and some germline) gene mutations have been identified as significant in the classification, prognostication, and treatment of the spectrum of myeloid neoplasms. These driver and disease modifier mutations now play a prominent role in the updated international diagnostic guidelines of acute myeloid leukemia (AML), myelodysplastic syndromes/neoplasms (MDS), and myeloproliferative neoplasms (MPN). As high-throughput technologies such as NGS increasingly become standard in the genetic evaluation of myeloid disorders, it is critical that clinicians understand the clinical relevance of these mutations in order to further personalize patient care. In this review we discuss some of the most essential somatic and cytogenetic findings.

Molecular Techniques and Gene Mutations in Myelodysplastic Syndromes.

Sequencing technology, particularly next-generation sequencing, has highlighted the importance of gene mutations in myelodysplastic syndromes (MDSs). Mutations affecting DNA methylation, chromatin modification, RNA splicing, cohesin complex, and other pathways are present in most MDS cases and often have prognostic and clinical implications. Updated international diagnostic guidelines as well as the new International Prognostic Scoring System-Molecular incorporate molecular data into the diagnosis and prognostication of MDS. With whole-genome sequencing predicted to become the future standard of genetic evaluation, it is likely that MDS diagnosis and management will become increasingly personalized based on an individual's clinical and genomic profile.

Diagnosis and Classification of Myelodysplastic Syndromes with Mutated TP53.

The genetic underpinnings of myeloid neoplasms are becoming increasingly well understood. The accessibility to sequencing technology, in particular next-generation sequencing (NGS), has highlighted the importance of gene mutations in myelodysplastic syndromes (MDS) in conjunction with traditional cytogenetics. With the relatively recent influx of molecular information to complement known cytogenetic abnormalities, the diagnosis, classification, and prognosis of MDS and acute myeloid leukemia (AML) have been increasingly refined, which has also led to therapeutic advancements. It has been shown that TP53 mutations have a significant impact in cases of MDS, as well as AML, and have led to TP53-defined myeloid disease. TP53 mutations are also now incorporated into prognostic scoring systems, as patients have been shown to have aggressive disease and poor outcomes. With the increased understanding of the importance of TP53 disruption in myeloid neoplasia, it is likely that the critical role of TP53 will continue to be highlighted by an individual's disease classification and personalized therapeutic management.

Helicobacter pylori-negative mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach: A clinicopathologic analysis.

OBJECTIVES: Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is historically associated with Helicobacter pylori (HP) infections in more than 80% of patients. However, the incidence of HP-negative MALT lymphoma has been increasing. The clinicopathologic features have not been well studied, and optimal management strategies remain unclear. METHODS: The pathology database was searched for primary gastric MALT lymphomas diagnosed from 2000 to 2017. The clinical data and the slides were reviewed. The cases were divided for analysis into those with a background of chronic gastritis with HP, chronic gastritis without HP, and without either a background of chronic gastritis or HP. RESULTS: Of 70 gastric MALT lymphoma cases identified, 26 (37% of total) had chronic gastritis and were positive for HP histologically (n = 23) or were HP positive by additional laboratory testing (n = 3). The remaining 44 (63% of total) cases were HP negative by histology. Within the HP-negative cases, 5 (11% of HP-negative cases) showed histologic gastritis while 39 (89% of HP-negative cases) did not have sufficient evidence of gastritis through review of slides (n = 18) or based on available pathology reports (n = 21). The HP-negative cases without gastritis had higher propensities to show a mass lesion on endoscopy compared with HP-positive cases (37.5% vs 11.1%, P = .02) at the initial diagnosis. The immunophenotype and rate of positive B-cell gene rearrangement were not significantly different between the 2 groups. While all HP-positive patients received antibiotics for HP eradication, treatment in the HP-negative group varied among antibiotics, radiation, rituximab, or chemotherapy. Among HP-negative patients with available follow-up, 13 (39%) showed disease recurrence, similar to the recurrence rate in HP-positive patients; however, no individual from either group has died of the disease thus far. CONCLUSIONS: The incidence of HP-negative MALT lymphoma is increasing, and in our practice, it is currently more common than HP-associated MALT lymphomas. The pathophysiology of HP-negative MALT lymphoma without chronic gastritis remains unclear. Follow-up data in our study suggest that the prognosis of these cases is excellent despite varied management modalities.

Quantitative Risk for Single-Positive Lupus Anticoagulant Results With Different Anticoagulants.

OBJECTIVES: Clinical experts recommend against testing for lupus anticoagulant (LAC) during anticoagulation. METHODS: We quantitated the risk of a single-positive dilute Russell viper venom time (dRVVT) result or partial thromboplastin time-based phospholipid neutralization (PN) result on anticoagulation. RESULTS: Any anticoagulation led to a fourfold greater likelihood of single-positive results, primarily by rivaroxaban (odds ratio [OR] = 8.6) and warfarin (OR = 6.6), resulting in a positive dRVVT test with a normal PN test. Heparin and apixaban were twofold more likely to show single-positive results, but enoxaparin did not show significant single positivity. CONCLUSIONS: Our results quantitatively support experts' avoidance of LAC testing during anticoagulation.

Optimizing Donor Chimerism Threshold for Next-Generation Sequencing Monitoring of Measurable Residual Disease Post-Allogeneic Stem Cell Transplantation for Myeloid Neoplasms.

Next-generation sequencing (NGS) is used to monitor genetically measurable residual disease (gMRD) following allogeneic stem cell transplantation (aSCT). It is unknown whether an upper limit of chimerism exists such that gMRD NGS testing can be safely forgone. We reviewed 61 patients with acute myeloid leukemia and 24 patients with myelodysplastic syndrome who had at least 1 NGS panel before and after aSCT between 2016 and 2020. Donor chimerism was quantified. Logistic regression characterized which factors predicted gMRD. Receiver operating characteristic (ROC) curves were used to determine the optimal chimerism threshold for which gMRD would not be detected. Data from an additional 22 patients with follow-up NGS testing in 2022 were also analyzed to validate our proposed threshold. A: s expected, donor chimerism was a significant predictor of gMRD (odds ratio, .38; 95% confidence interval, .10 to .62; P = .02). Age, sex, conditioning regimen, presence of a related donor, and diagnosis were not associated with gMRD. A chimerism threshold of 92.5% optimized sensitivity (97.7%) and specificity (95.4%) such that values >92.5% strongly predicted the absence of gMRD (area under the ROC curve [AUC], .986). The validation cohort demonstrated similarly strong predictive capability (AUC, .974) with appropriate sensitivity (100%) and specificity (90.9%). NGS monitoring of gMRD is redundant at chimerism values greater than a more conservative threshold of 92.5% after aSCT.