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Tumor antigen (TA) associated with the canine transmissible venereal sarcoma (CTVS) was detected in the sera of dogs bearing the tumor. Rabbit antisera specific for tumor antigen and 3 M KCl extracts of CTVS cells were used in both a competitive enzyme-linked immunosorbent assay (ELISA) and antigen-capture ELISA to quantify levels of circulating TA. In a study of 29 dogs bearing the transplanted CTVS, levels of circulating TA correlated positively with tumor volume. In a longitudinal study of four dogs receiving a transplant of 10(8) viable CTVS cells, circulating CTVS antigen was detected transiently 2 days after transplantation, while persistent levels of TA associated with increasing tumor volume were demonstrable 19-34 days after transplantation. In three of four tumor-bearing dogs, levels of serum TA correlated inversely with values obtained with peripheral blood leukocytes in the leukocyte adherence inhibition (LAI) assay; elevated levels of circulating TA found in dogs with large (greater than 7 cm3) tumors were associated with decreased LAI reactivity of peripheral blood leukocytes. TA could not be detected in sera 48-72 h after surgical removal of CTVS whereas LAI reactivity of peripheral blood leukocytes to CTVS antigen rebounded 1-3 weeks following tumor excision. Results of this study support the use of the competitive ELISA and LAI techniques in assessing levels of circulating tumor antigen, tumor burden and tumor-specific immunity.

The structure of canine transmissible venereal sarcoma (CTVS) has been examined from 14 to 71 days after implantation. During early growth, the tumour appears to be composed primarily of loosely arranged, round cells and a few fibroblast-like cells. As the tumour mass increases, the round cells become tightly packed with highly interdigitating plasma membranes. The number of irregularly shaped round cells and fibroblast-like cells increases with increasing tumour mass. Collagen and reticular fibres can be found in early tumours, frequently in association with the round cells, and in regions devoid of fibroblast-like cells. During tumour regression, cellular degradation is evident in fibroblast-like and irregularly shaped cells as well as round cells. The data suggest that transformation may occur in the course of tumour growth, causing morphological change from round to fibroblast-like cells, and that CTVS is an undifferentiated round-cell sarcoma capable of differentiation in a fibroblastic direction. Also present, primarily in tumour cells from newborn dogs, are cytoplasmic lamellar arrays and crystalline virus-like structures, both previously described in other forms of tumor cells. Images Figs. 1-3 Fig. 4 Figs. 5-8 Fig. 9 Figs. 10-12 Figs. 13-14

Leukocyte adherence inhibition (LAI) reactivity of various lymphoid tissues of dogs with canine transmissible venereal sarcoma (CTVS) at different stages of growth was determined by the tube LAI test. Tumors were classified at the time of excision into progressor, steady state, and regressor stages of growth. The LAI reactivity to CTVS antigen extract of spleen, draining and non-draining lymph-node cells, and peripheral blood leukocytes of regressors (non-adherence index--NAI of 172.8 +/- 46.8, 148.1 +/- 64.7, 138.7 +/- 47.3, and 172.2 +/- 60.7, respectively) was significantly greater than that of progressors (46.1 +/- 20.0, 38.5 +/- 21.5, 50.2 +/- 30.0, 24,6 +/- 37.2, respectively, p less than 0.001) and normal dogs (47.5 +/- 22.8, 54.6 +/- 24.6, 26.7 +/- 14.0, 50.9 +/- 22.4, respectively, p less than 0.001). In contrast, LAI reactivity of progressor lymphoid tissues to CTVS antigen extract did not differ significantly from that of normal dogs. LAI reactivity of lymphoid tissues from steady state tumor bearers (97.9 +/- 39.2, 80.7 +/- 47.3, 87.1 +/- 40.0, 85.1 +/- 53,9, respectively) was intermediate between and significantly different from LAI reactivities of regressor (p less than 0.05) and progressor (p less than 0.01) lymphoid tissues. Significant LAI reactivity observed in regressors suggests the presence of a functional effector cell mechanism associated with spontaneous regression of CTVS. The three distinct patterns of LAI reactivity observed in tumor-bearing dogs appear to correlate with the clinical course of tumor growth.

