Effect Of IFN-alpha Treatment Research Articles

Soluble MIC is elevated in the serum of patients with pancreatic carcinoma diminishing γδ T cell cytotoxicity

Intestinal cells express MHC related molecules termed MICA/MICB, which are up-regulated under stress and in many gastrointestinal tumors. These molecules can be recognized by the immunoreceptor NKG2D, which is present on NK and gammadelta T cells. Release of MIC molecules from the cell surface is thought to constitute an immune escape mechanism of tumor cells. The immediate effect of soluble MIC (sMIC) on cellular cytotoxicity of gammadelta T cells is yet not investigated. We determined sMIC levels in sera of patients with pancreatic carcinoma and the expression of MIC on the surface of tumor cells by FACS. The effect of sMIC content in patient serum on cellular cytotoxicity of gammadelta T and NK cells was investigated by cytotoxicity assays. Subsequently, the effect of IFN-alpha treatment on MIC expression, release and cellular cytotoxicity was investigated. Pancreatic carcinoma cells express MIC, and patient sera contain elevated sMIC levels that correlate with tumor stage and differentiation. Furthermore, cellular cytotoxicity of gammadelta T cells and NK cells against pancreatic carcinoma is impaired by sMIC in patient sera which is prevented by sMIC neutralization. Incubation of pancreatic cancer cells with IFN-alpha increases MIC expression without induction of sMIC resulting in enhanced lysis of tumor cells. Our results demonstrate that sMIC impairs NKG2D-mediated immunity against pancreatic carcinoma by directly diminishing cytotoxicity of gammadelta T cells and NK cells. IFN-alpha, which is used in adjuvant treatment of pancreatic carcinoma, might partly act via up-regulation of MIC without induction of sMIC release.

IFN-α Antibodies in Patients with Age-Related Macular Degeneration Treated with Recombinant Human IFN-α2a

We tested for development of binding and neutralizing antibodies to interferon-alpha (IFN-alpha) during IFN-alpha2a therapy of patients with age-related macular degeneration (AMD) of the eyes. Antibodies were investigated retrospectively in sera of 34 patients treated with 3 x 10(6) IU IFN-alpha2a (Roceron-A), Hoffmann La-Roche, Basel, Switzerland) three times weekly for periods of 8-16 weeks with or without a drug-free 4-12-week intermission. Additionally, 10 patients were investigated prospectively; 7 received 1.5-6 x 10(6) IU IFN-alpha2a three times weekly for 12 months, and 3 received placebo. Binding antibodies were tested by molecular size and protein G affinity chromatography using 125I-IFN-alpha2a. Neutralizing activities were tested by antiviral neutralization bioassay. IgG antibodies were detected in 24 of 34 IFN-alpha2a-treated patients (71%). Significantly higher anti-IFN-alpha levels were observed in patients who after discontinuation were readministered IFN-alpha2a (p < 0.02). Three of the IFN-alpha2a-treated patients in the prospective study had high and 1 had low antibody titers. Neutralizing antibody titers were high against IFN-alpha2a and IFN-alpha2c and low against lymphoblastoid and leukocyte IFN-alpha. Impaired clinical responses were observed in antibody-positive patients (p < 0.01). The development of neutralizing anti-IFN-alpha antibodies in patients with AMD during recombinant human IFN-alpha therapy may explain the often poor clinical effect of IFN-alpha treatment.

Molecular mechanisms underlying interferon-alpha-induced G0/G1 arrest: CKI-mediated regulation of G1 Cdk-complexes and activation of pocket proteins.

One prominent effect of IFNs is their cell growth-inhibitory activity. The mechanism behind this inhibition of proliferation is still not fully understood. In this study, the effect of IFN-alpha treatment on cell cycle progression has been analysed in three lymphoid cell lines, Daudi, U-266 and H9. Examination of the growth-arrested cell populations shows that Daudi cells accumulate in a G0-like state, whereas U-266 cells arrest later in G1. H9 cells are completely resistant to IFN-alpha's cell growth-inhibitory effects. The G0/G1-phase arrest is preceded by a rapid induction of the cyclin-dependent kinase inhibitors (CKIs), p21 and p15. In parallel, the activities of the G1 Cdks are significantly reduced. In addition to p21/p15 induction, IFN-alpha regulates the expression of another CKI, p27, presumably by a post-transcriptional mechanism. In the G1 Cdk-complexes, there is first an increased binding of p21 and p15 to their respective kinases. At longer exposure times, when Cdk-bound p15 and p21 decline, p27 starts to accumulate. Furthermore, we found that IFN-alpha not only suppresses the phosphorylation of pRb, but also alters the phosphorylation and expression of the other pocket proteins p130 and p107. These data suggest that induction of p21/p15 is involved in the primary IFN-alpha response inhibiting G1 Cdk activity, whereas increased p27 expression is part of a second set of events which keep these Cdks in their inactive form. Moreover, elevated levels of p27 correlated with a dissociation of cyclin E/Cdk2-p130 or p107 complexes to yield cyclin E/Cdk2-p27 complexes. In resistant H9 cells, which possess a homozygous deletion of the p15/p16 genes and lack p21 protein expression, IFN-alpha causes no detectable changes in p27 expression and, furthermore, no effects are observed on either pocket proteins in this cell line. Taken together, these data suggest that the early decline in G1 Cdk activity, subsequent changes in phosphorylation of pocket proteins, and G1/G0 arrest following IFN-alpha treatment, is not primarily due to loss of the G1 kinase components, but result from the inhibitory action of CKIs on these complexes.

