Secretory immunoglobulin deposits in renal glomeruli of children with extrahepatic biliary atresia: studies in a human counterpart of experimental ligation of the bile ducts

Experimental ligation of the biliary tract often results in glomerular deposits of polymeric IgA commonly associated with secretory component. These studies offer evidence that, in animals, hepatobiliary transport of polymeric IgA, which is of mucosal origin, is crucial for its clearance from the serum. We studied a human counterpart of bile duct ligation--extrahepatic biliary atresia--for the presence of secretory or polymeric immunoglobulins in renal glomeruli. Kidney was available at autopsy as paraffin or frozen blocks from 24 patients with biliary atresia and age-matched controls (5 weeks to 5 years old). Several of the patients had undergone portoenterostomy (Kasai procedure) or liver transplantation. Immunohistologic studies showed glomerular (often mesangial) deposits of IgA in 10 of 24 and IgM in 16 of 24 specimens. The differences with controls were highly significant for IgA but not for IgM. In frozen sections, secretory component was positive in glomeruli in seven of 12 specimens. In vitro glomerular binding of purified secretory component to glomeruli was shown in four of 12 samples, including three with IgM only. This last observation suggests that IgM in some of these patients was polymeric and thus derived from a mucosal source. Our study shows that in humans with biliary atresia, secretory IgA, polymeric IgA, and possibly polymeric IgM are deposited in glomeruli. The study confirms the occurrence of renal immunopathologic findings in liver disease and supports the existence of an active hepatobiliary immunosecretory transport mechanism even at the early age of these patients.

Early detection of liver metastasis in patients with colorectal carcinoma by increased levels of circulating IgA- and IgM-associated secretory component

One hundred patients operated for colorectal carcinoma were followed clinically and with serial blood samples from 5 to 8 years. Levels of secretory component (SC) associated with IgA and IgM in serum were measured and related to Dukes' stage, histological differentiation, tumour expression of SC, and circulating carcinoembryonic antigen (CEA). On the whole, elevated levels of SC in serum were found in 15 of the 20 patients who already had (n = 15), or later developed (n = 5), liver metastasis. Four of the latter 5 patients showed raised SC levels with a 5.5 months median lead time from the first positive serum sample to clinically manifest liver disease. These data are interesting in view of the promising results reported for liver resection in patients with colorectal carcinoma.

Heterogeneous epithelial expression of class II (HLA-DR) determinants and secretory component related to dysplasia in ulcerative colitis

The intensity and degree of heterogeneous epithelial marker expression were evaluated immunohistochemically in 29 mucosal biopsy specimens from 7 ulcerative colitis (UC) patients with dysplasia. Biopsy specimens from UC patients with mild (n = 7) or severe (n = 6) inflammation and from histologically normal samples (n = 7) served as controls. HLA-DR showed heterogeneous epithelial expression in all lesions with high grade dysplasia and in 6 of 8 with low grade dysplasia. SC was heterogeneous stained in 17 of 21 lesions with high grade dysplasia and in all but two lesions with low grade dysplasia. In histologically normal mucosa, SC was homogeneously expressed and epithelial DR was virtually absent. In mildly inflamed UC lesions, SC exhibited patchy distribution in only one sample and DR in two, whereas both SC and DR showed a slight degree of heterogeneous expression in all lesions with severe inflammation. Moreover, the overall intensity of SC staining tended to decrease with increasing degree of inflammation, whereas the opposite was seen for DR. Decreased SC and increased DR expression thus seemed to be related to intensified inflammatory activity, whereas heterogeneous expression of these markers was significantly more related to dysplasia.

Enzymatic and antigenic characterization of immunoglobulin A1 proteases from Bacteroides and Capnocytophaga spp

