What is the role of carohydrates in interferons?

Pulmonary catabolism of interferon-gamma evaluated by lung perfusion of both normal and smoke-exposed rats

The role of the lungs in the catabolism of rat recombinant interferon-gamma, either in normal rats or in rats subjected to an acute cigarette smoking episode, was evaluated using an isolated and perfused lung preparation. After administration of interferon-gamma into the lung perfusion medium, there was no clearance of the cytokine in either control or smoke-exposed rat lungs, and only 0.1 +/- 0.2% of the total dose was recovered in the bronchoalveolar lavage fluid. When the same amount of interferon-gamma was instilled into the bronchial alveolar tree, concentrations of the cytokine in the perfusate increased progressively so that after 3 h up to 71.2 +/- 4.3 and 62 +/- 5.7% of the administered dose, as measured by ELISA test, had been transferred from the bronchial lumen to the perfusion medium of either control or smoke-exposed rat lungs, respectively, the latter values being significantly lower (p < or = 0.05) than those obtained in control lungs. Moreover, total recoveries of interferon-gamma evaluated in smoke-exposed rat lungs (78.4 +/- 8.6%) were also significantly lower than those observed in control rat lungs (91.4 +/- 11.8%). Biologic activity evaluations on the same samples gave values significantly lower than those obtained using ELISA, indicating a partial loss of biologic activity during transalveolar transit. In conclusion, it appears that the transfer of interferon-gamma is almost exclusively unidirectional from the alveolar space to the plasmatic pool, with partial degradation during transalveolar passage.

What roles have anti-interferon antibodies in physiology and pathology?

Until recently the generation of antibodies to interferons (IFNs) was considered an unlikely event, while it is now clear that natural interferons (except IFN-beta) are practically nonimmunogenic, although recombinant interferons give rise to antibodies in about 30% of patients with occasional clinical complications. By realizing that normal individuals display spontaneously traces of IFN autoantibodies, in this review it is suggested that (if immunotherapy has to succeed) new generations of recombinant proteins should be the least antigenic as possible.

Recombinant equine interferon-beta 1: purification and preliminary characterization

Equine interferon-beta 1 (EqIFN-beta 1) was purified from extracts of recombinant Escherichia coli by sequential chromatography on hydroxylapatite, anion-, and cation-exchangers. The resulting protein was greater than 98% pure as determined by sodium dodecylsulfate gel electrophoresis, gel permeation HPLC, and reverse-phase HPLC. Amino-terminal amino acid sequencing revealed that essentially all molecules contained an additional amino-terminal methionine. The specific antiviral activity of EqIFN-beta 1 determined on equine dermal fibroblasts challenged with vesicular stomatitis virus (VSV) was approximately 5 X 10(8) U/mg. Less than 0.001% of this activity was observed in antiviral assays using human (A549), murine (L-M), ovine (SCP), or bovine (MDBK and BT) cells challenged with VSV or encephalomyocarditis virus. A series of monoclonal murine IgG antibodies were developed which neutralize the antiviral activity of EqIFN-beta 1. None of these antibodies nor rabbit antiserum to EqIFN-beta 1 were able to neutralize human IFN-beta; antiserum to human IFN-beta did not neutralize EqIFN-beta 1. Two of the monoclonal antibodies were used to establish a rapid one-step solid-phase enzyme immunoassay for EqIFN-beta 1.

The lymphatic route. V. Distribution of human natural interferon-beta in rabbit plasma and lymph

Human natural interferon-beta (HuIFN-beta) was administered through different routes (intravenous [i.v.], intramuscular [i.m.], and subcutaneous [s.c.]) and its distribution in lymph and plasma was evaluated. After i.v. (bolus) administration the lymph/plasma ratio was about 0.35 but it significantly increased (11-fold) after i.m. administration. Addition of human albumin (ALB) to the IFN solution did not favor IFN absorption through the lymphatics. On the other hand, addition of ALB improved IFN absorption through the lymphatics after s.c. administration. These results are interesting because they clarify why IFN-beta can exert immunomodulatory activities in spite of very low plasma levels.

Ricin-resistant human T-cell hybridomas producing interferon gamma

Ricin-resistant variants of the SH9 T-cell line were selected after growth of this line in medium containing toxic amounts of ricin, a lectin derived from Ricinus communis. The ricin-resistant SH9 lines, SH9.R0 and SH9.R1, were demonstrated to be deficient in cell surface ricin-binding sites, but otherwise had the cellular phenotype of SH9 cells. Ricin-resistant T-cell hybridomas were prepared by fusion of SH9.R0 and SH9.R1 with activated T-lymphocytes. The presence of ricin in the selection medium rapidly killed unfused T-lymphocytes and prevented cell transformation by human T-cell leukaemia virus type 1 (HTLV-1) which is shed by the SH9.R0 and SH9.R1 cells. This ensured that the cells growing out were indeed hybridomas. Ricin-resistant T-cell hybridomas were characterised and also shown to lack cell surface receptors for ricin. Analysis of T-cell surface markers indicated that the T-cell hybridomas could be the result of fusions between SH9.R1 cells and T-helper lymphocytes or T-suppressor lymphocytes. All of the T-cell hybridomas prepared in this study spontaneously produced interferon gamma (IFN gamma).

Evaluation of routes of administration of interferon in cancer: a review and a proposal

Interferons are endowed with antiviral and antitumoral activities; the latter particularly has attracted attention, even though it remains uncertain whether it is preferentially due to a direct antiproliferative effect or to enhancement of host-mediated immune responses. Unfortunately, interferons administered in pharmacological doses produce considerable toxicity that is dose-related and that may require cessation of therapy. The administration of interferon has been carried out mostly by intravenous and intramuscular routes. High serum interferon titers have been expected to correlate with therapeutic efficacy. However, there is no such correlation, and certainly interferon levels in the interstitial fluid of target or effector cells would be more critical and informative. Moreover, because they are rapidly filtered by the kidneys, high serum titers are accompanied by considerable renal loss. Thus, several factors, one of which may be the unsuitability of administration routes, may explain the modest therapeutic efficacy of interferon so far observed in cancer. It must be emphasized that interferons and other biological response modifiers are pharmacodynamically unique substances able to elicit unpredictable responses; effects of these drugs depend on the nutritional and metabolic status and immune responsiveness of the host rather than simply on their plasma levels. After reviewing possible routes of administration, a new one, the lymphatic route, appears of interest. The basic strategy is to shift most of the interferon into the lymph pool minimizing direct absorption into the blood. In this way, the lymph/plasma ratio of interferon concentration will resemble that observed during the physiological response and will be greater than 1. Most of the injected interferon will then interact with the lymphoid system, even though eventually it will slowly drain into the blood pool. If the therapeutic index can be shown to be improved in patients, facilitated lymphatic absorption could become a preferential route for the administration of biological response modifiers.