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D L Delacroix

Publications and source records attributed to D L Delacroix.

50 records · Page 3Linked to original sources
PubMed1982

Influence of molecular size of IgA on its immunoassay by various techniques. II. Solid-phase radioimmunoassays.

Homogeneous, polymeric (P), monoclonal (MC) and polyclonal (PC) samples of purified IgA, as well as of secretory IgA (sIgA), were compared to their corresponding monomeric (M) forms with regard to their respective behaviour in both a solid-phase double antibody (AB) immunoradiometric assay (IRMA) and a solid-phase competition radioimmunoassay (CRIA). On an identical weight basis, both assays underestimated the P forms. Correction factors (CF), i.e., optical density (OD) versus radiometric concentration ratios, were calculated for both methods for all P forms, using M as standards. IRMA CF were respectively 1.50 for dimer, 1.98 for secretory IgA and 2.40 for tetramers, very similar to those obtained in radial immunodiffusion (RID). With optimally coated beads, these CF were stable along a wide range of concentrations. In contrast, CRIA-CF were 3-4 times larger and displayed much variation along their standard range of concentrations, preventing the use of a constant CF along the standard curve. Our present IRMA, with its CF, should be of value for a more accurate quantitation of small amounts of IgA of various known sizes.

Bile↗
PubMed1982

Influence of molecular size of IgA on its immunoassay by various techniques. III. Immunonephelometry.

The influence of size heterogeneity of IgA on its immunonephelometric (IN) assay was studied using highly purified preparations of monoclonal (MC) or polyclonal (PC) monomeric (M), dimeric (D), trimeric (T) and tetrameric (Q) IgA, as well as of secretory IgA (sIgA). Concentrations measured by optical density (OD) were compared to IN--concentrations obtained by using M as standards, on an equal weight basis. No significant difference was found between OD and IN concentrations of D, T, Q and sIgA were only slightly underestimated, with correction factors (CF) of 1.16, 1.20 and 1.24, respectively. The value of 1.24 for our sIgA sample (84% of 11S, 16% of 15S) could be due to the fact that secretory component represents about 20% of the mass of the sIgA molecule. IN seems a method of choice for measuring IgA concentrations in the range of microgram/ml, almost independently of the size of IgA.

Animals↗
PubMed1982

Influence of molecular size of IgA on its immunoassay by various techniques--I. Direct and reversed single radial immunodiffusion.

Immunochemically pure samples of monoclonal and polyclonal IgA were prepared from human sera and milk. Samples of various homogeneous molecular sizes were further obtained by preparative ultracentrifugations. The different behaviour of each preparation (monomer, dimer, trimer, tetramer and secretory IgA) were studied in direct (DRID) and reversed (RRID) single radial immunodiffusion using three different anti-alpha-chain antisera and IgA samples of various monoclonal and polyclonal origins. In DRID, all polymer concentrations were underestimated when using monomers as standards, on an equal weight (OD) basis. Correction factors (CFs) were calculated from monomer to polymer DRID slope ratios. The means +/- SDs of these CFs were 1.55 +/- 0.18 for serum dimers, 1.85 +/- 0.10 for trimers, 2.63 +/- 0.26 for tetramers and 2.24 +/- 0.15 for secretory IgA (84% 11S, 16% 15S). These results were confirmed by RRID.

Antibodies, Monoclonal↗
PubMed1982

Immunoglobulins in rabbit hepatic bile: selective secretion of IgA and IgM and active plasma-to-bile transfer of polymeric IgA.

Proteins in hepatic bile from cannulated rabbits were analysed by gel filtration, electrophoresis, density gradient ultracentrifugation, and immunochemical methods. Bile-to-serum concentration ratios (no. = 8) demonstrated that IgA and free secretory component (SC) were major constituents of rabbit bile. Relative concentration ratios, obtained by dividing the bile to serum level ratio for each protein by the corresponding ratio for albumin, were 310, 1.6, 1.0, 0.82, and 0.54 for IgA, IgM, albumin, transferrin, and IgG respectively, suggesting that both IgA and IgM are selectively secreted into bile. Ligation of the bile duct (no. = 5) led to a selective increase of the serum levels of IgA and SC, the latter as secretory IgA. After intravenous injection (no. = 4) of human polymeric IgA, 37-69% of the injected dose was recovered in bile after 3 h, in contrast to 4-5% for human monomeric IgA. The active transfer of both rabbit and human polymeric IgA into rabbit bile occurs via the same hepatic SC-mediated transport process as that described for the rat.

Animals↗
PubMed1982

Selective transport of polymeric immunoglobulin A in bile. Quantitative relationships of monomeric and polymeric immunoglobulin A, immunoglobulin M, and other proteins in serum, bile, and saliva.