Bacteroides and Capnocytophaga species have been implicated as periodontal pathogens. Some of these species possess immunoglobulin A1 (IgA1) proteases that are capable of cleaving the human IgA1 molecule in the hinge region, leaving intact Fc alpha and Fab alpha fragments. The purpose of this study was to characterize this activity. In addition to IgA1 protease activity in already known species, IgA1 protease activity was a feature of Bacteroides buccalis, Bacteroides oralis, Bacteroides veroralis, Bacteroides capillus, and Bacteroides pentosaceus. Results of immunoelectrophoretic and sodium dodecyl sulfate-polyacrylamide gel electrophoretic analyses suggested that all species cleave the alpha-chain at the same peptide bond, i.e., the prolyl-seryl bond between residues 223 and 224 in the hinge region. The Bacteroides proteases could be classified as thiol proteases, which were at the same time dependent on metal ions, while the Capnocytophaga proteases were metallo enzymes. None of the proteases were inhibited by the physiologic proteases inhibitors alpha 2-macroglobulin and alpha 1-proteinase inhibitor. Investigations with enzyme-neutralizing antibodies raised in rabbits against protease preparations from the respective type strains revealed that, despite otherwise identical characteristics, the IgA1 protease of each Bacteroides species was antigenically distinct. Bacteroides buccae and the two later synonymous species B. capillus and B. pentosaceus produced identical proteases. In contrast, IgA1 proteases from Capnocytophaga ochracea and Capnocytophaga sputigena strains were apparently identical, while Capnocytophaga gingivalis had a protease that differed from those of the other Capnocytophaga species.

Hormonal influence on the secretory immune system of the eye: endocrine interactions in the control of IgA and secretory component levels in tears of rats

Previous research from our laboratory has demonstrated that androgens regulate the ocular secretory immune system of the rat. The purpose of the present study was to determine whether other hormones might influence this androgen effect. Experiments involved the daily administration of saline or hormones to adult orchiectomized rats, the collection of tears 24 hr after the fourth hormone injection, and the measurement of free secretory component (SC), IgA and total protein levels in tears. Our first aim was to evaluate whether female sex steroids might antagonize androgen action on tear IgA and SC: orchiectomized rats were treated with combinations of saline, testosterone, oestradiol or progesterone. Testosterone induced a significant increase in the tear SC and IgA concentrations, as compared to those of saline-injected controls. This androgen effect was not inhibited by co-treatment with oestradiol or progesterone, nor duplicated by the administration of these hormones alone. Our second aim was to assess whether the absence of certain hormones might alter tear SC and IgA levels, or influence the ocular response to androgen exposure: rats underwent orchiectomies and specific endocrine organ ablations or appropriate sham-surgery. Absence of the pituitary gland, but not the thyroid, adrenal or pineal glands, resulted in a significant decrease in tear SC, IgA and total protein content. In addition, removal of the thyroid or adrenal glands did not prevent the testosterone-associated increase in tear SC and IgA, although thyroidectomy or adrenalectomy did diminish the magnitude of the androgen response. In contrast, hypophysectomy completely blocked the effect of testosterone on both tear SC and IgA. These results indicate that the hypothalamic-pituitary axis may regulate, or mediate, the action of androgens on ocular immunity in the rat.

High and low molecular weight rabbit secretory components. Evidence for the deletion of the second and third domains in the smaller polypeptide

Rabbit secretory components exist in two forms which differ in apparent mass by about 25 kDa. Each of these two forms were reduced, carboxymethylated, and extensively digested with trypsin. The resulting peptides were purified by reverse-phase high performance liquid chromatography and characterized by NH2- and COOH-terminal sequence determination and/or amino acid analysis. They were aligned with the protein sequence predicted from the cDNA nucleotide sequence encoding the rabbit poly(Ig) receptor (Mostov, K. E., Friedlander, M., and Blobel, G. (1984) Nature 308, 37-43). All peptides belonging to the fourth and fifth domains except one (positions 488-496) were accounted for in both forms. In addition, limited tryptic proteolysis of the native low Mr secretory components produced the intact 18-kDa NH2-terminal domain (positions 1-117) and the 30-kDa fragment encompassing the fourth and fifth domains. These results suggest that the smaller polypeptide derives from the larger secretory component form by the deletion of the second and third domains.

