Various milk antibody products produced from immune and normal colostrums have been previously tested as food supplements for the treatment of infectious diarrhea in newborn farm animals, human infants, and patients with AIDS (see reveiw ). Based on our previous obsevations that milk antibodies may prevent the overgrowth of pathogenic bacteria and subsequently reduce the bacteria toxin production, we have studied the effect of milk antibodies on the disease activity in patients with RA. In the present study, we found that milk antibody treatment was associated with clinical improvement in 10 out of 18 patients with RA, which was uncontrollable by current therapeutics due to drug resistance, complications and risk factors. In the responder group, CRP and ESR values were significantly decreased and remained at low levels during and even 1 month after the termination of treatment, suggesting perhaps a disease modifying rather than placebo effect. More importantly, use of natural antibodies was associated with alleviation of GI disorders in most of the cases, 11 of 14 patients with GI disorders in the test group. Especially, all 7 of 7 responders with GI disorder displayed the improvment of GI disorders, which was associated with improvement of arthritis and biological markers such as CRP and ESR. However, in non-responder group, no apparent improvement of arthritis symptom was observed in 3 patients regardless of improvement of GI disorders, indicating that other internal or external factors may be involved in the pathogenesis of RA or simply the dose of milk antibodies (240 mg as immunoglobulin) used in this study was not sufficient.
Since most of the patients enrolled in this study were elderly (60 ± 15 years old), it is likely that their intestinal bacteria flora balance was subject to overgrowth of certain strains of potentially pathogenic bacteria due to the lowered immune function at GALT associated with immunosenescence, which may contribute in their non-responsiveness to kefir, an immunostimulant, as shown in rats . In young adult rats, kefir enhanced immune responses to intraduodenumly inoculated cholera toxin, but kefir was not effective in elderly rats. Based on the evidence that the majority of patients suffering from gastrointestinal disorders and related diseases are elderly, milk antibodies which directly affect the intestinal bacteria is considered to be more superior than kefir. This speculation is supported by our previous studies on the effect of milk antibody treatment on intestinal bacteria flora in 47 elderly volunteers, which clearly showed that milk antibody treatment significantly reduced the population of E. Coli, Clostridium perfringens, Clostridium difficile, Clostridium subcluster XIVa OTU369 and Bacteroides OTU853, whereas it increased the population of Lactobacillus, Bacterides fragilis, genera of Bacteroides and Prevotella, Clostridium subcluster XIVa OTU995, Bacteroides OTU366, and an unidentified species of OTU443 (Iwatsuki et al, submitted). Importantly, it has been suggested that bovine immunoglobulins were partially resistant to proteolytic digestion in the human stomach and small intestine . Indeed, approximately 800 μg (0.24%) of 320 mg of bovine immunoglobulin was recovered in feces from these volunteers. These observations coincide and are in agreement with previous observations that vegetarian diet altered the intestinal bacterial flora in patients with RA [18, 19] and the change in bacteria flora could affect the outcome of disease activity.
It has been reported that translocation of bacterial cells, cell components and toxins is increased by cold , heat , psychological stress , non-steroidal anti-inflammatory drugs , surgery  and constipation . Khalif et al. reported that E. coli and S. aureus population in the feces increased in patients with chronic constipation, and their mucosal permeability for heterologous proteins was increased 30-fold compared to normal values. As a consequence, serum antibody levels to E. coli and S. aureus were significantly increased in these patients . Via such mechanisms, milk antibodies may indirectly reduce translocation of bacterial toxins  and pathogen-associated moleculules with pro-inflammatory and adjuvant effects , which might affect the disease activity in RA.
In this study, we found that pre-clinical serum IgA and IgG antibody levels to E. coli LPS (IgA: P < 0.05, IgG: P = 0.052) and IgG anti-bovine type II collagen antibodies (P < 0.09) were higher or tended to be higher in the responders than the non-responders, indicating that responders might have higher mucosal permeability as suggested by Khalif et al . In this aspect, it will be important to notice the reports showing that some patients with RA were sensitized by enterobacterial common antigens (35 and 38 kDa outer membrane protein) , and degradation products of bacterial cell walls and nucleic acids were found in RA joints .
These phenomena might be linked to genetic backgrounds as we observed in this study that there was an association between DR 15 negativity and responsiveness to milk antibodies. HLA DR15 positive patients who did not respond to the milk antibody intervention had low antibody titer to both LPS and type II collagen. Although it is not clear how DR15 contributes to the non-responsiveness to milk antibody treatment, there are potentially 2 subtypes of RA depending on an interaction between gastrointestinal pathogens and MHC class II haplotypes. It is possible that environmental factors are involved in the ethiopathogenesis of autoimmune diseases, and toll-like receptors (TLRs) that recognize molecular patterns displayed by microorganisms including LPS may play a key role in activation of the innate and adaptive immune systems .