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.

Dual control of human interleukin-2 and interferon-gamma gene expression by histamine: activation and suppression.

Histamine is considered to be an activator of cells with suppressive capacity. In agreement with this concept, we show that histamine elicits a strong inhibition of the induced expression of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) genes. However, our experiments reveal a novel property of histamine: early in the induction process, it strongly stimulates expression of these two genes in cultured human peripheral blood mononuclear cells (PBMC). The histamine-mediated superinduction of IL-2 mRNA is seen also in a Th cell line, showing that such cells respond directly to histamine. In the course of mitogenic induction, a 20-fold stimulation by histamine is converted into an equally strong inhibition. The response of a PBMC population to histamine thus undergoes a remarkable change following T cell activation. The dual effect of histamine can be blocked by the H2 histamine receptor antagonist cimetidine, while the early activation by histamine is mimicked by the H2 agonist impromidine, showing that both activation and inhibition of IL-2 and IFN-gamma gene expression by histamine are exerted via this receptor. These results support the concept that histamine, released during an immune response, exerts opposite regulatory effects by first activating cells able to express the IL-2 and IFN-gamma genes and only then suppressive cells that become responsive to histamine more slowly, but once activated shut off the expression of these genes.

Transient expression of human interleukin-2 and interferon-gamma 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.

Interleukin-2 induces an early step in the activation of interferon-gamma gene expression.

Establishment of protective immunity depends critically on IFN-gamma. We show that in human peripheral blood mononuclear cells, low doses of IL-2 greatly potentiate the response of the IFN-gamma gene to mitogen, by over 100-fold. By itself, IL-2 is unable to induce IFN-gamma mRNA to a significant extent. Yet, exposure to IL-2 leads to cellular commitment within a few hours, expressed by greatly enhanced accumulation of IFN-gamma mRNA upon subsequent exposure to phytohemagglutinin. Changes induced by IL-2 do not relieve the requirement for de novo protein synthesis during the early phases of induction of IFN-gamma gene expression. IL-2 may induce a component essential for induction of IFN-gamma mRNA that is utilized during subsequent exposure to a mitogenic signal. Our results demonstrate synergy between IL-2 and mitogen in IFN-gamma gene induction.

Is cord blood erythropoietin a marker of intrapartum hypoxia?

A sensitive assay was used to compare the biological activity of cord serum erythropoietin in two groups of infants born with or without labor-induced hypoxia. The mean cord serum erythropoietin activity in 161 infants delivered after vaginal labor was 116 +/- 36 mU/mL, and was indistinguishable from that observed in 23 infants delivered by preplanned, elective cesarean section, 114 +/- 12 mU/mL (P = .75). The bioassay measured effective erythropoietin activity, including the contribution of potentiators in serum. These results indicate that duration and intensity of labor are insufficient to cause a significant increase in effective erythropoietin activity.

A constitutive antibody in normal human serum directed against rabbit bone marrow cells: lack in parturients, neonates, and hematologic disorders.

Normal human serum effectively inhibits a bioassay for erythropoietin based on DNA synthesis by rabbit erythroid precursors. This heat-sensitive inhibitory activity is readily lost on dilution of serum, revealing the presence of erythropoietin-potentiating activity. Inhibitory activity is caused by a rapid cytotoxic effect on rabbit bone marrow cells; mouse cells are less sensitive. Cytotoxic activity is removed from serum by adsorption to protein A, is not expressed at 4 degrees C, and is neutralized by anti-C3c complement antibody. Cytotoxicity is inhibited by EGTA; the effect of EGTA is reversed by addition of Ca2+ ions. These findings show that cytotoxicity is exerted through an antibody via the classical pathway of complement-dependent cell lysis. Although serum from healthy, adult human donors consistently contains cytotoxic activity, no such activity is observed in most serum samples from neonates, parturients, and patients with severe anemia. Patients with polycythemia or chronic renal failure occasionally lack cytotoxic activity in their serum. Serum samples lacking cytotoxic activity were found to be deficient in the antibody component in 34 out of 35 cases examined. These results show that an antibody directed against rabbit cells is constitutively present in normal human serum but is absent in a number of pathologic situations as well as being absent in neonates and parturients.

The potential to express or suppress human interleukin-2 and interferon-gamma 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.