Impaired IgG synthesis in patients with the nephrotic syndrome.

Immunoglobulin synthesis by pokeweed mitogen-stimulated lymphocytes from 62 nephrotic patients and 18 healthy controls was studied. Defective IgG production was observed in patients with the nephrotic syndrome related to minimal change disease, mebranous glomerulonephritis and membranoproliferative glomerulonephritis. The mean values of in vitro IgG synthesis were 20%, 61% and 32%, respectively, of that obtained in the control group. At the same time, serum IgG levels were significantly decreased in each group of patients. In minimal change disease, reduced IgG production and serum levels were fully reversible after recovery (off steroid therapy). The data indicate that a cellular defect of antibody production is a common and eventually transitory phenomenon associated with the acquired hypogammaglobulinemia found in patients with a variety of glomerulopathies.

New protein reagents. Synthesis and properties of halogenated maleimides and isomaleimides.

The title compounds were investigated as examples of potential hetero-bifunctional protein reagents having an electrophilic moiety in addition to a maleimide or isomaleimide ring. The synthesis of such products by cyclization of the corresponding maleamic acids gives lower yields in the maleimide than in the isomaleimide series, especially when the second function is labile, owing to the more drastic reaction conditions necessary to form the symmetric isomer. On the other hand, a comparison of the isomeric imides showed that despite some differences in reactivity, isomaleimides can be used instead of maleimides for chemical modification of proteins. Therefore, if the synthesis of new maleimide reagents containing a second fragile functional group is difficult, they can be designed in the isoimide form.