Effect of anti-immunoglobulin antibodies provides new insights into immune response to HCV

Measurement of IgG levels can serve as a biomarker in newly diagnosed diabetic children

This study was undertaken to determine humoral immune response to the presence of anti-immunoglobulin antibodies in children with newly diagnosed type 1 diabetes mellitus, using as a target cow immunoglobulins, in an attempt to elucidate further complex immuno-pathogenetic interactions of the disease. Serum immunoglobulin G (IgG) concentrations were measured by ELISA in 30 children with type 1 diabetes mellitus and 30 healthy matched normal children. It was found that normal children had a mean IgG level of 7.41 mg/ml while diabetic individuals had a mean IgG level of 8.52 mg/ml (p<0.00004). On the contrary, the mean level of IgG in diabetic sera after purification from anti-cow immunoglobulins was determined to be 7.52 mg/ml. Therefore, there was no significant difference in IgG level in patients with type 1 diabetes mellitus after removal of anti-cow immunoglobulin antibodies compared to normal children (p<0.58). Visualization of IgG and immuno-precipitation confirm that anti-cow immunoglobulins antibodies, which were unrelated to antigen, were co-precipitated with the antigen-antibody complex. A circulating immunoglobulin reacting with other immunoglobulins is thus present in children with type 1 diabetes and may well play a part in the complex immuno-pathogenetic interactions.

M cell-targeted ocular immunization: effect on immunoglobulins in tears, feces, and serum

PURPOSE

This study investigates whether antigen-sampling M cells, present in the follicle-associated epithelium (FAE) above organized conjunctiva-associated lymphoid tissue in rabbits, bind and retro-transport secretory IgA (sIgA) from the tear film. The hypothesis that IgA-mediated uptake of antigens promotes local and systemic production of immunoglobulins was tested.

METHODS

sIgA binding and retro-translocation by M cells was characterized by immunocytochemistry. Immunoglobulin concentrations in tears, feces and serum were measured using enzyme-linked immunoassays (ELISA) after topical and systemic immunization with either goat IgG anti-rabbit IgA or nonspecific goat IgG.

RESULTS

Endogenous sIgA was found associated with the apical membrane of conjunctival M cells. Exogenous anti-IgA immunoglobulins were translocated across M cells. Significant levels of sIgA against goat IgG were present in tears of pre-immune animals. Topical application of either goat IgG specific for rabbit IgA or nonspecific goat IgG led to similar increases in antigen-specific IgA in tear, feces, and serum. The antigen-specific IgG response in tears mirrored the serum response for both immunogens consistent with transudation of this immunoglobulin. The IgM response in tears and serum was weak for both immunogens. Systemic immunization did not sustain or enhance the local mucosal IgA responses.

CONCLUSIONS

Conjunctival M cells bind and translocate sIgA from the tear film. Topical conjunctival immunization leads to generation of antigen-specific immunoglobulins from both local and distant mucosae and in serum. Natural antibodies, present in the tear film before immunization, may have contributed to similar immune responses to goat anti-rabbit IgA and nonspecific goat IgG.