The serum MK level could be a marker of disease activity in RA and an indicator of a poor prognosis. MK may have a role in the pathogenesis of RA via induction of inflammatory mediators.

The main aim of this study is to investigate the pharmacokinetics of infliximab and Fcgamma receptor (FcgammaR) polymorphism in two patients with rheumatoid arthritis (RA) who were well controlled by low-dose infliximab. A 57-year-old woman (Patient 1) and a 67-year-old woman (Patient 2) had active RA despite methotrexate and prednisolone treatments. They improved after the addition of infliximab (3 mg/kg), but developed pneumonia and sepsis, respectively. Although the infliximab doses were reduced to 1.5 mg/kg and 1 mg/kg, respectively, clinical improvements were maintained. Blood samples were obtained at 1 h after infliximab administration and at eight weeks (just before the next dose). The elimination half-life was determined by the serum concentration of infliximab. We also analyzed the polymorphisms of FcgammaRIIA, FcgammaRIIIA, and FcgammaRIIIB for the genomic DNA samples from the two patients and three controls. Amplification of the FcgammaR-genomic regions in allotype-specific polymerase chain reactions was used to distinguish the genotypes. Decresed clearance of infliximab was proven by a pharmacokinetic study of these patients under low-dose infliximab therapy. 131H/H (FcgammaRIIA) and 176F/F (FcgammaRIIIA) were detected in both patients. NA1/NA2 and NA2/NA2 (FcgammaRIIIB) were detected in Patients 1 and 2, respectively. These patients were well controlled over the long term by low-dose infliximab. The mechanism of the reduced clearance of infliximab might possibly be explained in part by the FcgammaR polymorphisms.

Pneumothorax is a rare pleuropulmonary manifestation of systemic lupus erythematosus. We encountered a 37-year-old Japanese woman who had systemic lupus erythematosus complicated by recurrent pneumothorax during treatment for recurrent serositis with glucocorticoid therapy. She was admitted for the third episode of lupus peritonitis in December 2005. Intravenous cyclophoshamide and increased dose of oral prednisolone were administered. In early January 2006, hemoptysis was observed and bronchofiberscopy revealed hemorrhage from the left lower lobe. After intravenous methylprednisolone pulse therapy and oral cyclosporine therapy were added, pleurisy and pulmonary hemorrhage improved. On February 22nd, she suddenly developed pneumothorax on the right side, followed by pneumothorax on the left side after 2 days. This pneumothorax on the left side did not improve despite chest tube drainage for over one month. She underwent thoracoscopic partial lobectomy of lower lobe of the left lung, and her symptoms improved. Review of the literature identified 10 case reports of systemic lupus erythematosus complicated by pneumothorax. All of the patients including our case had underlying pulmonary lesions, and 9/11 patients had pleurisy. Besides 10/11 patients received glucocorticoid therapy before the occurrence of pneumothorax. Tissue fragility caused by these factors might contribute to the complication of pneumothorax in patients with systemic lupus erythematosus.

Adult-onset Still's disease (AOSD) is a systemic inflammatory disease of unknown etiology. A 44-year-old male patient presented with AOSD complicated by macrophage activation syndrome after etanercept therapy. His serum tumor necrosis factor-α (TNF-α) level was increased dramatically after etanercept therapy. The clinical course of this case suggests that the increased TNF-α level by etanercept administration might cause macrophage activation syndrome in this case.

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