Nuclear factor-kappaB activation in human monocytes stimulated with lipopolysaccharide is inhibited by fibroblast conditioned medium and exogenous PGE2.

The nuclear factor kappaB (NF-kappaB) is thought to be crucially involved in the gene activation of several cytokines, including tumor necrosis factor alpha (TNF). Previously, we showed that fibroblast conditioned medium (FCM) is able to inhibit both TNF mRNA accumulation and protein release in peripheral blood-derived human monocytes (PBM) stimulated with lipopolysaccharide (LPS). In this study we have investigated the effect of FCM on the LPS-induced DNA-binding activity of NF-kappaB, by means of electrophoretic shift assay (EMSA). We provide evidence that FCM strongly inhibits the LPS-induced NF-kappaB activation in PBM. Furthermore, we show that exogenous PGE2 mimics the NF-kappaB inhibitory effect of FCM. On the other hand, FCM produced in the presence of indomethacin does not inhibit NF-kappaB activation by LPS. Our results lend further support to the hypothesis that inflammatory and immune responses of monocytes/macrophages may be modulated at the molecular level by signals originating from tissue structural cells such as fibroblasts.

Immunological reactivity of peripheral lymphocytes in kidney transplant patients.

The in vitro lymphocyte response to mitogens (PHA, PWM) and specific antigens (PPD, LPS, histocompatibility antigens), as well as their capacity to form spontaneous SRBC rosettes, was evaluated in 24 renal transplant patients; of these, 13 were studied both before and after kidney graft. The results of our tests, compared to the range of values obtained from healthy controls, show that continuous immunosuppressive therapy does not significantly depress the in vitro mitotic potentiality of lymphocytes in spite of greatly reduced levels of circulating T cells. The in vitro escape of lymphocytes from the action of immunosuppressive drugs frustrated the aim of calibrating the immunodepressive therapy for each patient. A better understanding of the immunosuppression in an individual will perhaps be obtained from a more prolonged observation of the in vitro lymphocyte reactivity in a larger number of patients.

Monitoring and modulation of recipient immune responsiveness to prevent kidney graft rejection in the early post-transplant period.

In 41 consecutive living and cadaver donor renal transplant recipients, immunological monitoring was performed 2--3 times a week for the first two post-transplant months. Monitoring consisted of: 1) Circulating T and B cell levels (E-EAC Rosette assay) 2) T cell reactivity (PHA-Con A) 3) LMC and ADCC reactivity Rejection was diagnosed by standard techniques including radioisotope renal scans and biopsy in some cases. Immunosuppression consisted of prednisone, imuran, cyclophosphamide and horse ALG. In 32 rejection episodes in the first two months, 22 (68%) were associated with a rise in T cell levels. Rejection activity also correlated with an augmented PHA mitogenesis count of 20 +/- 5%. There was no positive correlation between Con A mitogenesis and rejection. There was also no correlation between rejection and circulating B cell levels. There was no significant correlation between a positive ADCC and graft rejection. Futhermore a positive ADCC in association with a negative LMC resulted in excellent long-term graft function. In conclusion, an excellent correlation of levels of circulating T cells and T cell reactivity with early in vivo rejection was shown.