Detection of high nerve growth factor serum levels in AIDS-related and -unrelated Kaposi's sarcoma patients.

OBJECTIVE: Nerve growth factor (NGF) is an autocrine survival factor for memory B lymphocytes. As functional B-cell deregulation is present during HIV infection, NGF serum levels were measured in HIV-infected patients and compared with the patients' clinical features. DESIGN: Sera from 48 consecutive HIV-infected patients and matched healthy controls were retrospectively and blindly analysed. Sera from seven patients with classical Kaposi's sarcoma (KS) were subsequently included in the study. The effects of NGF on spindle-shaped cells from KS lesions (KS cells) were also investigated. METHODS: NGF titration was performed by enzyme-linked immunosorbent assay (ELISA) and human herpesvirus 8 (HHV-8) antibody testing by immunofluorescent assay (IFA). NGF receptors were assessed by Western blot analysis. Cell growth assays were performed by cell counting. RESULTS: Very high median NGF serum levels were detected in all seven patients with AIDS-related KS (2500 pg/ml) compared with HIV-infected patients without KS (40 pg/ml), as well as in all seven classical KS patients (550 pg/ml) compared with healthy controls (20 pg/ml). In HIV-infected patients, NGF serum levels were significantly related to KS (P=0.0038) by stepwise multiple regression analysis, and HHV-8 seropositivity was significantly associated with KS (P=0.045) and to NGF levels (P=0.001) by logistic regression analysis. KS cells did not produce NGF but expressed both NGF receptors and presented increased proliferation rate after exogenous NGF addition. CONCLUSIONS: These results strongly suggest that increased NGF levels, possibly related to HHV-8 infection, may be involved in KS progression.

High doses of thymosin alpha 1 enhance the anti-tumor efficacy of combination chemo-immunotherapy for murine B16 melanoma.

BACKGROUND: We have reported previously that combined chemo-immunotherapy with cyclophosphamide (CY), thymosin alpha 1 (T alpha 1) and low dose interferon alpha,beta (IFN alpha beta) has significant anti-tumour effects. Here, using mouse B16 melanoma as a model, we tested whether increasing the dose of T alpha 1 could increase the anti-tumour activity of triple combination chemo-immunotherapy. MATERIALS AND METHODS: C57BL/6 mice were challenged subcutaneously with B16 melanoma cells and injected intraperitoneally with saline, CY (200 mg/kg, day 7), or CY with T alpha 1 (200, 600 or 6000 micrograms/kg/day, days 10-13) and IFN alpha beta (30,000 I.U., day 13). RESULTS: Chemo-immunotherapy with high dose (HD)-T alpha 1 caused complete tumour regression for 27.5 days after tumour cell injection (3.9 times longer than untreated controls) and delayed tumour relapse compared to all other groups. Moreover, it significantly increased the median survival time of treated mice, and cured an average of 23% of animals, while none was cured in any other group. Splenocytes from HD-T alpha 1-treated mice showed markedly increased cytotoxic activities against both YAC-l and autologous B16 tumour cells. HD-T alpha 1 treatment reversed the tumour-induced reduction in percentages of CD3 and CD4-positive splenocytes to non-tumour levels, and it increased percentages of CD8, B220 and IL-2R beta-positive cells to well beyond non-tumour controls. CONCLUSIONS: High doses of T alpha 1 improve anti-tumour efficacy of tnple chemo-immunotherapy against B16 melanoma. These effects appear to be mediated by stimulation of the host immune response.

Autocrine nerve growth factor is essential for cell survival and viral maturation in HHV-8-infected primary effusion lymphoma cells.

High levels of nerve growth factor (NGF) are found in sera from individuals infected with human herpesvirus 8 (HHV-8). BC-1 and BCBL-1 cells are primary effusion lymphoma-derived B-cell lines; BC-1 cells are infected by HHV-8 and the Epstein-Barr virus (EBV), and BCBL-1 cells are infected only by HHV-8. Both cells express NGF receptors and produce NGF, whereas RAMOS cells (a B-cell line that is negative for HHV-8 and EBV) express NGF receptors but do not produce detectable NGF. Neutralization of endogenous NGF results in cell growth inhibition and apoptosis in BCBL-1 cells and, to a minor extent, in BC-1 cells. When the HHV-8 lytic cycle is induced in BCBL-1 cells by tetradecanoyl phorbol acetate (TPA), an initial reduction of endogenous NGF production is observed, and many cells undergo apoptosis. However, at 48 hours, TPA-treated cells produce significantly more NGF than untreated controls, and a subsequent recovery of cell viability is observed. Consistent with this finding, the addition of exogenous NGF or anti-NGF antibodies to TPA-treated cells reduces or increases, respectively, the rate of apoptosis in response to TPA. Finally, electron microscopy of TPA-treated BCBL-1 cells shows that the addition of exogenous NGF increases the number of cells producing and releasing complete virions as compared with the controls (25% versus 5%). On the contrary, NGF neutralization leads to the production of defective viral progeny in about 2% of cells. These data indicate that NGF is essential for both cell survival and virus maturation in HHV-8-infected cell lines. (Blood. 2000;95:2905-2912)