In 17 adults, serum, hepatic bile, and saliva samples were analyzed for their sedimentation profile of IgA and secretory component (SC), and for their concentrations of albumin, orosomucoid, transferrin, IgG, IgA, alpha 2-macroglobulin (alpha 2M), IgM, and SC. Polymeric IgA(p-IgA) averaged 13% (50-700 micrograms/ml) of total IgA in serum, 70% (43-88%) in bile, and 93% (74-98%) in saliva. Most of the p-IgA in bile sedimented with SC, which also occurred free (8-44%), and with IgM. In bile, albumin (155-1,485 micrograms/ml) was the predominant protein, followed by IgG (32-480 micrograms/ml), and total IgA (37-209 micrograms/ml). In saliva, p-IgA (72-902 micrograms/ml) predominated, followed by albumin (16-385 micrograms/ml) and IgG (9-178 micrograms/ml). Secretion-to-serum albumin-relative concentration ratios (S/S-ARCR = 1 for albumin) in bile averaged 22 for p-IgA, 1.91 for IgM, 1.28 for monomeric IgA (m-IgA), 0.70 for IgG, and 0.57 for alpha 2M, indicating for p-IgA, IgM, and to a lesser extent for m-IgA, a selective excretion into bile. In saliva, a 16-fold greater selective excretion of p-IgA (mean S/S-ARCR = 354) was found. Labeled m- and p-IgA were injected intravenously into five patients. Specific activities indicated that for p-IgA 50% was serum derived in bile, as compared with 2% in saliva, and to 85% for m-IgA in bile. In the patient with the highest excretion of 125I-p-IgA in bile, only 2.8% of the injected dose was recovered in bile within 24 h after injection. Compared with rats and rabbits, the serum-to-bile transport of p-IgA in humans is much smaller.

Bile↗
PubMed1982

Serum IgM-bound secretory component (sIgM) in liver diseases: comparative molecular state of the secretory component in serum and bile.

The sera of 15 patients with liver disease and high serum concentrations of secretory component (SC) were analyzed by density gradient ultracentrifugation and radioimmunoassays for SC, IgA, and IgM to determine the molecular state of SC and IgA. Results in serum were compared to those obtained by simultaneous analysis of bile in five of the patients, and to those in serum and bile of a case of total IgA deficiency. Free SC was virtually not found in sera, although it was well represented in all bile, up to 88 and 97% of total bile SC in a case of complete biliary obstruction and in IgA deficiency, respectively. IgM-bound SC was found in all sera, amounting to 91% and 100% of total serum SC, respectively, in a case of acute hepatitis with a very high serum IgM concentration and in IgA deficiency. The proportions of SC bound to IgM and to polymeric IgA (p-IgA) in the sera correlated with their IgM/p-IgA molar ratio. This suggests that during liver disease, the hepatobiliary tissues could release free SC into the circulation, where it binds to p-IgA and IgM according to their respective concentrations and affinities for SC. The proportion of p-IgA in serum was not increased in four cases of biliary obstruction, in contrast to our cases of cirrhosis and acute hepatitis, indirectly supporting a minor transfer of p-IgA from blood to bile in humans, in contrast to rats and rabbits.

Acute Disease↗
PubMed1982

Secretory component (SC): preferential binding to heavy (greater than 11S) IgA polymers and IgM in serum, in contrast to predominance of 11S and free SC forms in secretions.

The origin and molecular form(s) of the small amounts of secretory component (SC) found in serum are but poorly known. Using sensitive immunoradiometric assays for SC, we studied its molecular distribution after ultracentrifugation of native sera containing various proportions of IgA and IgM, with SC levels (sIgA equivalents) ranging from 4 to 25 micrograms/ml. Large proportions of SC were found bound to IgM and IgA polymers heavier than the classical 11S sIgA, in contrast to saliva and bile where SC was found mainly in the 11S region and in the free form. A comparative study of the ultracentrifugal distribution of labelled free SC, incubated in vitro with sera containing various proportions of IgA and IgM, yielded similar results, indicating a direct relationship between the proportion of IgM-bound SC and the IgM concentration. Free SC in serum was only found in the in vitro experiments. The data suggest that the epithelial cells synthesizing SC not only release (secrete?) SC as pre-assembled SC-Ig complexes in lymph or plasma, but also directly release some SC in free form.

Bile↗
PubMed1981

A solid phase, direct competition, radioimmunoassay for quantitation of secretory IgA in human serum.

A solid phase radioimmunoassay is described for measurement of secretory IgA (sIgA) in human serum. The assay is based on direct competition between sIgA in serum and purified labelled milk sIgA for anti-secretory-component antibodies coated on disposable plastic cups. The assay is relatively rapid, reproducible and of adequate sensitivity. A wide range of sIgA concentrations (5--120 microgram/ml) can be tested with the same dilution of human serum. The arithmetic mean +/- S.D. of the serum sIgA levels of 120 random blood donors (both sexes) was 10.9 +/- 4.6 microgram/ml. Compared to previously published methods and results of quantitation of sIgA in human sera, the present assay is an improvement which should yield interesting data in human hepatic physiopathology.

