Treatment with natural human interferon alpha of a CML-patient with antibodies to recombinant interferon alpha-2b

Serum interferon (IFN)-neutralizing antibodies and bioactivities of IFNs in patients with severe type II essential mixed cryoglobulinemia

The efficacy of alpha interferon (IFN-alpha) in the treatment of severe type II essential mixed cryoglobulinemia (EMC) has been reported previously. In some patients, the development of neutralizing antibodies to recombinant IFN-alpha (rIFN-alpha) can affect the clinical response achieved with rIFN-alpha; a second treatment with natural IFN-alpha preparations may reinduce the clinical response. In the present study the ability of leukocyte IFN (LeIFN) to restore the response was investigated from a pharmacodynamic viewpoint. Specifically, the pharmacodynamic profiles of different IFN-alpha preparations were studied by measuring the serum neopterin levels and the levels of expression of protein MxA mRNA in in vivo peripheral blood mononuclear cells in two patients with EMC whose resistance to rIFN-alpha2a treatment increased concomitantly with the development of neutralizing antibodies. These markers were measured before injection and at 24 and 48 h after a single injection of rIFN-alpha2a, consensus IFN [(C)IFN], or LeIFN. No increase or only a slight increase in MxA mRNA levels was detectable after administration of rIFN-alpha2a or (C)IFN, whereas a significant increase (>/=10-fold) in MxA mRNA expression was recorded following administration of LeIFN. The neutralizing antibodies to rIFN-alpha2a cross-react with (C)IFN. Sera from these patients neutralized most but not all of the subtypes present in the natural IFN-alpha (LeIFN) mixture, and no significant increase in neopterin levels was observed after these patients were switched to LeIFN treatment. In summary, the data demonstrate that the problem of neutralizing antibodies still exists and that LeIFN may induce an increase in the level of MxA mRNA expression but not an increase in neopterin levels in patients who are resistant to treatment with rIFN-alpha2a or (C)IFN.

IFN-alpha antibodies in patients with age-related macular degeneration treated with recombinant human IFN-alpha2a

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.

Natural leukocyte interferon-alpha therapy in patients with chronic granulocytic leukemia who have antibody-mediated resistance to treatment with recombinant interferon-alpha

Two patients with chronic-phase chronic granulocytic leukemia initially responded to recombinant interferon alpha-2a (rIFN-alpha-2a) but relapsed as a result of development of hightiter neutralizing antibodies to rIFN-alpha-2a. Both patients were subsequently treated with natural leukocyte IFN-alpha (IFN-alpha-n3), and one of the two patients achieved a durable second hematologic and cytogenetic remission. IFN-alpha-n3 may be considered for patients in whom antibody-mediated resistance to rIFN-alpha-2a develops.

Neutralising antibodies in patients with multiple myeloma receiving maintenance therapy with interferon alpha 2b

In a study of 29 patients who were receiving or had received interferon alpha 2b (IFN-alpha 2b) as maintenance therapy for multiple myeloma, antibodies were detected in 58% (17/29) of patients measured by a solid-phase enzyme-linked immunosorbent assay (ELISA). Only 7/17 patients who were positive for antibody in the ELISA had neutralising antibody to IFN-alpha 2b, measured by virus growth inhibition. These patients comprised six who were receiving IFN-alpha 2b at the time of assessment and one who had finished treatment. Among patients who were receiving the cytokine, four had progressive disease, one was in complete remission and one in partial remission. Neutralising activity was also detected to natural human leucocyte IFN-alpha in the same patients. Two patients who were positive for neutralising antibody remain in remission and are continuing to receive IFN-alpha 2b. These two patients have since lost their neutralising titre. No neutralising antibody to IFN-alpha 2b or natural human leucocyte IFN-alpha was detected in serum from six normal donors. The data suggest that neutralising antibody formation in patients with multiple myeloma is not responsible for relapse in patients receiving IFN-alpha 2b. The transient nature of neutralising antibody production in patients who remain in remission suggests that this response to IFN-alpha 2b is not associated with memory B cells.

Leukocyte interferon in the treatment of chronic myelogenous leukemia in second chronic phase

Four patients with Philadelphia chromosome positive CML were treated with 18-42 x 10(6) IU of purified natural leukocyte IFN-alpha per week, after high-dose chemotherapy for blast phase and attainment of 2nd chronic phase. The second blast phase occurred within 3 months in 3 patients, but one patient is still in second chronic phase after 22 months of treatment. Treatment consisted of interferon only during the first year, and interferon in combination with hydroxyurea during the second year. During the second year suppression of the Philadelphia chromosome was seen in one patient, with 20% Philadelphia negative bone marrow metaphases. The toxicity of purified natural leukocyte IFN-alpha was similar to the toxicity of recombinant IFN-alpha. Antibodies to IFN-alpha were not detected in any patient.

A sensitive antiviral neutralization bioassay for measuring antibodies to interferons

An improved bioassay for measuring neutralizing antibodies to interferons (IFN) is described. The assay is based upon an objective and precise quantification of the viral cytopathic effect. This effect is measured via the dehydrogenase-system in cells, and quantified spectrophotometrically. Virus-infected cells, in contrast to non-infected cells, possess low enzyme activity resulting in low OD signals. This fall in OD can be prevented by the addition of a small, but fixed amount of IFN before the addition of virus. Anti-IFN sera will neutralize the protective effect of IFN. This effect can be quantified by measurement of the reduction in the OD signals. Antibodies to recombinant IFN were found to cross-react with human leukocyte IFN although to a ten-fold lower degree. The assay requires no expensive reagents, it is performed in 96-well microtrays and the results can be measured in an ordinary ELISA scanner. The assay is highly reproducible, yielding inter- and intra-assay variability of less than 10%. The sensitivity is much higher than that reported previously for the CPE technique and that of ELISA techniques.

Chronic myeloproliferative disorders in bone marrow biopsies

This Diagnostic Seminar intends to announce that CMPDs can be classified from BMB histologically by a rather simple system, which can be applied by interested histopathologists successfully. The rationale of this classification is to stay within the groups of diseases which are outlined by clinical findings including the peripheral blood and bone marrow smears. The concept of traditional classification as given by the WHO and textbooks, however, has to be revised as follows (1) Primary diseases of CMPDs must be distinguished from advanced disorders. Primary diseases are CML, P. vera, Thrombocythemia, CMGM, and unclassifiable CMPD. (2) Idiopathic, primary myelosclerosis of the bone marrow is a reactive feature consecutive to neoplastic transformation of hematopoiesis, i.e. myeloproliferation. (3) Advanced disorders comprise (3.1.) excess of blasts and blast crisis, and (3.2.) early myelosclerosis, myelosclerosis and myelofibrosis, advanced myelofibrosis. Advanced disorders are designated by a composed term classifying them among the groups of primary disease and specifying the advanced stage by a suffix, so that the underlying disease remains coining the term, even in unclassifiable cases in which only CMPDs can be applied. (4) The CML group must be subtyped into CML of common type versus that with increase or predominance of megakaryocytes. By this system of classification, it seems possible to classify and type the spectrum of variations occurring among CMPDs to a satisfying result.