A comparative study of the relative bioavailability of different interferon beta preparations.

BACKGROUND: Three different recombinant interferon beta (IFNbeta) preparations are currently available for the treatment of MS, two IFNbeta-1a products (Rebif and Avonex) and one IFNbeta-1b product (Betaferon). These products differ with respect to the recommended dose, the dosage regimen, and the injection route. This study compared the relative biologic activity of these three products in vitro and in vivo. METHODS: Blood samples were collected from 237 patients with MS (170 on IFNbeta therapy and 67 control subjects receiving no therapy). Samples with neutralizing antibodies were excluded. Levels of the antiviral protein MxA and soluble vascular cell adhesion molecule-1 (sVCAM) in the four groups were measured by ELISA. In the in vitro investigation, untreated blood was incubated for 24 hours with increasing concentrations of the three IFNs from a dose of 1 IU/mL to 1000 IU/mL, after which levels of MxA were measured. RESULTS: A difference between the groups was observed in vitro, with a significant change from baseline in MxA levels being observed at 10 IU for Betaferon compared with 100 IU for Rebif and Avonex. However, this might be due to the different methods used for the determination of IU by the manufacturers. At the single-dose level there were no significant differences between IFNbeta preparations. In vivo, there were significantly different levels of MxA in the four groups. In the Betaferon group, the median value for MxA was 2.29 ng/105 peripheral blood leukocytes (PBL), compared with 1.00 ng/105 PBL for Rebif, 0.57 ng/105 PBL for Avonex, and 0.14 ng/105 PBL for the control group. Some significant differences between the groups were also apparent with respect to levels of sVCAM, which were higher with Betaferon than with Rebif. CONCLUSION: IFNbeta-1b induces higher levels of the above markers of IFNbeta bioactivity than either of the two IFNbeta-1a preparations. Moreover, there is a less striking difference between the two IFNbeta-1a preparations in favor of subcutaneous IFNbeta-1a.

Bioavailability of interferon beta 1b in MS patients with and without neutralizing antibodies.

BACKGROUND: Neutralizing antibodies (NAB) to interferon beta (IFNbeta) occur in about one-third of MS patients treated with IFNbeta-1b and there is an association with a loss of clinical and MRI efficacy. However, there are no data regarding the bioavailability of IFNbeta-1b in patients with and without NAB. METHODS: The authors measured MxA in whole blood by ELISA, and serum-binding antibodies (SBA) by Western blot and ELISA in 134 samples of MS patients on IFNbeta-1b and 54 control subjects, and correlated the MxA levels and SBA titers with the NAB titer. RESULTS: In the IFNbeta group 84 samples were NAB negative, 21 were NAB positive (i.e., titer of > or =20), and 29 had detectable NAB (i.e., titer between 10 and 20). The median MxA concentration in NAB-negative patients was 4.09 ng/10(5) peripheral blood leukocytes (PBL), 2.37 ng/10(5) PBL in samples with detectable NAB, 0.36 ng/10(5) PBL in NAB-positive samples, and 0.27 ng/10(5) PBL in control subjects. There was no significant difference between NAB-positive samples and control subjects, otherwise the groups differed significantly from each other. SBA occurred in 49% of NAB-negative samples, in 79% of samples with detectable NAB, and in all NAB-positive samples. With regard to the SBA titer, all groups differed significantly from each other. In none of the control samples were SBA detected. CONCLUSION: The conversion of SBA into NAB depends to some degree on the SBA titer, but other mechanisms may be involved. Once NAB have developed, the bioavailability of IFNbeta as measured by MxA is completely inhibited.

Lyme encephalopathy: long-term neuropsychological deficits years after acute neuroborreliosis.

We studied long-term cognitive deficits in 20 patients with previously diagnosed Lyme borreliosis several years (average 51.6 months) after their acute phase of illness. Compared with an age- and education matched control group Lyme patients revealed deficits of verbal memory, mental flexibility, verbal associative functions and articulation, but performed adequately on tests of intellectual and problem solving skills, sustained attention, visuoconstructive abilities and mental speed. The late cognitive outcome was unrelated to disease variables from the acute stage of illness, but also to the interval elapsed since infection with B. burgdorferi. These and similar observations (Krupp et al. 1991) suggest that the so-called Lyme encephalopathy may be associated with a long-lasting neuropsychological deficit predominantly affecting mnestic functions.

Neopterin production and tryptophan degradation in acute Lyme neuroborreliosis versus late Lyme encephalopathy.

Fourteen patients with Borrelia burgdorferi infection were investigated for possible abnormalities of tryptophan and neopterin metabolism. Four patients (2 were investigated before therapy, 2 when therapy had been already started) had acute Lyme neuroborreliosis, and 10 patients were investigated months to years after an acute infection. Increased concentrations of neopterin and of the tryptophan-degradation product, L-kynurenine, were detected in the cerebrospinal fluid of patients with acute Lyme neuroborreliosis; one patient presented with subnormal tryptophan. Similar but less marked changes were seen in the treated patients and in some of the patients with Lyme encephalopathy. No such abnormalities were seen in the serum of the patients. The data indicate a role of the immune system and particularly of endogenously formed cytokines, like interferon-gamma and tumour necrosis factor-alpha, effecting tryptophan and neopterin metabolism in patients with acute Lyme neuroborreliosis.