Increased IL-6 gene expression and production in patients with common variable immunodeficiency.

We have studied IL-6 gene expression and production by in vitro stimulated peripheral blood mononuclear cells (PBMC) isolated from common variable immunodeficiency (CVI) patients. A strong hybridization signal for the IL-6 probe was observed in mRNA extracted from phytohaemagglutinin (PHA)- and PHA/phorbol myristate acetate (PMA)-stimulated PBMC from most of 12 CVI patients analysed. IL-6 production by PHA-stimulated PBMC from 28 CVI patients was evaluated in ELISA and found to be significantly (P < 0.0001) higher than in normal controls. IL-6 production, however, did not correlate with the lymphocyte populations examined, nor with the absolute number of monocytes. We have also showed that IL-6 was able to increase IgM secretion by several Epstein-Barr virus (EBV)-transformed cell lines derived from both normal donors and CVI patients, but it failed to modify substantially the amounts of IgM and IgG produced in vitro by PBMC derived from CVI patients and activated with pokeweed mitogen (PWM) or anti-IgM. Our data indicate that IL-6 gene expression and production is increased in CVI, but CVI cells do not respond to IL-6 with increased production of immunoglobulin.

Fibroblast-derived factors preserve viability in vitro of mononuclear cells isolated from subjects with HIV-1 infection.

OBJECTIVE: Peripheral blood mononuclear cells (PBMC) from HIV-infected subjects have an increased mortality rate (MR) when incubated in vitro for 3 days in a culture medium. We have previously shown that fibroblast-conditioned medium (FCM) can preserve viability, without significant activation, of human lymphocytes in vitro. We therefore tested the ability of two FCM and other factors to reduce spontaneous MR in HIV-positive PBMC. METHODS: PBMC were cultured for 3 days in control medium and medium supplemented with FCM or recombinant cytokines [interleukin (IL)-2, IL-6, IL-7, granulocyte macrophage colony-stimulating factor]. Cells viable at day 3 were counted in a cytofluorimeter after staining with ethidium bromide. DNA was extracted from the cultures and evaluated for the presence of low molecular weight fragmentation. RESULTS: The MR of PBMC from 51 HIV-positive subjects and from 21 healthy controls were 30.1 and 9.5%, respectively (P < 0.0001). The MR was higher in 40 patients with a CD4+ lymphocyte count < 400 x 10(6)/l than in subjects with a count > 400 x 10(6)/l (32.84 versus 20.96%; P = 0.047). IL-2 and FCM significantly reduced MR in HIV-positive subjects (MR: 17.8 and 20.4%; P: < 0.001 and 0.005, respectively). This effect was more evident in subjects with a CD4+ lymphocyte count < 400 x 10(6)/l and in subjects with negative p24 antigenaemia. Cellular proliferation accounts for increased survival in IL-2-supplemented cultures but not in those with FCM. DNA was extracted from fresh PBMC and cells cultured for 3 days for 22 HIV-positive cases. DNA degradation was documented and bands related to an apoptotic mechanism of death observed, especially in subjects with more advanced disease. CONCLUSIONS: Our data suggest that FCM inhibits accelerated cell death in vitro of PBMC isolated from HIV-positive patients.