Analysis of the mechanism, rate, and sites of proteolytic cleavage of human immunoglobulin D by high-pressure liquid chromatography

The high susceptibility of human immunoglobulin D to proteolytic degradation affects its biological function, metabolism, and immunoassay. High-pressure liquid chromatography was used to investigate the mechanism and rate of limited proteolytic cleavage of IgD and also to identify, isolate, and quantify the reaction products. Within 1 to 5 min, tryptic digestion of native IgD almost quantitatively yields a labile Fab fragment, a stable Fc fragment, and a highly charged peptide derived from the hinge region. A galactosamine-rich glycopeptide from the hinge region increases inversely as the Fab is largely degraded to a series of peptides within 1 hr. In contrast, the Fc and the high-charge peptide resist proteolysis for more than 24 hr. The initial sites of cleavage of IgD occur in the hinge region at exposed secondary structures predicted to be beta-turns. Concomitant with removal of the galactosamine-rich glycopeptide at its carboxyl terminus, the Fd fragment is rapidly and rather randomly degraded, but the light chain is somewhat more resistant than the Fd section of the delta heavy chain. This study of the rapid rate of proteolysis of IgD explains the rarity with which intact IgD is found in human sera. It also raises questions about immunoassay of IgD, which is usually measured with antisera against Fc. In vivo, proteolytic cleavage initiates the catabolism of circulating IgD and also affects the role and fate of IgD as an antigen receptor on the B-cell membrane.

Secretory immune responses in human kidneys

The secretory immune system has been well studied in the intestinal, bronchial, and biliary systems and breast. Tissue studies of secretory immunoglobulins in the kidney are scanty, mostly related to nephropathies with IgA. Renal tissues from 37 autopsies selected for any history of renal dysfunction were processed for immunohistologic studies on frozen sections with several antisera, including a purified rabbit anti-human secretory component (SC). By immunohistology, gel diffusion, and immunoblotting, the anti-SC antibody reacted appropriately with purified human SC, saliva, intestinal epithelium, and breast milk and did not cross-react with immunoglobulin heavy or light chains, lactoferrin, and other tissue proteins. IgA and SC were seen in tubular casts in 70% of patients, whereas less impressive staining with IgM, IgG, and albumin was seen, respectively, in 24%, 13%, and 22% of the patients. SC was present in the cytoplasm of distal tubule and Henle's loop cells in 78% of specimens. A control group of 10 healthy individuals who died suddenly showed minimal staining of casts and tubules in 2 specimens. Renal pathology in the group with IgA-SC+ casts included acute tubular necrosis (54%), severe chronic renal disease (61%), and mild chronic renal injury (38%). The group with negative IgA-SC casts included acute tubular necrosis (64%), infectious interstitial nephritis (36%), and negligible renal disease (36%). This study suggests that discrete distal segments of the nephron may have the capability of secreting SC, which is probably coupled with serum-derived IgA and incorporated into luminal tubular secretions. The low level of immunosecretions in kidneys which are normal or minimally damaged suggests that this system may need to be turned on by unknown, probably pathogenic stimulating factors.

Secretory component in pulmonary adenocarcinoma and mesothelioma

The distribution of secretory component was examined by an immunoperoxidase method in 40 pulmonary adenocarcinomas, 11 malignant pleural mesotheliomas and areas of normal lung adjacent to the tumours. Secretory component was demonstrated in tumour cells in 25 (67%) adenocarcinomas. Its presence correlated with the degree of differentiation but was not related to tumour pattern. In the normal lung secretory component can be demonstrated in bronchial ciliated cells, bronchial gland serous cells, bronchiolar epithelium and hyperplastic alveolar epithelium. Although not usually detectable in normal mucous cells it was frequently present in mucin-producing tumours. None of the mesotheliomas examined contained secretory component and this may be an additional useful feature in the differential diagnosis between mesothelioma and adenocarcinoma.

Immunohistochemical distribution of immunoglobulin and secretory component in the ileum of normal and paratuberculosis-infected cattle

The immunohistochemical distribution of IgA, IgG, IgM and secretory component in the ileum of 10 normal and 21 paratuberculosis-infected cattle was investigated. Semi-quantitative analysis of the number of each class of Ig-containing cells in the lamina propria mucosa of infected ileums showed that IgG and IgM-containing cells and total Ig-containing cells were significantly more numerous than those in the normal ileums. There was no significant difference in the numbers of IgA-containing cells between the two groups of cattle. The distribution of IgA, IgM and SC was basically similar in the two groups. However, IgG-containing cells characteristically accumulated around the granulomas. It was considered that excessive local production of Ig in the intestinal mucosa, along with subsequent formation of immune complex or release of histamine from mast cells, could account for the occurrence of diarrhoea and participate in the pathogenesis of bovine paratuberculosis. A comparison of the local immunological state in paratuberculosis and Crohn's disease was made.

