Alden Chesney

Soluble CD200 Is Critical to Engraft Chronic Lymphocytic Leukemia Cells in Immunocompromised Mice

CD200 is a transmembrane molecule with an important immunoregulatory role that is overexpressed on most chronic lymphocytic leukemia (CLL) cells. In this study, we characterized a previously unknown soluble form of this molecule in human plasma termed sCD200. Levels of sCD200 were elevated in the plasma of patients with CLL as compared with healthy controls, and there was a significant correlation with CLL disease stage. Infusion of sCD200(hi) CLL plasma into severely immunocompromised NOD.SCIDγ(c)(null) (NSG) mice enhanced the engraftment of CLL splenocytes as compared with mice receiving sCD200(lo) normal plasma. CLL cells were detected in both the spleen and peritoneal cavity of animals for up to 75 days. Engraftment of CLL cells did not occur after infusion of CLL plasma depleted of sCD200 and was abolished in mice treated with anti-CD200 or OKT3 monoclonal antibody (mAb), suggesting a role for both sCD200 and T cells in CLL engraftment. Notably, anti-CD200 mAb was as effective as rituximab in eliminating engrafted CLL cells when administered 21 days after engraftment. Taken together, our findings point to sCD200 as a novel prognostic marker and therapeutic target for CLL. Furthermore, the humanized mouse model described here may prove valuable to preclinically assess new treatment regimens for CLL.

Estimating the prevalence of myelodysplastic syndromes in patients with unexplained cytopenias: a retrospective study of 322 bone marrows.

Although unexplained anemia is common in the elderly, the prevalence of MDS is poorly defined. We reviewed 2267 bone marrows reviewed at our center between the years 2002 and 2005. Of these, 322 met our criteria for inclusion (14%). Seventy-three patients (22.6%) had a confirmed diagnosis of MDS and 32 (9.9%) had suspected MDS. Confirmed or suspected MDS was more likely in patients aged >65 (31.5% and 11%, respectively). Age, MCV, LDH and RDW were independently predictive of MDS. Extrapolation of our findings to the elderly anemic individuals in the community suggests MDS prevalence may be higher than previously postulated.

Bone marrow aspirate and biopsy: a pathologist's perspective. II. interpretation of the bone marrow aspirate and biopsy.

Bone marrow examination has become increasingly important for the diagnosis and treatment of hematologic and other illnesses. Morphologic evaluation of the bone marrow aspirate and biopsy has recently been supplemented by increasingly sophisticated ancillary assays, including immunocytochemistry, cytogenetic analysis, flow cytometry, and molecular assays. With our rapidly expanding knowledge of the clinical and biologic diversity of leukemia and other hematologic neoplasms, and an increasing variety of therapeutic options, the bone marrow examination has became more critical for therapeutic monitoring and planning optimal therapy. Sensitive moleculartechniques, in vitro drug sensitivity testing, and a number of other special assays are available to provide valuable data to assist these endeavors. Fortunately, improvements in bone marrow aspirate and needle technology has made the procurement of adequate specimens more reliable and efficient, while the use of conscious sedation has improved patient comfort. The procurement of bone marrow specimens was reviewed in the first part of this series. This paper specifically addresses the diagnostic interpretation of bone marrow specimens and the use of ancillary techniques. J. Clin. Lab. Anal. 23:259–307, 2009.

Lenalidomide and metronomic melphalan for CMML and higher risk MDS: A phase 2 clinical study with biomarkers of angiogenesis

Metronomic, low dose chemotherapy may have anti-angiogenic effects and augment the effects of lenalidomide in MDS and CMML. We evaluated the clinical efficacy, tolerability and anti-angiogenic effects of melphalan 2mg and lenalidomide 10mg for 21 days/28 in CMML (n=12) and higher risk MDS (n=8) patients in a prospective phase II study. The primary endpoint was overall response and secondary endpoints included survival, progression-free survival, toxicity and biomarkers of angiogenesis. The median age was 73 years, 55% were pretreated and transfusion dependent. The overall response rate was 3(15%) of 19 evaluable patients but 25% in CMML and 33% in pCMML. Dose reductions and/or delays were common due to myelosuppression. Transient spikes in circulating endothelial cells that declined below baseline were seen in responders and patients with CMML, suggesting anti-angiogenic activity. In conclusion, lenalidomide and metronomic low dose melphalan demonstrate signals of clinical and possible anti-angiogenic activity in patients with pCMML that require future validation. This trial was registered at clinicaltrial.gov under # NCT00744536.

