Interferon alpha associated with systemic lupus erythematosus is not intrinsically acid labile.

The physicochemical properties of apparently acid-labile IFN-alpha from patients with SLE have been studied. The antigenicity, apparent molecular size, and isoelectric point of SLE IFN-alpha are indistinguishable from those of conventional, previously characterized, acid-stable subspecies of IFN-alpha. However, after partial purification by anion-exchange chromatography, SLE IFN-alpha no longer exhibits acid lability, suggesting that other plasma factor(s) are responsible for the acid lability of SLE IFN-alpha. Addition of SLE plasma, but not normal plasma, to conventional acid-stable IFN-alpha renders the exogenous IFN-alpha acid labile. Preliminary results demonstrate that an acid-dependent IFN-inactivating activity can be partially purified from SLE plasma by anion-exchange chromatography.

Genetic mapping of the amino-terminal domain of bacteriophage T4 DNA polymerase.

The DNA polymerase of bacteriophage T4 is a multifunctional enzyme that harbors DNA-binding, DNA-synthesizing and exonucleolytic activities. We have cloned in bacterial plasmids about 99% of the structural gene for this enzyme (T4 gene 43). The gene was cloned in six contiguous 5'-terminal DNA fragments that defined seven intragenic mapping regions. Escherichia coli hosts harboring recombinant plasmids carrying the gene 43 subsegments were used in marker-rescue experiments that assigned a large number of ts and nonsense polymerase mutations to different physical domains of the structural gene. Conspicuously, only one missense mutation in a large collection of mutants mapped in the 5'-terminal 450 base-pair segment of the approximately 2700 base-pair gene. To test if this indicated a DNA polymerase domain that is relatively noncritical for biological activity, we mutagenized a recombinant plasmid carrying this 5'-terminal region and generated new conditional-lethal mutations that mapped therein. We identified five new ts sites, some having mutated at high frequency (nitrosoguanidine hot spots). New ts mutations were also isolated in phage genes 62 and 44, which map upstream of gene 43 on the T4 chromosome. A preliminary examination of physiological consequences of the ts gene 43 mutations showed that they exhibit effects similar to those of ts lesions that map in other gene 43 segments: some were mutators, some derepressed gene 43 protein synthesis and they varied in the severity of their effects on T4-induced DNA synthesis at nonpermissive temperatures. The availability of the gene 43 clones should make it possible to isolate a variety of lesions that affect different activities of the T4 DNA polymerase and help to define the different domains of this multifunctional protein.

Treatment of complicated sarcoidosis with infliximab anti-tumor necrosis factor-alpha therapy.

BACKGROUND: Tumor necrosis factor-alpha (TNF-alpha) may have an important role in the clinical exacerbation of sarcoidosis. OBJECTIVE: To treat sarcoidosis with infliximab, a chimeric human-murine anti-human TNF-alpha monoclonal antibody. DESIGN: Case report. SETTING: U.S. academic medical center. PATIENT: A 72-year-old woman with sarcoidosis presenting with severe protein-losing enteropathy, hypoalbuminemia, and proximal myopathy who had not responded adequately to corticosteroid therapy and whose clinical course was further complicated by acute tubular necrosis and renal failure requiring long-term hemodialysis. INTERVENTION: Intravenous infusion of infliximab, 5 mg/kg of ideal body weight; infusion was repeated at 2 and 6 weeks. MEASUREMENTS: Clinical response of enteropathic and myopathic symptoms and serum albumin level. RESULTS: Enteropathic and myopathic symptoms resolved after infliximab therapy, and the serum albumin level also improved. However, the clinical course was complicated by the development of a hypercoagulable state associated with circulating anticardiolipin antibodies, which prompted discontinuation of infliximab therapy. CONCLUSIONS: Infliximab therapy was successful in a patient with sarcoidosis. Tumor necrosis factor-alpha may be an important mediator of clinical disease in sarcoidosis and could be an attractive target for therapeutic intervention. However, infliximab may cause adverse effects associated with cytokine cascade manipulation.

Adventitial stripping: a digit saving procedure in refractory Raynaud's phenomenon.