The proteolytic activity of milk fat, whey and casein for iodinated, extrinsic bovine IgG1, IgG2, SIgA and IgM

Purified, iodinated bovine immunoglobulins (Igs) were incubated with fresh Guernsey milk or with the casein, fat and whey fraction of such milk for up to 12 hr at 37 degrees C. Igs incubated in whole milk, showed little evidence of proteolysis in either the whey, fat or casein fractions although the amount of radioactivity which became associated with the latter two fractions prevented adequate analysis. When the individual milk fractions were first prepared and then incubated with iodinated Igs, we found no evidence for proteolysis of any Ig in whey or casein but ca. 25% breakdown or dissociation of the IgM and SIgA which had been incubated with milk fat. Breakdown of these Igs in fat was not inhibited with benzamidine-HCl, sodium azide or EDTA. These data show that: only those Igs which associate with milk fat are degraded or dissociated by it and the Ig fragments described from cows milk or recovered during studies on Ig transport cannot be ascribed to the proteolytic activity of fresh milk.

Secretory piece and IgA deficiency in a patient with Waldenstrom's macroglobulinemia

A case of a patient suffering from Waldenstrom's macroglobulinemia who developed diarrhea and mild steatorrhea is described. Laboratory studies revealed low serum IgA, intestinal secretory IgA deficiency, and small intestine bacterial overgrowth as demonstrated by the C14-cholylglycine breath test. These findings suggest that selective IgA deficiency and secretory component deficiency may be contributing factors in the development of diarrhea in Waldenstrom's macroglobulinemia.

Influence of a minor recurrent idiotype on the regulation of immune response: route dependence

Sp6, a BALB/c hybridoma, produces anti-TNP IgM antibodies (AB), which carry a minor recurrent idiotype (ID). Despite the fact that only about 20% of BALB/c anti-TNP AB carry the Sp6 ID, injection of Sp6-coated spleen cells (Sp6-SC) significantly influenced the anti-TNP B cell response. Repeated intratrail (i.t.) or intravenous (i.v.) injections of Sp6-SC resulted only in a minor increase of the anti-TNP background response. When mice consecutively were challenged with TNP-horse red blood cells (HRBC), i.t. injections of Sp6-SC resulted in a 2-3-fold increase in the number of anti-TNP plaque-forming cells (PFC), while i.v. injection of Sp6-SC displayed no effect on a primary anti-TNP response. But, after i.v. as well as i.t. application of Sp6-SC, it was not possible to obtain hapten-specific suppression by i.v. injection of TNP-haptenized lymphocytes. In vitro characterization of the underlying mechanism revealed that the helper effect, which only was observed after i.t. injection, was due to a Lyt-1+ population, not adhering to Sp6-coated plates, while counterregulation of hapten-specific suppression was found in a Lyt-2+ population, adhering to Sp6-coated plates. Hence, depending on the route of priming, injection of AB with a recurrent ID can augment the response towards the nominal antigen either directly via activation of helper cells or indirectly via activation of counterregulatory cells.

Possible mechanisms of elevation of serum secretory immunoglobulin A in liver diseases

In order to investigate possible mechanisms of elevation of serum secretory immunoglobulin A (sIgA) in liver diseases, human liver specimens were applied to immunohistochemical study of immunoglobulin A, secretory component, and J chain, which are components of sIgA. In the cases of chronic hepatitis with high serum sIgA levels, these antigens were present in dilated bile canaliculi of hepatocytes and they were continuously stained on the lateral plasma membrane of hepatocytes from the bile canaliculus to the space of Disse over the junctional complexes. Furthermore, in liver cirrhosis and extrahepatic cholestasis, they were also detected in intraportal bile ductules and intercellular spaces of degenerated cholangiocytes. These results suggest that at least two pathways might allow elevation of serum sIgA: through the communication of the bile canaliculus with the space of Disse over junctional complexes and through the bile ductule into the portal blood vessel.

