Research on the correlation of mannose binding lectin (MBL) with diabetes MBLlitus and arteriosclerosis

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We examined sera of known MBL genotype by gel-filtration and assesed their elution patterns using an ELISA for MBL and identified two MBL forms, a high molecular weight form and a lower molecular weight form. By the identification of either or both forms in individual sera, three types of patterns emerged: type I consisted of a high molecular form; type 2, of a low molecular form; and type 3, of both forms. Types 1, 2 and 3 corresponded, respectively, to a wild type (A/A), a homozygous mutation at codon 54 (BIB) and their heterozygote (A/B). Binding to mannan and MASP-1/3 occurred exclusively with the high molecular form. An apparent MBL deficiency does not in fact represent a deficiency in MBL molecules but rather the presence of circulating oligomeric mutant MBL with impaired function.Binding ability of MBL with various immunoglobulins was investigated. Among the immunoglobulins, quite a few myeloma IgA showed binding capacity with MBL, and most of them exhibited very weak or no capacity. The binding of the IgAs with MBL was confirmed to be through carbohydrate moieties. The immunoglobulins with weak or no binding capacity with MBL became reactive with MiIBL when they were treated with sialidase and galactosidase, indicating that exposure of mannose and/or n-acetylglucosamine is necessary in the reaction with MBL. It was suggested that some IgAs with some special sugar constitution might play a part in an occur-rence of IgA nephropathy associated with MBL-deposition.The change of the serum MBL level in oxidative stress by oral administration of carbon tetrachioride to rat was inves-tigated. Although the MBL level was severely decreased immediately after the administration possi-bly due to hepatic capacity of carbon tetrachloride, it recovered to the previous level within two to three days. Rapid elevation of MBL level by oxidative stress was not observed in the case using carbon tetrachloride.