Lisya Gerez

Prediction of response to treatment in superficial bladder carcinoma through pattern of interleukin-2 gene expression.

PURPOSE Superficial bladder carcinoma, treated by resection and intravesical administration of bacillus Calmette-Guérin (BCG), yields a remission rate that approaches 70%. We examined whether expression of interleukin-2 (IL-2) or interferon-gamma (IFN-gamma) genes can serve to predict response. PATIENTS AND METHODS During BCG treatment, we analyzed induction of IL-2 and IFN-gamma mRNA in peripheral-blood mononuclear cells (PBMC) from 73 patients: 51 with papillary tumors and 22 with carcinoma-in-situ (CIS). Results were correlated with remission, relapse, or tumor persistence over a 4-year follow-up period. RESULTS Independent of tumor type, induction of IL-2 mRNA was observed for patients who responded with remission, but not for those who relapsed (P = .0001). Multivariate logistic analysis showed that inducibility of IL-2 mRNA is the discriminating parameter, which yields a predictive value of 97% for remission. Of 23 patients with relapse/persistence, 22 lacked inducibility of IL-2 mRNA (sensitivity, 95.6%), while 35 of 50 patients in remission exhibited inducibility (specificity, 70%). For patients with carcinoma-in-situ, in which remission or failure depends solely on response to BCG, sensitivity and specificity were 88% and 86%, respectively; for patients with papillary tumors, they were 100% and 64%. IFN-gamma mRNA, by contrast, was clearly inducible in PBMC from all patients (P = .51). The disease-free interval increased progressively with inducibility of IL-2 mRNA; this trend was highly significant (P = .0001). CONCLUSION IL-2 gene expression is essential for mounting an antitumor response in superficial bladder carcinoma. Inducibility of IL-2 mRNA is an independent prognostic parameter and useful predictive indicator of remission versus relapse.

Hyperinducible expression of the interferon-gamma (IFN-γ) gene and its suppression in systemic lupus erythematosus (SLE)

Transient expression of IFN‐γ and IL‐2 mRNA and its control by post‐transcriptional and suppressive mechanisms were analysed in phytohaemagglutinin‐induced peripheral blood mononuclear cells (PBMC) from 47 patients with SLE and 31 age‐matched normal donors, using quantitative hybridization with antisense RNA probes. In SLE, basal levels of gene expression did not deviate from those of normal donors, but strongly aberrant patterns were obtained upon induction. The ratio of subjects exhibiting highly inducible IFN‐γ gene expression in their PBMC to those showing moderate or low inducibility was increased five‐fold in SLE (P = 0.003). High inducibility was observed for 43% of SLE patients and was equally pronounced in partial remission, mild or active disease. Inducibility of IL‐2 mRNA, by contrast, remained similar to that for normal donors. However, regulation of IFN‐γ gene expression differed for mild SLE. Patients with mild disease showing high inducibility of IFN‐γ mRNA in their PBMC not only had the highest frequency of responders, but also the highest extent of an individual response, defined by superinduction of mRNA, to agents that relieve suppression (γ‐irradiation) or post‐transcriptional down‐regulation (cycloheximide). By contrast, patients with active SLE showing high IFN‐γ mRNA inducibility had normal suppressive capacity as well as post‐transcriptional control. Hence, both high inducibility of the IFN‐γ gene and its suppression are relevant to disease. Hyperactivation of the IFN‐γ gene may be alleviated in mild SLE by a vigorous, concomitant activation of post‐transcriptional control and of cell‐mediated suppression.

Aberrant regulation of interleukin-2 but not of interferon-γ gene expression in Down syndrome (trisomy 21)

The regulated expression of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) genes was analyzed in peripheral blood mononuclear cells derived from 29 noninstitutionalized Down syndrome individuals and compared to that of 32 normal donors. Culture conditions were chosen that measure the transient, phytohemagglutinin-induced expression of IL-2 and IFN-gamma mRNA, as well as the intactness of post-transcriptional and suppressor T cell-dependent mechanisms that control this expression. The latter was achieved by analyzing, respectively, the superinduction of IL-2 and IFN-gamma mRNA occurring upon culture with cycloheximide or after low-dose gamma-irradiation. A convenient, sensitive, and quantitative assay for specific mRNA was devised, suitable for measuring mRNA levels expressed in cells from 1 ml of peripheral blood. Analysis of individuals with Down syndrome revealed a pronounced decrease in inducibility of the IL-2 gene. By contrast, induction of IFN-gamma mRNA was as vigorous as that observed for normal donors. In cells from trisomic subjects, superinduction of IFN-gamma mRNA by cycloheximide was at least as extensive as for normal donors, while in the case of IL-2 mRNA, it was weaker. These abnormal patterns of IL-2 gene expression were seen irrespective of age. Our findings demonstrate a selective impairment of IL-2 gene expression in Down syndrome, rather than a general deficiency in helper T cells.