[Immunohistochemical localization of epithelial membrane antigen, carcinoembryonic antigen and secretory component in urinary bladder cancer]

To clarify the relationship between the immunohistochemical distribution pattern of epithelial antigens in transitional cell carcinomas and their histopathological grading and staging, epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA) and secretory component (SC) were localized. Formalin-fixed paraffin-embedded sections from 55 patients with bladder carcinoma were stained by the indirect immunoperoxidase method. In normal transitional epithelium, EMA was found on the luminal side of the plasma membrane of a few surface layers, and in the cytoplasm of the superficial cells. In the lower grade and stage of transitional cell carcinoma, only the luminal surface of superficial cells was positively stained. Membrane and cytoplasmic staining of EMA was frequently found in the intermediate and basal layers of the carcinoma, and the incidence of cytoplasmic staining increased with the higher grade and stage. CEA was not detected in normal epithelium. Cytoplasmic staining of CEA was progressively more frequent in the higher grade and stage of transitional cell carcinoma. In normal epithelium SC was observed on the apical surface plasma membrane and in the cytoplasm of the superficial cells, as shown in the immunohistochemical staining for EMA. The correlation of immunohistochemical detection of SC with the grade or stage was not as good as the correlations for EMA or CEA. These findings suggest that immunohistochemical examination for EMA, CEA and SC in bladder carcinoma could provide valuable information for grading or staging in pathological diagnosis.

[Dependence of the specific activity of antitetanus immunoglobulin on the degree of its fragmentation]

Antitetanus immunoglobulin preparations with the increasing content of Fab-fragments (15, 30, 53%) have been obtained under specific experimental conditions. Tests for specific activity have revealed an insignificant decrease (13%) in this activity in the preparation containing 15% of Fab-fragments and its sharp drop in the preparations containing 30-50% of Fab-fragments. The specific activity of antitetanus immunoglobulin has been found to be related to the degree of its fragmentation.

[Primary structure and species specificity of immunopoietins]

A model involving quasicyclization of protein molecules following the stepwise reactions of limited proteolysis was developed. On the basis of the model new active sites were detected in immunoglobulins of various species as well as chemical synthesis of the sites was carried out. The new group of the substances was designated as immunopoietins. The primary structure of various species immunoglobulins was analyzed and evolutional stability of the immunopoietin structure was shown.

Abnormal expression of secretory component in term newborns with bowel perforation--a report of two cases

Expression of secretory component (SC) in intestinal resection specimens from two term newborns with bowel perforation due to necrotizing enterocolitis (NEC) or and NEC-like syndrome was determined and compared with the SC immunoreactivity in a panel of intestinal tissues from fetuses at different ages of gestation. Expression of SC was absent in one patient, whereas in the other patient, SC immunoreactivity was observed in the basal cell part of colonic epithelium only. SC was normally expressed in a follow-up biopsy on one of these patients. In contrast, SC was present in the apical plasma membrane and brush border of colonic epithelium from 32 weeks of gestation onwards in fetuses without demonstrable intestinal disease. From these findings we conclude that the expression of SC was impaired in our patients, thus possibly playing a role in the development of the bowel perforation in these full-term newborns with an NEC-like syndrome or resulting from its pathogenesis.

Quantitative determination of platelet surface alloantigens using a monoclonal probe

A monoclonal antibody with specificity for the Fc portion of IgG was used to determine the number of IgG alloantibody molecules bound at saturation to alloantigens of the PlA1 and HLA systems on normal human platelets. In preliminary studies, it was found that the number of cell-bound IgG molecules recognized by this probe correlates well with the number measured by electroimmunoassay, an independent measure of alloantibody binding. PlA1-positive platelets could be divided into two groups binding 34,000-43,000 or 19,000-24,000 alloantibody molecules. Family studies and studies with a cytolytic assay showed that the former group is homozygous and the latter heterozygous for PlA1. Because the number of glycoprotein IIIa (GPIIIa) molecules carrying the PlA1 determinant on the surface of normal platelets is thought to be about 40,000, these findings suggest that each GPIIIa molecule carries one PlA1 determinant. The number of class I HLA molecules expressed on normal platelets was considerably smaller than the number of PlA1 determinants, ranging from 4400 to 10,000 (HLA-A2), 870 to 8400 (Bw4), and 1300 to 5800 (Bw6). Preliminary analysis indicates that stronger or weaker expression of Bw4 and of Bw6 correlates with certain "private" HLA-B determinants carried on the HLA-B molecule as found in previous studies using an indirect method to measure alloantigen density. These findings appear to explain why antibodies reactive with platelet-specific antigens such as PlA1 react more strongly with platelets than HLA-specific antibodies in most serologic tests. The weak expression of HLA determinants on platelets of some subjects may account for the less than perfect correlation between in vitro compatibility tests and post-transfusion platelet survivals observed in most studies.

