The alkaline phosphatases comprise a heterogeneous group of enzymes that are widely distributed in mammalian cells. They often are associated with cell membranes, but their exact physiologic function is unknown. Despite this, alkaline phosphatase activity is a very useful serum biochemical indicator of liver disease, particularly cholestatic disease. However, increases in the activity of alkaline phosphatase in serum and other body fluids may reflect physiologic or pathologic changes beyond those of hepatic origin. For example, nonhepatic increases in serum alkaline phosphatase activity are found in young animals, in pregnant and lactating females, and in association with high fat diets. Bone disease, endocrine disease, neoplasia, and other disorders can result in increased alkaline phosphatase activity. In addition, alkaline phosphatase activity may be increased due to induction by certain drugs such as glucocorticoids and anticonvulsants. In this article, we will review the physiologic and pathologic factors influencing the activity of alkaline phosphatase in serum and other body fluids, with an emphasis on disorders beyond liver disease. (Vet Clin Pathol. 2007;36:223-233)

Abstract. Immunohistochemical and histochemical stains are useful adjunct techniques in the diagnosis of canine cutaneous round cell tumors, which can appear histologically similar. We applied a panel of monoclonal antibodies (recognizing tryptase, chymase, serotonin for mast cells; CD1a, CD18, MHC class II for histiocytes; CD3 for T lymphocytes; CD79a for B lymphocytes and plasma cells) and one histochemical stain (naphthol AS-D chloroacetate for chymase activity) to formalin-fixed, paraffin-embedded sections of canine cutaneous mast cell tumors, histiocytomas, lymphosarcomas, plasmacytomas, and unidentified round cell tumors. Of 21 tumors with a histologic diagnosis of mast cell tumor, 7/7 (100%) grade I, 6/7 (85.7%) grade II, and 3/7 (42.9%) grade III tumors were diagnosed as mast cell tumors based on positive staining for tryptase antigen and chymase activity. Mast cells were positive for both tryptase antigen and chymase activity, indicating equal efficacy of tryptase immunohistochemistry and chymase histochemistry. Chymase was detected immunohistochemically in both tumor and nontumor cells, while serotonin was not detected in most mast cell tumors, and thus, neither was useful in the diagnosis of mast cell tumors. Immunohistochemistry to detect CD18 and MHC class II was equally effective in staining histiocytomas, although lymphosarcoma must be ruled out through the use of CD3 and CD79a immunohistochemistry. Immunohistochemistry using three different monoclonal antibodies to human CD1a showed no cross-reactivity in canine histiocytomas and was not useful. A final diagnosis was obtained for 4/5 (80%) of the unidentified tumors, indicating the usefulness of multiple stains in poorly differentiated round cell tumors.

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Prevalence of MLAI was high in this population. Although the RSQ did not allow differentiating normal horses from horses with MLAI, it has a high sensitivity to detect horses with SLAI and is therefore a good screening tool for SLAI.

Enumeration of mast cells is unreliable when the standard 400-cell differential counting method is used, whereas the 5-field method on slides with higher cell density reached acceptable reproducibility. Neutrophil percentages were highly reliable with both methods.

BackgroundBand cells and toxic neutrophils are thought to indicate acute and severe systemic illness but no studies have investigated their importance in adult equine emergency admissions.ObjectivesThe objective of this study was to evaluate the association of band cells and toxic neutrophils with systemic inflammatory response syndrome (SIRS) and outcome in horses.AnimalsOne hundred and five adult horses admitted on emergency basis to a private primary referral practice.MethodsProspective observational study with sample collection. All horses admitted on emergency basis over the study period were included in the study if they had a CBC and a blood smear collected on admission.ResultsThe detection of band neutrophils on admission was associated with the SIRS status of the horse (RR = 2.80; 95% CI = 1.57–4.99; P < .001) and with poor outcome (RR = 1.88; 95% CI: 1.05–3.37; P = .038). Similarly, the presence of a neutrophil toxic grade higher than 3 was associated with SIRS (RR = 1.71; 95% CI: 1.03–2.82; P = .034) and death (RR = 2.34; 95% CI: 1.22–4.50, P = .007). The information gained from the blood smear review could not be captured by looking at only the WBC or neutrophil count.Conclusions and Clinical ImportanceThe microscopic review of blood smears from critically ill horses to detect band cells or neutrophil toxic change is valuable and could help in assessing disease severity and prognosis in adult equine emergency admissions.

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Ultrastructural and immunohistochemical studies on tissues from five patients with Argentine hemorrhagic fever revealed previously undetected lesions caused by the viral infection. Two types of particle were seen in the cells of all organs examined. The particles had some characteristics similar to those described for arenaviruses. However, the virus-like particles were intracellular, had a single membrane, and apparently originated by a process of budding into the endoplasmic reticulum cisternae. Intranuclear bodies and three types of cytopolasmic change were observed in conjunction with the virus-like particles; Antigenic determinants of Junin virus were demonstrated in cells of all organs examined. Immunohistochemical experiments also indicated alterations in the cellular mechanisms of protein synthesis. Until now the pathogenesis of human diseases produced by arenaviruses has not been established. The results of this study suggest that in Argentine hemorrhagic fever the virus is responsible for a direct pathogenic action.