Tumor size, leukocyte adherence inhibition and serum levels of tumor antigen in dogs with the canine transmissible venereal sarcoma

Canine transmissible venereal tumour: Cytogenetic origin, immunophenotype, and immunobiology. A review

Canine transmissible venereal tumour (CTVT) is the only known naturally occurring tumour that can be transplanted as an allograft across major histocompatibility (MHC) barriers within the same species, and even to other members of the canine family, such as foxes, coyotes and wolves. The progression of this tumour is unique in that, it follows a predictable growth pattern. In natural and experimental cases, the growth pattern includes progressive growth phase, static phase and regression phase, and this is followed by transplantation immunity in immunocompetent adults, while metastasis occurs in puppies and immunosuppressed dogs. Because of the uniqueness of CTVT transmission and progression, experimental investigations of various aspects of the biology of CTVT have been used to provide clues to the immunobiology of both animal and human tumours. This review examines the current state of knowledge of the aspects of the cytogenetic origin, immunophenotype, immunobiology and immunotherapy of CTVT.

Contrast-enhanced transrectal ultrasonography of a novel canine prostate cancer model

OBJECTIVE

This study evaluated the utility of a new animal model for prostate cancer imaging using a new ultrasonographic contrast agent (Sonazoid [NC100100]; Amersham Health, Oslo, Norway), for prostate cancer detection.

METHODS

Twenty-four dogs had a canine transmissible venereal sarcoma cell line injected (50 million cells/mL) directly into the prostate, producing a neoplasm in 15 to 40 days. Transrectal ultrasonography was performed in power Doppler mode on 8 dogs (phase I) and in gray scale phase inversion harmonic imaging mode on 16 animals (including control animals without tumors; phase II). Evaluations were repeated after intravenous injections of the contrast agent (dose, 0.00625-0.20 microL/kg). Histopathologic examination was performed after each study. For the phase II experiments, sensitivity, specificity, and accuracy were calculated.

RESULTS

The contrast agent improved visualization of the prostate cancer vascularity and delineation of tumor size and shape in both power Doppler and phase inversion harmonic imaging modes. Canine transmissible venereal sarcoma tumors ranging from 3 x 5 to 40 x 50 mm were detected. The accuracy for detecting the number of prostate tumors increased (in phase II) from 67% to 87% with the addition of the contrast agent. Histopathologic examination confirmed the ultrasonographic findings and revealed typical canine transmissible venereal sarcoma cells infiltrating the prostate with moderate neovascularity.

CONCLUSIONS

The novel canine tumor model was useful for evaluating ultrasonographic prostate imaging techniques. Improved detection of prostate tumors in dogs was possible with gray scale phase inversion harmonic imaging of the contrast agent. The accuracy of lesion detection increased from 67% to 87%.

Immunophenotype of the canine transmissible venereal tumour

The canine transmissible venereal tumour is a naturally occurring contagious round-cell neoplasia which is primarily located in the mucous membrane of the external genitalia in dogs of either sex. In order to specify the controversial cytogenetic origin of this round-cell tumour, 14 cases of canine transmissible venereal tumour, formalin- or Bouin-fixed and paraffin-embedded, were subjected to extensive immunophenotypic analysis using reagents specific to a variety of cytoplasmic or surface antigens: lysozyme, ACM1 antigen, vimentin, neuron-specific enolase, glial fibrillary acidic protein, desmin, alpha smooth muscle actin, CD3, IgG, kappa and lambda light chains, and keratin. Lysozyme immunoreactivity was detected in all cases, ACM1 antigen in 11 of 14, neuron-specific enolase in 11 of 14, vimentin in 10 of 14, glial fibrillary acidic protein in 4 of 14 and desmin in 1 of 14. All the sections were negative to keratins, alpha smooth muscle actin and CD3, whereas in five cases, perivascular tumour cells contained Ig G, kappa and lambda light chains. The immunoreactivity to lysozyme and ACM1 antigen supports the hypothesis of a histiocytic immunophenotype for the canine transmissible venereal tumour.

Detection of tumor-associated antigens in sera of canine cancer patients by monoclonal antibodies generated against canine mammary carcinoma cells

Two murine monoclonal antibodies (MAbs), 1A10 and SB2, generated against a canine mammary carcinoma cell line, were used in a competitive enzyme-linked immunosorbent assay (ELISA) to measure tumor-associated antigens (TAAs) in canine serum samples. Sera were tested from disease-free dogs and from dogs diagnosed with mammary carcinoma, non-mammary carcinoma, sarcoma, benign mammary tumor, benign non-mammary tumor, or non-neoplastic disease. Serum antigen concentrations measured by ELISA were expressed as inhibitory units (IU). The upper limit of normal, defined as the mean plus 2 SD of the TAA concentration in disease-free dogs, was 20 IU with antibody 1A10 and 22 IU with antibody SB2. Compared with disease-free dogs, the frequency of TAA-positive sera was significantly greater (P < 0.05) among dogs with mammary or non-mammary carcinoma when tested with MAbs 1A10 or SB2, and also with sarcoma when tested with MAb SB2. Testing a serum sample with both antibodies rather than just one increased the sensitivity of the competitive ELISA for TAA detection. The presence of TAA in serum might serve as a useful marker for certain types of carcinomas or sarcomas in canine cancer patients.