Defective DNA-receptor function in systemic lupus erythematosus and related diseases: evidence for an autoantibody influencing cell physiology

The receptor for DNA was functionally defective in the majority of patients with systemic lupus erythematosus (SLE; 91% of 35 studied) and allied rheumatic disorders. This functional defect was manifest by impaired binding of exogenous DNA to the cell surface of peripheral blood mononuclear cells and an inability of cells to internalise and degrade DNA. The receptor defect was not constitutive, since it could be reversed by overnight incubation of cells; this process was sensitive to cycloheximide, suggesting a requirement for active receptor regeneration. The DNA-receptor defect could be induced in healthy controls, by incubating their cells with the serum of patients with SLE. The humoral factor inducing the defect was an autoantibody.

An enzyme-linked immunosorbent assay for differential quantitation of secretory immunoglobulins of the A and M isotypes in human serum

An enzyme-linked immunosorbent assay was developed for differential quantitation of secretory IgA (SIgA) and secretory IgM (SIgM) in human serum. The assay was based on non-competitive binding of SIgA and SIgM to microplates coated with an excess of antibodies to secretory component (SC). Appropriate standards were included to obtain absolute values. Mutual competition of SIgA and SIgM was avoided by testing the serum samples at sufficiently high dilutions. The assay is fast, simple, sensitive and reproducible. All of the 138 healthy individuals tested (1-91 years old) were found to have both SIgA and SIgM in their serum (medians, 10 mg/l and 14 mg/l, respectively). Lactating women, SIgA-deficient healthy individuals, and particularly patients with hepatitis had significantly increased serum SIgM levels compared with controls. Differential quantitation of SIgA and SIgM may turn out to be of diagnostic value and provide pathogenetic information.

Characterization of complexes containing protein A and rabbit immunoglobulin G or Fc gamma fragments

Soluble complexes prepared over a range of molar ratios of [125I] protein A (SpA) and rabbit [131I]immunoglobulin G (IgG) or [131I]Fc gamma fragments were separated by ultracentrifugation in a sucrose gradient and selectively radioimmunoprecipitated with chicken antibodies that bind free or complexed SpA. With excess [125I]SpA the only complexes formed were composed of one molecule of labeled ligand and one molecule of [125I]SpA (1:1 complexes). With excess ligand the only complexes formed corresponded to [(IgG)2SpA]2 or [(Fc gamma)2SpA]2 (4:2 complexes). The 4:2 complex likely is responsible for several of the biological activities associated with SpA, including activation of humoral and cellular immune mechanisms, which are optimal under conditions of excess IgG.

Distribution and processing of the polymeric immunoglobulin receptor in the rat hepatocyte: morphological and biochemical characterization of subcellular fractions

The transepithelial transport of polymeric immunoglobulins is an essential process in the mucosal immune system. Transport across the epithelial cells of mucous or exocrine glands is affected by an integral membrane glycoprotein receptor known as membrane secretory component (SCm) or as polymeric immunoglobulin receptor (pIgR). This receptor binds polymeric immunoglobulins at the basolateral cell surface and mediates their transcellular translocation and their release from the apical plasma membrane into external secretions. Release depends on cleavage of the membrane-anchoring domain of the receptor, resulting in liberation of polymeric immunoglobulin bound to the ectoplasmic domain of the receptor (secreted SC or SCs) into extracellular secretions. Using a monoclonal antibody directed against the cytoplasmic tail of the receptor and a polyclonal antibody directed against the secreted ectoplasmic domain, we have combined cell fractionation and Western blotting techniques to examine the fate of these receptor domains in the hepatocyte. In this study, we characterize biochemically and morphologically the various subcellular components separated by our fractionation scheme, and correlate this with biochemical analysis of the receptor in each fraction.