B lymphocytes in inflammatory airway diseases.

B lymphocytes are key players in all facets of adaptive immune responses and are responsible for the production of IgE antibodies, initiators of allergic hypersensitivity reactions. Recent evidence indicates that B cells may be a crucial player in allergic and inflammatory airway pathology, directly populating upper and lower airway tissues. This review examines human and animal studies that directly demonstrated the presence of B lymphocytes in airway tissues and elaborates on their function as antibody-secreting cells, antigen-presenting cells and producers of inflammatory and regulatory cytokines. B lymphocytes appear to contribute to multiple facets of immune homeostasis in inflammatory diseases of the upper and lower airways.

Auto-antibodies to the asialoglycoprotein receptor in sera of children with auto-immune hepatitis.

UNLABELLED: Most studies on the prevalence of asialoglycoprotein antibodies have involved adults. In this study the prevalence of antibodies to the human asialoglycoprotein receptor (ASGP-R) was determined in 63 children with auto-immune hepatitis. It was shown that 75% of those with auto-immune hepatitis type 1 and 40% of those with auto-immune hepatitis type 2 were positive and the presence of anti-ASGP-R auto-antibodies, at a mean titre of 1:1,600 and 1:1,000 respectively. No statistical significance was found between anti-ASGP-R positive and negative patients with respect to the median age at onset, proportion of females and ALT levels. However, the titre of anti-ASGP-R antibodies correlated significantly with hypergammaglobulinaemia. CONCLUSION: Anti-asialoglycoprotein receptor antibodies are frequently present in the sera of children with auto-immune hepatitis, particularly type 1, The presence of these antibodies is an indirect marker of inflammatory activity.

Formiminotransferase cyclodeaminase is an organ-specific autoantigen recognized by sera of patients with autoimmune hepatitis.

BACKGROUND & AIMS: Anti-liver cytosol type 1 autoantibodies have been reported in association with anti-liver-kidney microsome type 1 autoantibodies in 30% of patients with autoimmune hepatitis type II. In 10% of cases, anti-liver cytosol type 1 antibodies are the only liver-related circulating autoantibodies. The liver cytosol antigen is a liver-specific 62-kilodalton protein present in the cell as an oligomer of approximately 240 kilodaltons. The aim of this study was to identify the antigen recognized by anti-liver cytosol antibody. METHODS: To identify the liver cytosol antigen, an anti-liver cytosol type 1-positive serum was used for the screening of a complementary DNA library from HepG2 cells. Double immunodiffusion method was used to show the identity between the cytosolic and the cloned protein. RESULTS: The sequence of two isolated clones showed 85.2% homology with the formiminotransferase cyclodeaminase (FTCD) enzyme from pig liver. Antibodies purified by affinity with the recombinant protein and sera from mice immunized with FTCD recognized a 62-kilodalton human cytosolic protein when tested by immunoblot. The identity of precipitation lines was found between the cytosolic antigen and FTCD. CONCLUSIONS: This enzyme is a liver-specific antigen recognized by the sera of patients with autoimmune hepatitis.

Study of antigenic sites on the asialoglycoprotein receptor recognized by autoantibodies.

The aim of this study was to identify the epitopes recognized by antibodies to the asialoglycoprotein receptor, a specific hepatocyte protein, from sera of patients with autoimmune hepatitis. An ELISA test was used to detect anti-asialoglycoprotein receptor antibodies in the sera of patients with autoimmune hepatitis. Positive sera were tested against the same antigen by slot blot, by Western blot and by immunoprecipitation of the untreated protein and following treatment with beta-mercaptoethanol (beta-ME) and endoglycosidase F. The mature, unglycosylated and partially glycosylated forms of the asialoglycoprotein receptor synthesized by HepG2 cells were tested against positive patients' sera, as well as the in vitro translated unglycosylated form of the H1 subunit of the receptor. Sera from patients with autoimmune hepatitis recognized equally the native form, as well as the beta-ME-modified form, but less well the deglycosylated form of the human mature receptor. No reactivity was found when these sera were tested against the denatured human protein. In addition, neither the unglycosylated H1 subunit nor any of the HepG2-synthesized asialoglycoprotein receptor forms bound to the antibodies. Altogether, these results show that anti-asialoglycoprotein receptor antibodies in the sera of patients with autoimmune hepatitis are directed against conformational structures of the mature hetero-oligomeric form of the human liver protein and that at least some epitopes were located on the extracellular domain of the antigen.

Conformational epitopes on CYP2D6 are recognized by liver/kidney microsomal antibodies.

BACKGROUND/AIMS: Four linear antigenic sites have been shown on the CYP2D6 molecule that are recognized by serum positive for liver/kidney microsomal antibody (LKM) type 1. The aim of this study was to search for antibodies against CYP2D6 conformational antigenic sites in LKM-1-positive sera. METHODS: The capacity of four LKM-1-positive sera, before and after absorption with synthetic peptides representing CYP2D6 linear antigenic sites, and rabbit sera against linear antigenic sites between CYP2D6 amino acids 254-271 and 373-389 to inhibit the O-demethylation of dextromethorphan by CYP2D6 was tested in vitro. RESULTS: Inhibition of O-demethylation of dextromethorphan was not modified by absorption of antibodies against linear CYP2D6 antigenic sites. In addition, rabbit sera against two of these sites did not inhibit the reaction. These results strongly suggest that antibodies against CYP2D6 conformational antigenic sites were present in LKM-1-positive sera. CONCLUSIONS: The autoimmune response against CYP2D6 is directed against linear and conformational antigenic sites. These results strengthen the argument that the LKM-1 response is polyclonal and antigen driven.

Immunotoxicity of subchronic versus chronic exposure to aldicarb in mice.

In this study we compared the immunotoxicity of subchronic vs chronic exposure to the aldicarb insecticide at a relatively low, 0.1-10 ppb, level in drinking water. The immunotoxicity of aldicarb was evaluated in 28- and 90-day studies by determination of the humoral, cellular and nonspecific immunity in inbred C57BL/6 mice. Quantification of splenic plaque-forming cells (PFC) to sheep erythrocytes (SRBC), mitogen activation of spleen lymphocytes, mixed lymphocyte reaction (MLR) and the cytofluorometric assay of the phagocytic uptake of fluorescent beads were among the parameters studied. Neither the cell viability nor the splenic cell count was affected by the insecticide exposure. Immunophenotyping and cytometric determination of L3T4+, Lyt2+ and Ig+ cells revealed no effect of the insecticide exposure on the total count of cell subsets in the ungated splenocyte population. However, a marked shift in the percentages of L3T4+ and Lyt2+ cells was noted after subchronic exposure to 1 and 10 ppb aldicarb, possibly indicating activation of these splenic T-cell subsets. Subchronic aldicarb exposure significantly suppressed the splenic PFC response to SRBC at 1 ppb dose, however, no dose-effect correlation could be concluded. Similarly, no dose-effect correlation was observed for subchronic aldicarb-related changes in mitogen responses. Subchronic exposure to aldicarb had no statistically significant effect on the mixed lymphocyte reaction (MLR) or on the macrophage phagocytosis. Chronic exposure to 0.1-10 ppb aldicarb did not affect any of the parameters measured, including the cell subsets. Thus, aldicarb-related changes in immune parameters, noted after a 28-day exposure, were compensated over chronic exposure to the insecticide.