Spontaneous polar anterior subcapsular lenticular opacity in Sprague-Dawley rats.

A spontaneous focal polar anterior subcapsular lenticular opacity characterized by focal epithelial proliferation was found in Charles River Sprague-Dawley rats from various breeding facilities around the world (France, Japan, and the United States). The incidence of this change slightly increased with age up to a maximal incidence of 9.8% in 28- to 35-week-old male rats (French source). Over that period, there was little change in the size of the opacity; however some rats that were examined over longer periods (more than 2 years of age) developed secondary anterior cortical changes, and rarely, histologic findings of pigmentation and/or mineralization. The lenticular change was present throughout the life of the animals and had no sex predilection; mode of inheritance was not investigated. Due to its small size, this lens opacity is more easily identified by use of slit lamp biomicroscopy than by use of indirect ophthalmoscopy, and serial sections of the eye aid in locating it for histologic evaluation.

Large granular lymphocyte leukemia/lymphoma in six cats.

This report describes six cases of feline large granular lymphocyte lymphoma identified by light microscopy on the basis of their characteristic azurophilic granulation in Giemsa-stained plastic sections and by electron microscopy on the basis of their typical granules. Although the granules of all the tumor cells were negative for peroxidase activity, they all demonstrated chloroacetate-esterase and acid phosphatase activity. All the tumors reacted with cross-reacting antibodies against the CD3 antigen (epsilon chain) and did not react with a cross-reacting monoclonal antibody directed against epitopes on cytoplasmic domains of the CD20 antigen. Three tumors had a positive reaction with a monoclonal human CD57-like antibody. This is highly suggestive of either a cytotoxic T cell or a natural killer cell origin of the neoplasias. In three cats, although other abdominal organs were affected to a variable extent, the main neoplastic lesions were localized in the gastrointestinal tract and the jejunal lymph nodes. In contrast, in the other three cats, organ involvement was more widespread, affecting the lung (two), myocardium (two), precardiac mediastinum (one), salivary gland (one), and spinal cord (one); in addition, leukemia was present in two of these cats. The data presented indicate that tumors made up of large granular lymphocytes occur more frequently in cats than previously assumed and that they share many characteristic features with specific subtypes of clonal disorders of large granular lymphocytes in humans.

Histopathological findings in pigs of various ages suffering from spontaneous infection with the porcine reproductive and respiratory syndrome virus (PRRSV).

A retrospective study was carried out to investigate the morphology of 29 routinely necropsied German Landrace pigs of various ages, namely five fetuses, eight neonates, five suckling piglets and 11 weaners, being either serologically PRRSV-positive or born or aborted from PRRSV positive sows. Virus antigen was immunohistochemically demonstrated in 12 out of 27 (44%) lungs tested. The distinguishing histopathological features of PRRSV-induced spontaneous disease are interstitial pneumonia accompanied by secondary inflammatory alterations that become more and more pronounced with increasing age, and vascular alterations hitherto not described in animals of these age groups. The latter consist of vasculitis of the medium-sized arteries and occasionally of the veins, mainly in the lungs but also in other organs, and of perivascular lymphoplasmacytic infiltrates of various degrees of frequency and organ distribution, but present above all in the CNS-including the meninges and in the lungs. These findings, which suggest vasculotropism on the part of the PRRSV, may facilitate the histopathological diagnosis of PRRSV infections in routinely examined material.

Demonstration of feline and canine platelet glycoproteins by immuno- and lectin histochemistry.

Canine and feline platelet cytocentrifuge preparations (CCPs), cryostat and paraffin-embedded bone marrow sections were used in this study. We evaluated whether platelets, megakaryocytes and megakaryocyte precursor cells could be labelled by monoclonal antibodies (Y2/51, CLB-thromb/1, HPL1) against human platelet membrane glycoprotein GP IIIa and the GP IIb/IIIa complex or by the following 10 biotinylated lectins: concanavalin A (Con A), Lens culinaris agglutinin (LCA), Pisum sativum agglutinin (PsA), wheat germ agglutinin (WGA), peanut agglutinin (PNA), Phaseolus vulgaris lectin (PHA-L), Ricinus communis agglutinin 120 (RCA120), Ulex europaeus agglutinin-I(UEA-1), soybean agglutinin (SBA) and Dolichos biflorus agglutinin (DBA). Monoclonal antibodies Y2/51 and HPL1 cross reacted with platelets and megakaryocytic cells from both species, whereas CLB-thromb/1 was unreactive with canine preparations. Only Y2/51 labelled megakaryocytic cells in paraffin-embedded samples. LCA, PSA, WGA and PHA-L labelled feline and canine platelets and different numbers of morphologically identifiable megakaryocytes and numerous other, mostly myeloid, cells. Immunoblots of dog and cat platelet lysates using Y2/51 visualized a single protein of 95 kDa (unreduced), a mol.wt value within the range of those reported for GP IIIa. Some of the platelet (but not necessarily megakaryocyte) glycoproteins reacting with LCA, PSA and WGA could be identified in lectin blots following one- or two (nonreduced/reduced)-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Thus in dogs and cats, the immunohistochemical detection of GP IIIa (and eventually GP IIb/IIIa) rather than lectin binding patterns could be important for the diagnosis of megakaryoblastic leukaemias.