IgA bovine serum albumin antibodies are increased in newly diagnosed patients with insulin-dependent diabetes mellitus, but the increase is not an independent risk factor for diabetes

IgG antibodies against bovine serum albumin in humans--their prevalence and response to exposure to bovine serum albumin

Human exposure to bovine serum albumin (BSA) is very common and occurs through dietary and medicinal routes. Although great effort has been made to reduce exposure to BSA in pharmaceuticals to eliminate the threat of bovine spongiform encephalopathy, less attention has been given to assessing the human immune response after exposure to BSA. A sensitive quantitative radioimmunoassay was therefore developed to measure anti-BSA IgG antibodies in healthy subjects and in cancer patients participating in a randomized, placebo controlled clinical trial where they were exposed to BSA as an intrathoracic surgical sealant during pneumonectomy. Anti-BSA antibodies were detected in 55% of 60 healthy blood donors and 51% of 83 patients before lung cancer resection. The median antibody levels were the same in both cohorts; 0.086 microg/mL (range 0.016-19.5 microg/mL) for health blood donors and 0.062 microg/mL (range 0.009-44 microg/mL) for cancer patients. Six months after exposure of the cancer patients to BSA, the percentage of patients with anti-BSA antibody rose to 96% and the median antibody level rose to 19 microg/mL (range 0.009-258 microg/mL). Placebo-treated cancer patients showed no significant increase in the percentage of patients with anti-BSA antibody (41%) or the median antibody level (0.047 microg/mL; range 0.008-1.58) over 6 months. Western blot analysis confirmed the presence of anti-BSA antibody. Elevated levels of anti-BSA antibody were not associated with any detectable clinical events in either the healthy blood donors or the cancer patients.

Antibodies to food antigens in Japanese patients with type 1 diabetes mellitus

To examine humoral and mucosal immune responses to food antigens and their relation to the pathophysiology of type 1 diabetes mellitus, IgA and IgG antibodies to cow's milk antigens (bovine serum albumin (BSA) and beta-lactoglobulin (BLG)) and another food antigen (ovalbumin, (OVA)) in human serum were assessed by enzyme-linked immunosorbent assay (ELISA). If anti-idiotype antibodies to the antibodies were present in serum, they might interfere with the ELISA assay, so suitable microtiter plates were employed to minimize such interference. The levels of IgA and IgG antibodies to the above antigens (P<0.001-P<0.01) and the prevalence of positive sera (P<0.001-P<0.05) in the patient group (n=52, aged 14.5+/-4.1 (S.D.) years) were significantly higher than those in the control group (n=41, aged 13.3+/-6.8 (S.D.) years). Interestingly, the levels of IgA antibodies to all the food antigens examined were elevated in 26 (50%) patients, while the elevation was seen in 3 (7%) healthy controls. The elevation of IgA antibodies in the patients was well correlated with increased concentrations of IgA and transforming growth factor (TGF)-beta, which induces IgA-producing B-cells, in serum. Although the cytokine TGF-beta is secreted from regulatory T-cells (Th3), and is related to oral tolerance, the interleukin-2 (IL-2, Th1)/IL-4 (Th2) ratio in the patient group was significantly elevated (P<0.001), which might indicate that the oral tolerance is impaired in patients. Thus, we demonstrated that both IgA and IgG antibodies to several food antigens are elevated in patients. We suggest that impairment of oral tolerance might be related to the pathogenesis of type 1 diabetes mellitus.

Milk and diabetes

Type 1 diabetes is based on autoimmunity, and its development is in part determined by environmental factors. Among those, milk intake is discussed as playing a pathogenic role. Geographical and temporal relations between type 1 diabetes prevalence and cow's milk consumption have been found in ecological studies. Several case-control studies found a negative correlation between frequency and/or duration of breast-feeding and diabetes, but this was not confirmed by all authors. T-cell and humoral responses related to cow's milk proteins were suggested to trigger diabetes. The different findings of studies in animals and humans as well as the potential underlying mechanisms with regard to single milk proteins (bovine serum albumin, beta-lactoglobulin, casein) are discussed in this review. In contrast to type 1 diabetes, the etiology of type 2 diabetes, characterized by insulin resistance is still unclear. In a population with a high prevalence of type 2 diabetes, the Pima Indians, people who were exclusively breastfed had significantly lower rates of type 2 diabetes than those who were exclusively bottlefed. Studies in lactovegetarians imply that consumption of low fat dairy products is associated with lower incidence and mortality of diabetes and lower blood pressures. In contrast, preference for a diet high in animal fat could be a pathogenic factor, and milk and high fat dairy products contribute considerably to dietary fat intake. Concerning milk fat composition, the opposite effects of various fatty acids (saturated fatty acids, trans-fatty acids, conjugated linoleic acid) in vitro, in animals and in humans have to be considered.

The ABBOS-peptide from bovine serum albumin causes an IFN-gamma and IL-4 mRNA response in lymphocytes from children with recent onset of type 1 diabetes

The ABBOS-peptide from bovine serum albumin (BSA) in cow's milk has been suggested to initiate the autoimmune process against the beta-cells leading to type 1 diabetes. The aim of this study was to elucidate if the ABBOS-peptide is a possible trigger of type I diabetes. The cytokines IL-4 and IFN-gamma were determined at the level of transcription as mRNA in lymphocytes, stimulated with the ABBOS-peptide. Sixteen children with newly diagnosed type 1 diabetes were compared with 10 healthy controls matched for the diabetes associated HLA-type DR3/4. Antibodies to bovine serum albumin (BSA), insulin antibodies (IA), and antibodies against islet cells (ICA) were determined, as well as serum C-peptide. Increased mRNA expression for IFN-gamma and/or IL-4 could be observed in lymphocytes from 13/16 children with recent onset of diabetes after in vitro stimulation with the ABBOS-peptide. Low expression of IFN-gamma mRNA was associated with high secretion of C-peptide, whereas a positive relationship could be observed between expression of IL-4 mRNA and insulin antibodies. Expression of IFN-gamma and/or IL-4 mRNA was also detected in lymphocytes from 6/10 healthy controls. ABBOS may have a role as a reactive epitope in the upregulation of the autoimmune process against the beta-cells but ABBOS does not seem to cause any specific Th1 response. An increased mRNA expression could also be seen in lymphocytes from healthy controls. Thus, the ABBOS-peptide might just cause or reflect an unspecific immune activity.