New data on the cytolytic effects of natural killer cells (Kurloff cells) on a leukemic cell line (guinea pig L2C)

Hematological Assessment in Pet Guinea Pigs (Cavia porcellus): Blood Sample Collection and Blood Cell Identification

Pet guinea pigs are presented to veterinary clinics for routine care and treatment of clinical diseases. In addition to obtaining clinical history and exam findings, diagnostic testing may be required, including hematological assessments. This article describes common blood collection methods, including venipuncture sites, the volume of blood that can be safely collected, and handling of the blood. Hematological parameters for normal guinea pigs are provided for comparison with in-house or commercial test results. A description of the morphology of guinea pig leukocytes is provided to assist in performing a differential count.

Hematological assessment in pet guinea pigs (Cavia porcellus): blood sample collection and blood cell identification

Pet guinea pigs are presented to veterinary clinics for routine care and treatment of clinical diseases. In addition to obtaining clinical history and exam findings, diagnostic testing may be required, including hematological assessments. This article describes common blood collection methods, including venipuncture sites, the volume of blood that can be safely collected, and handling of the blood. Hematological parameters for normal guinea pigs are provided for comparison with in-house or commercial test results. A description of the morphology of guinea pig leukocytes is provided to assist in performing a differential count.

Nontraditional Applications in Clinical Pathology

Most published reviews of preclinical toxicological clinical pathology focus on the fundamental aspects of hematology, clinical chemistry, coagulation, and urinalysis in routine toxicology animal species, for example, rats, mice, dogs, and nonhuman primates. The objective of this continuing education course was to present and discuss contemporary examples of nonroutine applications of clinical pathology endpoints used in the drug development setting. Area experts discussed bone turnover markers of laboratory animal species, clinical pathology of pregnant and growing laboratory animals, clinical pathology of nonroutine laboratory animal species, and unique applications of the Siemens Advia® hematology analyzer. This article is a summary based on a presentation given at the 31st Annual Symposium of the Society of Toxicologic Pathology, during the Continuing Education Course titled “Nontraditional Applications of Clinical Pathology in Drug Discovery and Preclinical Toxicology.”

Lung macrophages from bacille Calmette-Guérin-vaccinated guinea pigs suppress T cell proliferation but restrict intracellular growth of M. tuberculosis after recombinant guinea pig interferon-gamma activation

The guinea pig model of low-dose pulmonary tuberculosis has been used to study the pathogenesis of infection as well as the mechanisms of bacille Calmette-Guérin (BCG) vaccine-induced resistance. We investigated the function of lung cells from naive and BCG-vaccinated guinea pigs after enzymatic digestion of lung tissue with collagenase and DNase I. The total lung digest cells proliferated poorly to purified protein derivative (PPD) but comparatively better to ConA as assessed by [(3)H]-thymidine uptake. However, the non-adherent population obtained after plastic adherence of lung digests showed an enhanced response to concanavalin A (ConA) and PPD. Therefore, proliferation to ConA and PPD of nylon wool-purified T cells co-cultured with peritoneal (PMøs), alveolar (AMøs) or lung macrophages (LMøs) was assessed. Co-cultures of lung T cells and PMøs showed maximum proliferation to PPD, whereas proliferation was suppressed significantly by the addition of AMøs or LMøs. The response of T cells to ConA was unaffected in co-cultures. Incubation of co-cultures with recombinant guinea pig interferon-gamma (rgpIFN-gamma) did not reverse the suppression. In contrast, rgpIFN-gamma-treated plastic adherent LMøs that were non-specific esterase-positive were capable of reducing the intracellular growth of Mycobacterium tuberculosis. Similarly, total, non-adherent and adherent lung digest cells from BCG-vaccinated guinea pigs showed IFN-gamma and tumour necrosis factor (TNF)-alpha mRNA expression in response to ConA, lipopolysaccharide or PPD by reverse transcription-polymerase chain reaction followed by release of TNF protein but not IFN. These studies indicate that rgp-IFN-gamma-treated lung tissue macrophages from BCG-vaccinated guinea pigs are defective for inducing antigen-specific proliferation in T cells, but control the intracellular accumulation of virulent M. tuberculosis.