Blood Proteins↗
PubMedDate not supplied

The liver in the IgA secretory immune system. Dogs, but not rats and rabbits, are suitable models for human studies.

The liver transport of polymeric IgA (pIgA) from plasma into bile and the immunohistochemical distribution of secretory component (SC) in the liver were studied in dogs, and compared to those in humans, rats, and rabbits. Results were as follows: (i) according to bile and serum protein concentrations and specific activities, plasma pIgA in dogs, like in humans, is transported into bile approximately 10 times more efficiently than albumin, as compared to 320 and 1060 times in rabbits and rats, respectively. (ii) Only approximately 1% of an i.v. dose of [125I]pIgA is transported into bile over 8 hr in dogs, like in humans, as compared to approximately 50% over 3 hr in rats and rabbits. These results agree with much smaller daily fractional catabolic rates of intravascular pIgA in dogs (0.28) and humans (0.48) than in rats (24.0). (iii) Total bile IgA contributes daily about 1.5 mg per kg to intestinal pIgA in dogs, a figure similar in humans (0.8 mg per kg) but much smaller than in rats (38 mg per kg) and rabbits (35 mg per kg). (iv) Biliary obstruction in dogs, like in humans, results only in minor and late increases in serum pIgA levels, contrasting with greater than 8-fold increases within 24 hr in rats and rabbits. (v) Unlike in rats and rabbits, SC in dog liver as well as in human liver cannot be detected in hepatocytes although clearly present in bile duct cells. To conclude: (i) major species differences in plasma-to-bile transport of pIgA exist, most probably related to species differences in the ability of hepatocytes to synthetize SC.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Characteristics of serum IgA and liver IgA deposits in alcoholic liver disease.

Patients with alcoholic liver disease frequently reveal an increase in IgA serum concentration and IgA deposits in a continuous pattern along hepatic sinusoids. We investigated whether the hepatic IgA deposits are a passive reflection of changes in concentration or composition of IgA in the circulation, or represent a distinct effect of alcohol on the liver. Forty-one patients with alcoholic liver disease (daily alcohol intake at least 50 gm for more than five consecutive years) were compared with 41 patients with nonalcoholic liver disease. Patients in both groups were matched for serum IgA and histopathological changes in the liver biopsy. IgA deposits in the liver were found in 78% of the alcoholic patients and in 12% of the nonalcoholic patients. The presence of deposits was not related to histopathological changes in the liver or to the serum IgA concentration. In serum IgA subclass distribution, alcoholic patients differed from nonalcoholic patients by a slight but significant shift to IgA2; in contrast, the hepatic IgA deposits in alcoholic patients were almost of the IgA1 subclass. Serum secretory component (which is an equivalent of serum secretory IgA) was elevated in both alcoholic and nonalcoholic patients; patients with a liver biopsy revealing hepatitis showed the highest level. In contrast, the hepatic deposits did not contain secretory component. We conclude that the continuous deposits of IgA along liver sinusoids are not a passive reflection of changes in concentration or composition of circulating IgA, but may represent a distinct effect of alcohol on the liver related to the role of this organ in IgA metabolism.

Biopsy, Needle↗
PubMedDate not supplied

[IgA and its different molecular forms in the mesenteric, portal and peripheral venous blood in man].

The aim of this study was to assess the role of mesenteric blood in polymeric IgA (p-IgA) and IgA2-transport from the intestinal mucosa into plasma and the role of the liver in the clearance of these molecular forms of IgA. The concentrations of IgA, p-IgA and IgA2 were measured in mesenteric, splenic, portal, and hepatic veins of 7 control subjects without liver disease and in portal and peripheral veins of 4 patients with alcoholic cirrhosis. In control subjects, the concentration of the different molecular forms of IgA were not significantly different in mesenteric and in splenic vein. No significant decrease of IgA concentrations was observed in hepatic vein, as compared with portal vein. In cirrhotic patients IgA concentrations were significantly higher than in control subjects, but concentrations of IgA, p-IgA and IgA2 were not different in portal and peripheral blood. These results show that mesenteric vein is not a major way for p-IgA and IgA2 from the gut lamina propria to plasma, and suggest that the origin of a significant part of these molecular forms of IgA could be peripheral lymph-nodes more than gut-associated-lymphoid-tissue. The absence of significant clearance of p-IgA by the liver in normal subjects suggests that abnormalities of hepato-biliary transport of p-IgA is not responsible for the increased IgA levels observed in cirrhotic patients.

Adult↗