Sequential changes in canine transmissible venereal sarcoma (CTVS) extract-induced leukocyte adherence inhibition (LAI) reactivity of peripheral blood leukocytes (PBL) were monitored in dogs from the time of tumor inoculation through progressive growth and spontaneous regression or surgical excision of CTVS. The time-course profiles of LAI reactivity of tumor dog PBL correlated with the clinical stage of tumor growth, substantiating our previous findings in a cross-sectional study. The kinetics of the time-course appearance of LAI reactivity observed and the demonstration of a rapid anamnestic response following tumor challenge indicate further that LAI is a reliable in vitro measure of in vivo tumor immunity. A significant increase in CTVS antigen extract-induced LAI reactivity observed in the PBL during tumor regression suggests that LAI reflects a functional effector cell mechanism associated with spontaneous regression of CTVS. By contrast, absence of significant LAI reactivity of PBL during progressive tumor growth suggests the presence of serum blocking factors. In addition, a substantial rebound in LAI reactivity observed in the PBL of dogs 3 to 7 days following surgical excision of progressively growing CTVS provides further evidence that tumor-cell components are associated with progressive tumor growth and diminished LAI reactivity.

Electron microscopic study of the canine transmissible venereal sarcoma (N = 26) at different stages of growth showed that tumors in a progressive phase of growth (N = 12) were comprised mostly of large, round cells with prominent nuclei and nucleoli, a few spindle-shaped cells and collagen fibers, focal areas of necrosis, and lymphocyte infiltrates. Regressing tumors (N = 9) had the fewest viable round cells, greater numbers of infiltrating leukocytes, and were comprised almost entirely of connective tissue (collagen bundles) in the latest stages of regression. The infiltrating leukocytes consisted primarily of lymphocytes, some eosinophils, and neutrophils, but very few macrophages. Round-cell nuclei contained numerous perichromatin and interchromatin granules. Their cytoplasm often had annulate lamellae complexes and large deposits of glycogen. Loosely packed tumor cells had extensive proliferation and elongation of cytoplasmic extensions (filopodia). Evidence for cell-mediated tumor cell lysis was demonstrated by degenerative changes in tumor cells which were closely apposed to lymphocytes. Spindle-shaped cells in regressing tumors had intravacuolar collagen fragments, suggesting a possible degradative capacity by these cells. Canine transmissible venereal sarcoma, also called transmissible venereal tumor of dog and Sticker's sar- coma, is a naturally occumng round cell neoplasm of the genital tracts of male and female dogs. Although normally transmitted through coitus, tumors may be induced experimentally by inoculation of viable tumor cells into normal, non-preconditioned dogs. In either neonatal or immunosuppressed dogs, this sarcoma usu- ally grows vigorously and meta~tasizes,~.~~ but the his

We examined the regulation of leukocyte glass adherence and tube leukocyte adherence inhibition (LAI) reactivity by serum factors in dogs with regressing or progressing canine transmissible venereal sarcomas (CTVS). Both regressor and progressor peripheral blood leukocytes (PBL), draining and non-draining lymph node cells (LNC), and splenic leukocytes were significantly responsive to CTVS antigen extract in tube LAI. In contrast, a significant decrease in basal glass adherence of progressor PBL, draining and non-draining LNC, and splenic leukocytes was observed. Normal glass adherence was restored to progressor leukocytes by extensive washing with warm serum-free media, while significant tube LAI responsiveness to CTVS antigen extract was maintained. Preincubation of regressor PBL and LNC with progressor sera in two-stage tube LAI decreased the basal glass adherence of treated leukocytes. This effect of progressor sera was heat labile, a characteristic of CTVS antigen. Collectively, these findings suggest that progressor leukocytes and progressor sera treated regressor leukocytes were activated by interaction with serum CTVS antigen and thus behaved in tube LAI as stimulated cells, even in the absence of CTVS antigen. Regressor but not progressor sera were shown to contain anti-CTVS IgG with specific arming activity for normal dog PBL, but not LNC in two-stage tube LAI. The nonadherent response of peripheral blood neutrophils in two-stage tube LAI was proportional to the concentration of arming IgG, whereas no change was observed in glass adherence of PBL. The results of this study define the role of progressor and regressor serum factors in the mechanism of tube LAI and demonstrate a relationship between leukocyte glass adherence and the clinical course of CTVS. These findings show that tube LAI is a simple and reproducible measure of active factors in the immune response to a tumor.

Virus-like particles measuring approximately 110 nm in diameter were found, along with parvoviruses, in a fecal specimen of a parvovirus-infected dog. Under the electron microscope, the outer component of the particles was found to be composed of what appeared to be numerous fine spikes or a solid coat perforated by many regular small slits. The inner ‘core’ of the particle had an irregular border, measured approximately 60 nm in diameter and was occasionally eccentrically located.