Novel two-parameter flow cytometry (MIL4/SSC followed by MIL4/CT7) allows for identification of five fractions of guinea pig leukocytes in peripheral blood and lymphoid organs

Though the guinea pig has been an extremely useful animal model for a variety of diseases, the tools necessary to undertake a full-scale immunological analysis of the guinea pig have been lacking. For instance, traditional two-parameter forward/side scatter (FSC/SSC) flow cytometry, though effective in human and other animal models, is unable to adequately identify the distinct fractions of guinea pig peripheral blood leukocytes (PBL). We introduce here a new flow cytometric technique (MIL4/SSC followed by MIL4/CT7) which redresses this lack by identifying and characterizing five distinct fractions of PBL: neutrophils, lymphocytes, monocytes, eosinophils plus basophils, and the novel MIL4(-)SSC(large)CT7(high) population. The MIL4(-)SSC(large)CT7(high) cells possess cytoplasmic inclusion bodies of variable size that were positive for periodic acid Schiff (PAS). Their cell surface stained positive for the helper/inducer lymphocyte markers, T cell markers, CD45, Thy-1, asialo GM1 and FcR, but negative for B cell markers, such as membrane-type IgM, CD8 and MHC class II. The novel flow cytometric technique also allowed us to establish that the five leukocyte fractions were found in PBL, splenocytes, thymocytes and lymph node cells. Cells which were positive for inclusion bodies comprised 16.6% of splenocytes, 9.9% of PBL and 4.3% of liver cells, but were comparatively rare in lymph node cells, thymocytes, and BM cells. The novel flow cytometric technique introduced here will allow a better understanding of the response of each type of guinea pig leukocyte and thereby shed light on the diseases with which they are associated.

A first step in visual identification of different cell populations by a modified alkaline comet assay

Using a particular model of apoptosis, we here demonstrate the ability of the comet assay to differentiate between different cell populations. In our study, the natural killer Kurloff cells, used as effector cells, recognize and bind to the tumoral L2C target cells. Formation of such conjugates leads to the death of the target cells by apoptosis, as previously described by different conventional techniques. With the alkaline comet assay, a conjugate could directly be visualized as an association of an undamaged cell joined to a highly damaged cell. The modified comet assay used in this study comprises specific labelling of Kurloff cells with immunomagnetic beads, which are visible as grey-dull spheres against the bright-red staining of nuclear origin on the comet preparation. The use of such labelled effector cells suggest the potential of the comet assay to visually identify different cell populations in an unique test.

Interface accumulation of receptor/ligand couples in lymphocyte activation: methods, mechanisms, and significance

Cellular interaction is vital to the activation of most lymphocytes. At the interface between the lymphocyte and the cell that activates it, multiple receptor/ligand pairs accumulate in distinct patterns. This accumulation is intriguing, as it is likely to shape the quality of receptor signaling and thereby lymphocyte behavior. Here we address such receptor/ligand accumulation with an emphasis on T and natural killer (NK) cells. First, we discuss the strengths and limitations of commonly used approaches to visualize receptor/ligand accumulation. Second, we discuss two principal mechanisms of receptor and ligand translocation, diffusion and cytoskeletal transport, as understanding these mechanisms can be invaluable in the determination of the significance of receptor/ligand accumulation. We show that the extent of receptor/ligand accumulation at the T cell/antigen presenting cell interface is dominated by diffusion for all but the lowest affinity interactions, while patterning of these receptors/ligands within the interface is strongly influenced by cytoskeletal transport. Third, we discuss two specific issues in lymphocyte receptor/ligand accumulation. We review the abundant but frequently controversial data on T cell receptor (TCR)/major histocompatibility complex (MHC) accumulation and suggest that central TCR/MHC accumulation is a mediator of efficient T cell activation. In the investigation of NK cell/target cell interactions, we characterize the often tentative NK cell/target cell couple maintenance, as it creates a major obstacle in studying receptor/ligand accumulation.