Transient expression of human interleukin-2 and interferon-γ genes is regulated by interaction between distinct cell subsets

The level of transient expression of human IL-2 and IFN-gamma genes, we show, is regulated by dynamic interaction between two functionally distinct cell populations. One is able to express these genes, while the other, bearing one of several specific surface markers, actively inhibits their expression. Defined cell subsets were isolated from PBMC and tonsil cells using immunomagnetic beads coated with monoclonal antibodies directed against surface markers. Depletion of CD8, CD11a (Leu15), or Leu8 subsets led to a pronounced superinduction of IL-2 and IFN-gamma gene expression when the remaining cell population was stimulated with mitogen (PHA) or antigen (SEB). Thus, a 10-fold increase in production of IFN-gamma was observed after removal of CD11a (Leu15) cells constituting only a small percentage of the total cell population. By contrast, depletion of cells expressing CD19, a B cell marker, did not yield any superinduction. Conversely, CD8, CD11a (Leu15), or Leu8 cell subsets, but not CD19 cells, each inhibited the induction of IL-2 and IFN-gamma gene expression almost completely in depleted or total cell populations from which they were derived. Gene expression occurring within one cell subset could be effectively inhibited by cells from a second subset. Introduction of inhibitory cells (Leu8) into a population that actively expressed IL-2 and IFN-gamma mRNA resulted in an immediate cessation of gene expression. This suppression involves a soluble mediator, since the culture medium in which such cells were activated exerted a similarly effective inhibition.

Regulation of human interleukin-2 and interferon-gamma gene expression by suppressor T lymphocytes

Concomitant with induction of inlerleukin‐2 (IL‐2) and interferon‐gamma (IFN‐γ) gene expression in human tonsil cells, milogenic stimulation induces a transient activation of cells able to effectively suppress expression of these genes. Induction of IL‐2 and IFN‐y genes largely precedes appearance of suppressor cell activity, allowing expression of both genes to occur before strong down‐regulation is exerted by activated suppressor cells. Suppressive activity induced in one cell population can inhibit IL‐2 and IFN‐γ gene expression in another population from the same donor. The distinct nature of suppressor cells is supported by the absence of down‐regulation of IL‐2 gene expression in a helper cell line. M LA‐144: yet, in these cells, negative control can be expressed when active suppressor cells are introduced. Our findings support the concept that actual levels of IL‐2 and IFN‐γ gene activity are regulated to a large extent by the differential kinetics of activation of suppressor cells on one hand and of cells expressing the IL‐2 and IFN‐γ genes on the other.

The potential to express or suppress human interleukin-2 and interferon-γ genes is not restricted to distinct cell subsets

Cell surface markers CD4, CD8, Leu8 and Leu15 (CD11) were used to separate human lymphoid cell subsets with monoclonal antibody-coated immunomagnetic beads. We show that each of these subsets is able to suppress the induction of IL-2 and IFN-gamma genes effectively. This is manifested by a pronounced superinduction of IL-2 and IFN-gamma mRNA, as well as IFN-gamma protein, in cell populations depleted of one of these subsets. Co-culture of cell subsets with total cell populations or depleted ones, on the other hand, leads to severe inhibition of expression of these genes. In these experiments, cells in suppressor subsets exhibit little, if any, expression of IL-2 and IFN-gamma genes. By contrast, depending on donor and lymphoid tissue examined (tonsils or peripheral blood mononuclear cells), CD4, CD8, Leu8, and Leu15 cell subsets are also able to express IL-2 or IFN-gamma genes to high levels. Moreover, in Leu8+ cells that do not express the IFN-gamma gene, extensive expression of both mRNA and protein can be elicited by inhibiting the activation of suppressor cells with gamma-irradiation before induction. These results support the concept that the potential to express or suppress human IL-2 and IFN-gamma genes is not restricted to distinct cell subsets. Suppression or expression can be elicited in cells carrying a given surface marker, depending on the state of the immune system in a lymphoid tissue.