Intraarticular inoculation of Mycoplasma bovis into the joints of six-week-old calves caused severe arthritis in five inoculates and mild arthritis in a sixth. Intraarticular inoculation of killed M. bovis did not cause arthritis.Arthritic calves had fever, joint swelling, lameness, neutrophilia, and intercurrent pneumonia from which M. bovis could not be recovered.Gross lesions were massive fibrinosuppurative synovitis and tenosynovitis, erosion of cartilage, and its replacement by polypoid granulation tissue. Histologic lesions were extensive ulceration of synovial membranes, leukocytic infiltration of the suhsynovium, congestion, hyperemia, and thrombosis of the subsynovial vessels. Cartilage erosion was accompanied by chronic osteomyelitis and formation of pannus tissue.The presence of thrombi and platelet aggregates suggests that the inflammatory process in the synovium may arise from the interaction of M. bovis with the vasculature and the coagulation process of the host.

Canine transmissible venereal sarcoma (CTVS) is a contagious neoplasm which regresses spontaneously in adult dogs but metastasizes and kills puppies transplanted with the neoplasm at a very young age. Immunofluorescence studies showed that 30 +/- 14% of cells from steady-state and 22 +/- 7% of cells from regressing tumors had membrane-bound antibodies which could be eluted out with warm washes at 24 degrees C, whereas the cells from progressor tumors had very little such antibody (6 +/- 6%). Time-course kinetics of anti-CTVS antibodies in the serum of tumor-bearing dogs did not correlate well with tumor volume, however, the presence of such antibodies in adult dogs (47 +/- 13%) but absence (0%) in the puppies with tumor metastasis suggested the importance of antibodies in resistance to metastasis.

The levels of T-lymphocyte subpopulations expressing IgMFc and IgGFc receptors (i.e., T mu lymphocytes and T gamma lymphocytes, respectively) were quantitated for T-lymphocytes obtained from peripheral blood, draining and nondraining lymph nodes, and the tumor mass during progressive growth and spontaneous regression of the canine transmissible venereal sarcoma. Analysis of the T-lymphocyte subpopulations in these lymphoid compartments demonstrated that distinct profiles of T mu and T gamma lymphocytes correlated respectively with the growth and regression statuses of the tumor. The percent of T gamma lymphocytes in the peripheral blood of dogs with progressing, steady-state, and late-regressing tumors was significantly increased over that of control dogs (P less than .05, P less than .001, and P less than .001, respectively) and over that of dogs with early-regressing tumors (P less than .05, P less than .01, and P less than .02, respectively). The percent of T gamma lymphocytes in the lymph nodes draining the tumor was observed to have a significant increase in dogs with progressing (P less than .01), steady-state (P less than .01), and late-regressing (P less than .001) tumors compared with that in control dogs. The percentage of T gamma lymphocytes was observed to have a significant increase in the nondraining lymph nodes of dogs with steady-state and late-regressing tumors compared with that of control dogs (P less than .01 and P less than .002, respectively) and that of dogs with progressing tumors (P less than .001 and P less than .0005, respectively). The percent of tumor-infiltrating T gamma lymphocytes was lowest in tumors that were growing progressively. A significant increase in T gamma lymphocytes was observed in steady-state (P less than .05), early-regressing (P less than .001), and late-regressing (P less than .05) tumors. Early-regressing tumors contained significantly (P less than .005) greater levels of T gamma lymphocytes than did late-regressing tumors.

Immunoferritin and immunoperoxidase reagents were used to localize a tumor-associated antigen (TAA) of the canine transmissible venereal sarcoma (CTVS). Round tumor cells from the CTVS at different stages of growth, i.e., progressive, steady state, and regressing, had TAA diffusely distributed throughout the cytoplasm. In general, TAA was not found on the plasma membrane, within the nucleus, between inner and outer membranes, in cytoplasmic vacuoles, or specifically with any part of the cytocavitary system. Transitional tumor cells, which are intermediate cell types between round cells and spindle-shaped cells and which appear in the tumors at steady state and regressing stages, contained less TAA in their cytoplasm than did the round cell type. The microvilli of tumor cells also contained TAA, suggesting that, in addition to whole cell lysis, shedding of all or parts of these processes may be a mechanism of TAA release as evidenced by the presence of antigenic activity in the extracellular material.