IgG4-related disease is a new disease classification established in Japan in the 21st century. Patients with IgG4-related disease display hyper-IgG4-gammaglobulinemia, massive infiltration of IgG4+ plasma cells into tissue, and good response to glucocorticoids. Since IgG4 overexpression is also observed in other disorders, it is necessary to diagnose IgG4-related disease carefully and correctly. We therefore sought to determine cutoff values for serum IgG4 and IgG4/IgG and for IgG4+/IgG+ plasma cells in tissue diagnostic of IgG4-related disease. Patients and Methods. We retrospectively analyzed serum IgG4 concentrations and IgG4/IgG ratio and IgG4+/IgG+ plasma cell ratio in tissues of 132 patients with IgG4-related disease and 48 patients with other disorders. Result. Serum IgG4 >135  mg/dl demonstrated a sensitivity of 97.0% and a specificity of 79.6% in diagnosing IgG4-related disease, and serum IgG4/IgG ratios >8% had a sensitivity and specificity of 95.5% and 87.5%, respectively. IgG4+cell/IgG+ cell ratio in tissues >40% had a sensitivity and specificity of 94.4% and 85.7%, respectively. However, the number of IgG4+ cells was reduced in severely fibrotic parts of tissues. Conclusion. Although a recent unanimous consensus of all relevant researchers in Japan recently established the diagnostic criteria for IgG4-related disease, findings such as ours indicate that further discussion is needed.

The authors conclude that multicentric Castleman's disease sometimes occurs with abundant IgG4-positive cells and elevated serum IgG4 levels. Therefore, the two diseases cannot be differentially diagnosed by immunohistochemical staining alone. Laboratory findings, especially IL-6 level, C-reactive protein level and platelet count, are important for the differential diagnosis of the two diseases.

Multicentric Castleman's disease (MCD) is a polyclonal lymphoproliferative disorder that manifests as marked hyper-γ-globulinemia, severe inflammation, anemia, and thrombocytosis. Recently, Takai et al. reported a new disease concept, TAFRO syndrome, named from thrombocytopenia, anasarca, fever, reticulin fibrosis, and organomegaly. Furthermore, Kojima et al. reported Japanese MCD cases with effusion and thrombocytopenia (Castleman-Kojima disease). Here, we report two cases of MCD associated with marked pleural effusion, ascites, and thrombocytopenia, and discuss the independence of the TAFRO syndrome (Castleman-Kojima disease). Case 1: A 57-year-old woman had fever, anemia, anasarca, and some small cervical lymphadenopathy. Although she had been administered steroid therapy, and full-coverage antibiotics, her general condition, including fever, systemic inflammation, and anasarca, deteriorated steadily. We administered chemotherapy [CHOEP (cyclophosphamide, doxorubicin, vincristine, etoposide, and prednisolone) regimen], but despite a transient improvement, she died due to septic shock. Case 2: A 73-year-old man with a history of aplastic anemia and remission presented with fever, severe inflammation, and anasarca. Prednisolone was administered (15 mg daily), and his hyperinflammation once improved. Nevertheless, his general condition, including pleural effusion and ascites, worsened, and C-reactive protein and interleukin-6 levels showed marked increases. The patient died due to multiorgan failure. Cases of TAFRO syndrome (Castleman-Kojima disease) are still rare. Therefore, it is necessary to conduct multicenter clinical surveys including similar cases, such as ours, to reach a consensus regarding diagnostic criteria, therapeutic strategy, and pathophysiological etiology for this syndrome.

Three newborn infants who developed hyperbilirubinemia due to blood group incompatibility were treated with high-dose gammaglobulin. Hyperbilirubinemia was caused by Rhesus (Rh) incompatibility (anti-E + anti-c) in Infant 1 and ABO incompatibility (anti-B) in Infants 2 and 3. Hyperbilirubinemia was refractory to conventional phototherapy but responded well to intravenous gammaglobulin (IVGG) at a dose of 1 g/kg in all infants. No adverse effects were observed. These findings suggest that high-dose IVGG may be useful in the treatment of hyperbilirubinemia due to isoimmune haemolytic disease resistant to phototherapy.

Membrane microdomains consisting of sphingomyelin (SM) and cholesterol appear to be important for signal transduction in T-cell activation. The present study was designed to elucidate the role of membrane SM in vivo and in vitro using sphingomyelin synthase 1 (SMS1) knock out (SMS1(-/-)) mice and Concanavalin A (ConA)-induced hepatitis. After establishing SMS1(-/-) mice, we investigated CD4+ T-cell functions including proliferation, cytokine production and signal transduction in vivo. We also examined severity of hepatitis, cytokine production in serum and liver after ConA injection at a dose of 20 mg kg(-1). CD4+ T cells from SMS1(-/-) mice showed severe deficiency of membrane SM and several profound defects compared with wild-type controls as follows: (i) cellular proliferation and production of IL-2 and IFN-γ by co-cross-linking of CD3 and CD4; (ii) tyrosine phosphorylation of LAT and its association with ZAP-70; (iii) clustering and co-localization of TCR with lipid rafts. Consistent with these impaired CD4+ T-cell functions in vitro, SMS1(-/-) mice showed decreased serum levels of IL-6 and IFN-γ by ConA injection, which renders SMS1(-/-) mice less sensitive to ConA-induced hepatitis. These results indicated that the deficiency of membrane SM caused the CD4+ T-cell dysfunction through impaired lipid raft function contributed to protection of ConA-induced liver injury, suggesting that the membrane SM is critical for full T-cell activation both in vitro and in vivo.