Increased concentrations of total IgM at clinical onset of type 1 (insulin-dependent) diabetes: correlation with IgM binding to cells. The Belgian Diabetes Registry.
Eighty patients with type 1 (insulin-dependent) diabetes (ages 0-39 years) were consecutively recruited by the Belgian Diabetes Registry. Sera obtained at clinically diagnosed onset (i.e., before start of insulin therapy or within 7 days of initial treatment) were analyzed for total IgM concentrations and for IgM binding to fixed rat splenocytes (IgM-LyAb) and permeabilized rat islet cells (IgM-ICAb). Comparison of results with those in age- and sex-matched control subjects, by fluorescence-activated cell-sorter analysis, indicated greater concentrations of IgM-LyAb and IgM-ICAb in sera from the patients. IgM antibodies reacted indiscriminately with islet beta and islet endocrine non-beta cells. The prevalence of IgM-ICAb, but not of IgM-LyAB, was significantly (P less than 0.05) higher in patients than in the control subjects. Of the ICAb-positive patients, 54% were also LyAb-positive, whereas none of the control subjects were doubly positive. IgM-ICAb and IgM-LyAb binding signals were positively correlated. Serum IgM concentrations were significantly (P less than 0.001) greater in patients than in control subjects and were significantly correlated with IgM-LyAb (P less than 0.001) and IgM-ICAb (P less than 0.01). The positivity for IgM binding was not, however, merely a reflection of total IgM, because no such correlation was found in sera from seven patients with Waldenström macroglobulinemia. Clinical onset of type 1 diabetes is apparently accompanied by increased production of IgM. The correlation between IgM concentrations and IgM binding to islet cells might reflect polyclonal activation or natural autoantibodies.
Decraene
T
T
Department of Metabolism and Endocrinology, Vrije Universiteit Brussel, Belgium.
Vandewalle
C
C
Pipeleers
D
D
Gorus
F K
FK
D000293:Adolescent; D000328:Adult; D000818:Animals; D001323:Autoantibodies / Q000276:immunology; D002097:C-Reactive Protein / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology*; D007515:Islets of Langerhans / Q000166:cytology / Q000276:immunology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013154:Spleen / Q000166:cytology / Q000276:immunology*
D001323:Autoantibodies; D007075:Immunoglobulin M; D002097:C-Reactive Protein