JAK2 exon 12 mutations define a distinctive myeloproliferative syndrome that affects patients who currently receive a diagnosis of polycythemia vera or idiopathic erythrocytosis.

A murine monoclonal antibody specific for calf intestinal alkaline phosphatase has been prepared and used in an unlabeled antibody bridge technique for labeling monoclonal antibodies. This procedure-the alkaline phosphatase monoclonal anti-alkaline phosphatase (APAAP) method-gives excellent immunocytochemical labeling of tissue sections and cell smears, comparable in clarity and intensity to that achieved with immunoperoxidase labeling. If the enzyme label is developed with a naphthol salt as a coupling agent and Fast Red or hexazotized new fuchsin as a capture agent, a vivid red reaction product is obtamed which is very easily detected by the human eye. For this reason the APAAP technique was found particularly suitable for labeling cell smears (for both cytoplasmic and surface-membrane antigens) and for detecting low num-APAAP 220 CORDELL ET AL APAAP STAINING OF MONOCLONAL ANTIBODIES

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The number and volume of cells in the blood affect a wide range of disorders including cancer and cardiovascular, metabolic, infectious and immune conditions. We consider here the genetic variation in eight clinically relevant hematological parameters, including hemoglobin levels, red and white blood cell counts and platelet counts and volume. We describe common variants within 22 genetic loci reproducibly associated with these hematological parameters in 13,943 samples from six European population-based studies, including 6 associated with red blood cell parameters, 15 associated with platelet parameters and 1 associated with total white blood cell count. We further identified a long-range haplotype at 12q24 associated with coronary artery disease in 9,479 cases and 10,527 controls. We show that this haplotype demonstrates extensive disease pleiotropy, as it contains known risk loci for type 1 diabetes, hypertension and celiac disease and has been spread by a selective sweep specific to European and geographically nearby populations.

Activating mutations of MPL exon 10 have been described in a minority of patients with idiopathic myelofibrosis (IMF) or essential thrombocythemia (ET), but their prevalence and clinical significance are unclear. Here we demonstrate that MPL mutations outside exon 10 are uncommon in platelet cDNA and identify 4 different exon 10 mutations in granulocyte DNA from a retrospective cohort of 200 patients with ET or IMF. Allelespecific polymerase chain reaction was then used to genotype 776 samples from patients with ET entered into the PT-1 studies. MPL mutations were identified in 8.5% of JAK2 V617F ؊ patients and a single V617F ؉ patient. Patients carrying the W515K allele had a significantly higher allele burden than did those with the W515L allele, suggesting a functional difference between the 2 variants. Compared with V617F ؉ ET patients, those with MPL mutations displayed lower hemoglobin and higher platelet levels at diagnosis, higher serum erythropoietin levels, endogenous megakaryocytic but not erythroid colony growth, and reduced bone marrow erythroid and overall cellularity. Compared with V617F ؊ patients, those with MPL mutations were older with reduced bone marrow cellularity but could not be identified as a discrete clinicopathologic subgroup. MPL mutations lacked prognostic significance with respect to thrombosis, major hemorrhage, myelofibrotic transformation or survival. (Blood.