OBJECTIVE: To assess the efficacy and role of adventitial stripping (i.e., digital sympathectomy) in patients with severe digital ischemia secondary to refractory Raynaud's phenomenon (RP). METHODS: A retrospective chart review of 13 consecutive cases of adventitial stripping in 9 patients with severe secondary RP was performed, examining patient characteristics, previous therapeutic interventions, and postoperative outcomes. An illustrative case is presented. RESULTS: All identified patients had evidence of systemic disease. After adventitial stripping, sustained longterm improvement was achieved in all 13 ischemic digits, 8 of which showed amelioration of symptoms immediately after surgery. In 2 patients, sustained improvement was noted despite progressive ischemia in nonoperated digits. The mean followup time was 28 months (range 10 to 47). No postoperative complications were observed. Pre-operative sympathetic nerve blockade was performed in 12 of the cases, of which 10 showed no clinical response. Pathologic specimens revealed adventitial fibrosis that caused extrinsic compression of the digital arteries. CONCLUSION: Adventitial stripping of digital arteries is an extremely effective and safe option for patients with severe digital ischemia secondary to refractory RP. The efficacy of this procedure results not only from sympathetic denervation but also from decompression of the ischemic vessel through removal of a fibrotic and noncompliant adventitia. Because of the effects of this extrinsic vascular compression, lack of response to pre-operative sympathetic nerve blockade is not predictive of postoperative outcomes.

Serum activity that confers acid lability to alpha-interferon in systemic lupus erythematosus: its association with disease activity and its independence from circulating alpha-interferon.

We conducted a longitudinal evaluation of a patient with systemic lupus erythematosus who constitutively exhibited elevated levels of circulating alpha-interferon (alpha-IFN). This study demonstrated that the serum levels of an activity that renders the endogenous alpha-IFN acid labile are positively correlated with disease activity. This IFN acid lability-inducing activity can also be found in the sera of systemic lupus erythematosus patients who have active disease but who do not have circulating alpha-IFN.

Association between FcgammaRIIa-R131 allotype and bacteremic pneumococcal pneumonia.

Human FcgammaRIIa has 2 codominantly expressed allotypes, which differ greatly in their ability to ligate immunoglobulin G2 (IgG2). Whereas FcgammaRIIa-R131 binds only weakly to IgG2, FcgammaRIIa-H131 binds to it efficiently and might be primarily responsible for the phagocytosis of IgG2-opsonized bacteria. IgG2 plays a pivotal role in defense against pneumococcal infection. This prospective study showed that 50% of patients with bacteremic pneumococcal pneumonia were homozygous for FcgammaRIIa-R131, compared with 28% with nonbacteremic pneumococcal pneumonia and 29% of uninfected controls (P<.05). The gene frequency of FcgammaRIIa-R131 was 0.67 in bacteremic patients, significantly higher than in the other groups (P<.05). All bacteremic patients who died within 1 week of hospitalization were homozygous for FcgammaRIIa-R131. Therefore, the severity of pneumococcal infection may, in part, be genetically mediated. Taken together with similar findings in cases of meningococcal disease, these results suggest that such genetic factors may be generalizable to infections caused by encapsulated bacteria.

Remission of juvenile rheumatoid arthritis after infection with parvovirus B19.

A 22-year-old Caucasian woman with a 6 year history of persistently active, systemic onset juvenile rheumatoid arthritis (JRA) developed symptoms of headache, dry cough, nausea, vomiting, abdominal pain, diarrhea, and dehydration associated with a high fever, elevated liver enzymes, and lymphopenia. Subsequent investigation revealed acute infection with parvovirus B19. Following clinical improvement over 10-14 days solely with supportive care, her underlying disease remained in remission for about 7 months.

The cytoplasmic domain of human FcgammaRIa alters the functional properties of the FcgammaRI.gamma-chain receptor complex.

The gamma/zeta-chain family of proteins mediate cell activation for multiple immunoglobulin receptors. However, the recognition that these receptors may have distinct biologic functions suggests that additional signaling elements may contribute to functional diversity. We hypothesized that the cytoplasmic domain (CY) of the ligand binding alpha-chain alters the biological properties of the receptor complex. Using macrophage FcgammaRIa as a model system, we created stable transfectants expressing a full-length or a CY deletion mutant of human FcgammaRIa. Both receptors functionally associate with the endogenous murine gamma-chain. However, we have established that the CY of FcgammaRIa directly contributes to the functional properties of the receptor complex. Deletion of the FcgammaRIa CY leads to slower kinetics of receptor-specific phagocytosis and endocytosis as well as lower total phagocytosis despite identical levels of receptor expression. Deletion of the CY also converts the phenotype of calcium independent FcgammaRIa-specific phagocytosis to a calcium-dependent phenotype. Finally, deletion of the CY abrogates FcgammaRIa-specific secretion of interleukin-6 but does not affect production of interleukin-1beta. These results demonstrate a functional role for the CY of FcgammaRIa and provide a general model for understanding how multiple receptors that utilize the gamma-chain can generate diversity in function.