Discussion The histological findings specific to CG can be summarized as follows [1, 10]. LM shows glomerular lobulation with infiltration of monocytes into the capillary spaces and large deposits (referred to as thrombi). On IF, staining for IgM is often more intense than that for IgG. EM reveals EDD in the subendothelial and mesangial areas that are characterized by thick-walled microtubular or annular structure measuring 30 nm in diameter. In the present study, large thrombus-like deposits specific to CG were confirmed in 4 out of 9 patients from the cryo-positive SGC-CBP30 mouse group, and thick-walled microtubular structures were seen in the EDD of 5 patients. IgM-dominant

staining was also seen, consistent with previous reports. Eight out of 9 patients were type 1, and 1 patient was type 3. There has been little information available about the differences between type 1 and type 3 MPGN. The majority of patients with MPGN are reported to be children between the ages

of 8 and 16 years, and type 1 occupies 90 % of MPGN [3, 8, 9]. Type 3 MPGN has been reported to occur in a small number of children and young adults, and it has clinical features quite similar to those of type 1 MPGN. The characteristic IF pattern of type 1 MPGN is peripheral granular to band-like staining for C3, with staining for immunoglobulins such as IgG, IgM, and IgA also being seen. Type 3 MPGN has similar features to type 1 MPGN. The above-mentioned features of MPGN are based upon buy Torin 1 reports published before testing for HCV was routine [3, 8, 9], and there have only been a few detailed studies of true HCV-negative MPGN [12]. In the present study, patients with type 1 idiopathic MPGN were younger, had more severe hypocomplementemia, and had less proteinuria compared with type 3 patients. Recently, Nasr et al. reported a novel Cell Cycle inhibitor disease entity that is termed proliferative STK38 glomerulonephritis with monoclonal IgG deposits (PGNMID). Some of the immune-complex glomerulonephritides such as MPGN with IgG deposition are monoclonal, and staining reveals only a single subclass of IgG and a single light-chain isotype, which is most commonly IgG3 kappa. However, the majority of patients do not have

an M-spike or a plasma cell dyscrasia. This type of monoclonal disease affects adults and is more common in white females [13]. In the future, when the position of PGNMID in relation to idiopathic MPGN is reviewed, accumulation of more information about idiopathic MPGN without cryo or HCV positivity may lead to re-evaluation of the relationship between these diseases. Sethi et al. and Bomback, and Appel proposed a new classification of MPGN according to whether it was immunoglobulin-positive or -negative by IF [14, 15]. Immunoglobulin-positive MPGN suggests activation of the classical pathway and they divided it into infections (including HCV), immune complex diseases including lupus nephritis, neoplasms, and others based on the underlying cause of antigenemia.