Validation of a scoring system to establish the probability of myelodysplastic syndrome in patients with unexplained cytopenias or macrocytosis.

Myelodysplastic syndromes (MDS) are clonal hematopoietic stem cell disorders primarily seen in the elderly that are characterized by ineffective hematopoiesis and a propensity to develop AML. Clinicians may be hesitant to refer older patients with unexplained cytopenias and/or macrocytosis for a bone marrow biopsy (BM), and consequently undiagnosed patients may be deprived access to effective treatments. Previously, we described factors which were independently predictive of a diagnosis of MDS at time of bone marrow: age ≥65, mean cell volume (MCV), red cell distribution width (RDW), and lactate dehydrogenase (LDH), and suggested a scoring system to calculate the post-test probability of MDS [1]. In this study we validate this scoring system in a cohort of 313 individuals who underwent bone marrow examinations for the investigation of unexplained cytopenias and or macrocytosis over a 3 year period at our institution (2006-2008). Thirty-two percent of all patients were diagnosed with MDS and 9% had suspected MDS. The post-test likelihood of a diagnosis of MDS increased from 12% when none of the four identified factors were present to 48% when 3 or more factors were present. This scoring system can be used to guide the diagnostic testing of patients presenting with unexplained cytopenias or macrocytosis.

Overexpression of Arginase 1 is linked to DNMT3A and TET2 mutations in lower-grade myelodysplastic syndromes and chronic myelomonocytic leukemia

Immune dysregulation is a common feature of myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CMML), particularly in early stages. However, the genetic basis remains poorly understood. We recently reported that macrophages from mice deficient in tet methylcytosine dioxygenase 2 (Tet2), a model of MDS/CMML, are hyperinflammatory and have increased expression of arginase 1 (Arg1). In macrophages and myeloid derived suppressor cells (MDSCs) expression of Arg1 contributes to T-cell suppression and immune evasion by L-arginine depletion, in the setting of chronic inflammation and cancer. Since human MDS and CMML are driven by TET2 mutations and associated with chronic inflammation, we hypothesized that arginase enzymatic activity and ARG1 expression would be increased in human MDS/CMML bone marrow. Elevated arginase activity was observed in bone marrow mononuclear cells of MDS and CMML patients with lower-grade features. Immunohistochemical studies confirmed that myelomonocytic cells overexpress ARG1. Additionally, mutations in the epigenetic regulators TET2 and DNMT3A corresponded to high ARG1 expression and activity. These findings suggest ARG1 is a biomarker of immune dysregulation in early MDS and CMML. Recent murine findings have implicated Tet2 and Dnmt3a in regulation of innate immunity. Our study suggests similar changes may be driven by human TET2 and DNMT3A mutations.

Fluorosis detected by trephine biopsy.

A 45-year-old man presented with low back pain and difficulty ambulating. A magnetic resonance imaging scan of the brain and lumbosacral spine demonstrated homogeneous replacement of normal marrow and routine chest radiograph revealed diffuse osteosclerosis (top left). He was referred to rule out an infiltrative marrow process. Iliac crest biopsy demonstrated normal trilineage haematopoeisis with markedly sclerotic cortical bone and thickened bony trabeculae (top right). There was no evidence of metastatic cancer or granulomatous disease. Bone mineral density Z-scores of lumbar spine and femoral neck were +10Æ8 and +10Æ9 respectively, confirming osteosclerosis. On further history, the patient admitted to ingesting five tubes of toothpaste per week for 30 years. Serum fluoride level was 44Æ2 lmol/l (reference 1Æ0–4Æ6 lmol/l), supporting a diagnosis of skeletal fluorosis. Skeletal fluorosis is caused by excessive fluoride ingestion. Although under-recognized in developed nations, it affects millions worldwide due to contaminated well water. Moderate exposure leads to dental effects such as staining and pitting of teeth and damage to enamel (bottom). Long-term ingestion may lead to skeletal abnormalities including debilitating arthralgias and impairment of cervical and lumbar mobility. Symptoms have been reported to resolve slowly after removal of fluoride.