TAL-1 protein expression in vascular lesions.

The distribution of TAL-1 protein, an important vascular promoter in mice, has been examined immunohistochemically in a range of human vascular lesions and normal tissues. Formalin-fixed, paraffin-embedded vascular lesions including granulation tissue, haemangiomas, Kaposi's sarcomas, spindle cell haemangioendotheliomas, and angiosarcomas, were examined using a monoclonal antibody to recombinant TAL-1. Endothelial cells in all lesions gave positive immunostaining of variable intensity. Granulation tissue and spindle cell areas of the vascular tumours gave the strongest staining (nuclear and cytoplasmic). The better-differentiated endothelial cells within the tumours and resident well-formed vessels were less positive and some cells were in fact negative. The malignant endothelial cells in angiosarcomas showed less intense positive staining than KS cells. This study has shown TAL-1 protein expression in a range of reactive, benign, and malignant vascular lesions. Protein expression appears to be stronger in the spindle cell areas, perhaps reflecting greater expression in less-differentiated endothelial cells.

Detection of Maedi-Visna virus antibodies using a single fusion transmembrane-core p25 recombinant protein ELISA and a modified receiver-operating characteristic analysis to determine cut-off values.

The core p25 and transmembrane (TM) genes of Maedi-Visna virus (MVV) were cloned individually into the pGEX-2T expression vector. Both proteins were expressed as a combined fusion protein in frame with glutathione S-transferase (GST). The purified recombinant antigens (GST-TM and GST-TM-p25) were used to develop a MVV ELISA. A preliminary assessment of the diagnostic potential of the recombinant antigens (GST-TM and GST-TM-p25) was made by testing the antigens against 46 seropositive and 46 seronegative sheep and comparing the results with a commercial p25 ELISA kit. A two-graph receiver operating characteristic (TG-ROC) analysis program was used to interpret the data. The GST-TM-p25 ELISA was more sensitive than the commercial assay which is based on the p25 antigen alone and more specific than the GST-TM ELISA.

Detection of antibodies to Newcastle disease virus in ostriches (Struthio camelus) by an indirect ELISA.

A two-graph receiver operating characteristic analysis, performed on the hemagglutination-inhibition (HI) and enzyme-linked immunosorbent assay (ELISA) test results of a Newcastle disease virus (NDV)-positive and NDV-negative control group of ostrich sera, proved that the ELISA was superior to the HI in both sensitivity and specificity. Comparison of results of the two assays performed on a panel of simulated positive sera ranging from very weak to very strong showed that the ELISA was at least 10 times more sensitive than the HI in detecting low levels of ostrich antibodies to NDV. The ELISA also has the advantage of using untreated serum in a single dilution as opposed to the HI test, which uses pretreated serum in titration.

HIV infection and neoplasia.

HIV infection predisposes to several neoplastic conditions, especially non-Hodgkin lymphoma (NHL) and Kaposi's sarcoma (KS), and also intraepithelial cervical neoplasia (CIN) and anal neoplasia (AIN) (but not cervical or anal invasive cancer) and possibly seminoma. For neoplasias associated with oncogenic human viruses (ie, some NHL, CIN, AIN, and probably KS) the role of HIV is most probably linked to its immunosuppressive effect and interference with immune-mediated tumour surveillance. HIV-1, through its regulatory protein tat, might also have a direct promoting effect on KS lesions but it is not essential for their development. The increased frequency of Burkitt's lymphoma and Epstein-Barr-virus-negative large-cell lymphoma in AIDS patients, but not in immunosuppressed transplant patients, and the increased rate of testicular tumours in HIV-infected individuals remain unexplained and may indicate either a direct role for HIV or other cofactors.

Thymidine phosphorylase expression in Kaposi sarcoma.

AIMS: To examine the immunohistochemical distribution of thymidine phosphorylase (TP) in all clinicopathological subtypes of Kaposi sarcoma. METHODS: Thirty two biopsy specimens of Kaposi sarcoma (29 patients) were studied. Six of these patients represented classic, six endemic, eight HIV associated, seven post-immunosuppression/transplant related, and two unclassified variants of Kaposi sarcoma. The average age was 49 years (range 22-83 years) and the male: female ratio 24:5. Four samples of angiosarcoma and one of spindle cell haemangio-endothelioma were stained in parallel. All specimens were fixed in formalin, embedded in paraffin wax and processed routinely. Immunohistochemistry was carried out using an antibody directed against CD31 (JC70) and the monoclonal antibody P-GF.44C against TP. RESULTS: All biopsy specimens showed immunoexpression for TP. The spindle cell component stained more strongly than newly formed endothelium lined vessels and normal, resident vessels at a distance from the lesions. CONCLUSIONS: The strong immunoexpression of TP suggests up-regulation of TP and a role for TP in angiogensis in Kaposi sarcoma. The mechanism for the up-regulation of TP remains unknown, but viral infections may trigger it. The differential staining of the various cell components of Kaposi sarcoma also suggest that TP either plays a role in the differentiation and maturation of Kaposi sarcoma or is a reflection of such changes.

Spontaneous hybridoma formation induced by immunization with Haemophilus paragallinarum: evidence for a lipopolysaccharide fusion inducer.

The phenomenon of spontaneous fusion between myeloma cells and splenocytes from mice immunized with formalin-inactivated Haemophilus paragallinarum cells, has been reported on recently (1). The identity and properties of the bacterial inducer of fusogenicity of splenocytes have been further investigated with the aid of a monoclonal antibody VF3 against H. paragallinarum (2), which has a bacterial strain specificity correlating with the ability of the strains to induce spontaneous fusion between splenocytes of immunized mice and myeloma cells. It was shown that the lipopolysaccharide fraction of the bacteria was required for the induction of fusogenicity. LPS involvement was clearly indicated by the parallel effects on VF3 antigenicity and fusogenic inductivity of various treatments such as proteolytic digestion, periodate oxidation and sensitivity towards alkali, acid or freezing.

Spontaneous fusion between splenocytes and myeloma cells induced by bacterial immunization.

Spontaneous fusion between lymphoid and carcinoma cells in vivo has been described previously. Splenocytes from mice treated with LPS or mitogen have been reported to fuse better with myeloma cells using PEG as fusion agent than splenocytes from untreated mice. We report a phenomenon where immunization of mice with formalin treated, whole Haemophilus paragallinarum bacteria induced spontaneous fusion of splenocytes with myeloma cells in vitro, without the aid of any fusion agent. Co-immunization of mice with H. paragallinarum and an unrelated antigen (hen's egg white lysozyme), followed by co-culturing of the immune splenocytes with SP2/0 myeloma cells, yielded stable hybridoma cell lines producing anti-lysozyme antibodies. H. paragallinarum may be used in adjuvants to simplify the production of monoclonal antibodies, and the discovery of a promotional activity of a gram negative bacterium on cell fusion and hybridoma formation may shed new light on spontaneous fusion as a natural immune phenomenon in cancer.