Anti-beta-lactoglobulin antibodies in newly diagnosed children with IDDM and their siblings

Amamentação ao seio, amamentação com leite de vaca e o diabetes mellitus tipo 1: examinando as evidências

A etiologia do diabetes mellitus tipo 1 (DM1) envolve tanto herança genética como a exposição a fatores ambientais. Evidências de estudos epidemiológicos e experimentais sugerem que a dieta pode ser importante na etiopatogenia dessa doença. Em 1984, Borch-Johnsen e col. sugeriram, com base nos resultados de um estudo caso-controle, que o leite materno seria um fator de proteção para o DM1; esse efeito se daria devido às propriedades anti-infecciosas desse tipo de leite, ou pelo fato de que a amamentação ao seio evitaria que as crianças pudessem ser precocemente expostas a outros agentes etiológicos contidos nos substitutos do leite materno. Esses mesmos achados foram poste-riormente encontrados em diversos estudos, mas o papel do leite materno no aparecimento do DM1 ainda permanece controverso. Em 1992, Karjalainen e col., ao compararem os soros de indivíduos com e sem DM1, observaram, entre os diabéticos, altas concentrações de anticorpos anti-albumina bovina. Os autores postularam a hipótese de que a albumina bovina poderia atuar como desencadeadora do processo destrutivo das células ß do pâncreas e, conseqüentemente, do diabetes. Resultados conflitantes foram observados nas publicações que se sucederam a essa. Neste artigo, resumem-se e discutem-se os achados de diferentes pesquisadores que investigaram a importância desses fatores dietéticos para o aparecimento do DM1.

Anticardiolipin antibodies in first-degree relatives of type 1, insulin-dependent, diabetic patients

First-degree relatives (FDRs) of diabetic patients are at risk of IDDM, and frequently present several autoantibodies. We detected anticardiolipin antibodies (aCL) in 42 FDRs, aged 12.4 +/- 4.2 years and in 52 controls. aCL (IgG and IgM) were measured by ELISA and their results expressed in arbitrary units. All FDRs underwent islet cell antibodies (ICA) measurement, intravenous glucose tolerance test and HbA1c levels. HLA typing and HLA-DQ molecular analysis were performed in all FDRs. Positive levels of aCL-IgG were observed in 8/42 FDRs and no control subject (p = 0.04); aCL-IgM values were similar in FDRs and controls. No correlation was found between aCL levels and chronologic age or HbA1c levels. No association was observed between aCL frequency and immunologic (ICA), metabolic or genetic (HLA) parameters. No FDR showed any feature of antiphospholipid syndrome. aCL-IgG presence in FDRs is suggestive of a need to carry out a follow-up study to establish the significance of these antibodies.

Relation between antibodies to islet cell antigens, other autoantigens and cow's milk proteins in diabetic children and unaffected siblings at the clinical manifestation of IDDM. The Childhood Diabetes in Finland Study Group

The relation between islet cell specific antibodies, other autoantibodies and antibodies to cow's milk proteins was studied in IDDM and pre-IDDM by analysing islet cell antibodies (ICA), insulin autoantibodies (IAA), anti-nuclear (ANA), anti-reticulin class IgA [ARA(IgA)], smooth muscle, anti-mitochondria, parietal cell (PCA), adrenal and thyroid antibodies and antibodies to cow's milk formula (CMF), beta-lactoglobulin (BLG) and bovine serum albumin (BSA) in a population based study with more than 650 children with newly diagnosed IDDM and more than 550 initially non-diabetic siblings. After adjustment for age a weak association was seen in the diabetic children between IAA and ANA but none between ICA and autoantibodies directed against the other organ-specific or non-organ-specific antigens. There was no significant difference in cow's milk antibodies between diabetic children with and without ICA or IAA. The siblings with ICA had higher CMF (IgA and IgM) antibody levels and BLG (IgA) antibody levels than the remaining siblings, but no such differences were found when comparing IAA-positive and negative siblings. Siblings positive for ICA had PCA more often than did the ICA-negative siblings, whereas siblings positive for both ICA and PCA had increased levels of antibodies against CMF, BLG and BSA. These findings indicate that the humoral islet cell-associated autoimmunity characteristic of recent-onset childhood IDDM is clearly restricted to the islet cells and not directly related to signs of other organ-specific or non-organ-specific autoimmunity. The observation of increased levels of antibodies to cow's milk proteins in siblings positive for ICA suggests that the immune response to cow's milk proteins may be related to the progressive autoimmune process resulting in beta-cell destruction and ultimately in the clinical manifestation of IDDM. Gastrointestinal autoimmune mechanisms may play a role in the pathogenesis of IDDM, and the association observed between combined ICA and PCA positivity and increased levels of antibodies to cow's milk proteins in the siblings implies that there may be an enhanced transfer of nutritional antigens across the gut barrier in these subjects.