Induction of Cip/Kip and Ink4 cyclin dependent kinase inhibitors by interferon-alpha in hematopoietic cell lines.

One prominent effect of IFNs is their cell growth inhibitory activity. The exact molecular mechanism behind this inhibition of proliferation remains to be elucidated. Possible effectors for IFN-induced growth inhibition are the recently discovered cyclin-dependent kinase inhibitors. The effect of IFN-alpha treatment on the members of the Ink4 and Cip/Kip families of Cdk inhibitors was investigated in three hematopoietic cell lines Daudi, U-266 and H9. Two of these cell lines, Daudi and U-266, respond to IFN-alpha by G1 arrest, whereas the H9 cell line is not growth arrested by IFN-alpha. We show that a p53-independent upregulation of p21 mRNA occurs following IFN-alpha treatment in all three cell lines. In Daudi and U-266 cells, the mRNA induction is accompanied by an increase in p21 protein, followed by an increased binding of p21 to Cdk2 and a subsequent decrease in Cdk2 activity, temporally coinciding with G1 arrest. In both these cell lines, there was also an increased binding of p21 to Cdk4. In contrast, p21 protein was not expressed in H9 cells, despite high levels of p21 mRNA following IFN-alpha treatment. In U-266 cells, IFN-alpha increased not only p21 but also p15 mRNA and protein levels, followed by an increased association of p15 with Cdk4. Furthermore, IFN-alpha treatment caused a four- to sixfold induction of the p16 E1beta transcript in U-266 cells. Expression levels of the other Ink4 and Cip/Kip Cdk inhibitors were not induced by IFN treatment in any of the cell lines. We conclude that IFN-alpha can act as a potent regulator of Cdk-inhibitor expression, correlating with decreased Cdk activity and cell growth inhibition. One mechanism for resistance to IFN may be loss of the ability of cells to upregulate these proteins.

Lymphoproliferative responses to hepatitis C virus core, E1, E2, and NS3 in patients with chronic hepatitis C infection treated with interferon alfa

The quality of the hepatitis C virus (HCV)-specific T-cell response may greatly determine the course of an HCV infection. An adequate T-cell response may contribute to a successful clearance of the virus and a rapid recovery from the disease. An inadequate response may lead to viral persistence and may eventually contribute to the pathogenesis of hepatocellular damage in chronic disease. The effect of interferon alfa (IFN-alpha), presently the most popular therapeutic agent for chronic HCV infections, on HCV-specific T-cell responses is completely unknown. To demonstrate the presence of HCV-specific T lymphocytes during chronic HCV infections, to know their antigenic specificities, and to examine possible effects of IFN-alpha treatment on their presence and antigen recognition patterns, we have stimulated peripheral blood mononuclear cells (PBMC) from 35 chronic HCV patients with nine pools of synthetic peptides representing the HCV Core, E1, and E2 proteins as well as with a recombinant NS3 protein. The proliferative responses of PBMC from 16 healthy control subjects toward these antigens were measured for comparison. Lymphoproliferative responses of patients with chronic HCV infections were assayed either before (in 10 patients), during (in 13 patients), or after (in 21 patients) treatment with IFN-alpha. The analysis showed that PBMC from most HCV patients consistently recognized the COOH-terminal part of the core protein. E1, E2, and NS3 were recognized less frequently. This recognition pattern was not related to the therapy with IFN-alpha nor to the clinical response of the patient toward this therapy. The response to the Core protein could be fine-mapped to the COOH-terminal region encompassing amino acids (aa) 73 to 92, 121 to 140, 145 to 164, and 157 to 176. (Hepatology 1996 Jan;23(1):8-16)