Kinetics of digoxin and anti-digoxin antibody fragments during treatment of digoxin toxicity

Anti-digoxin antibody fragments (ADAF, 80 mg) were infused intravenously to successfully treat severe digoxin toxicity in an 82 year old woman. During treatment, total and free digoxin were determined using an Abbot TDX analyser and an ultrafiltration technique. ADAF were measured by an enzyme-linked immunosorbent assay. By 1 h after ADAF, total serum digoxin concentrations had risen 12-fold from a pretreatment level of 15.4 nmol l-1 but free digoxin fell from 10 to 0.1 nmol l-1, indicating greater than 99.9% digoxin binding to ADAF. However, the low free levels had rebounded to 7.7 nmol l-1 by 12 h, but despite this rise the patient's condition had improved. A serum ADAF/digoxin molar ratio of around five was associated with the low concentration of free digoxin at 1 h, while at later times with ratios roughly between 3 and 4, the free digoxin concentrations ranged between 2.0 and 7.7 nmol l-1. ADAF were mainly confined to the plasma during the first hour, but subsequently distributed into an apparent volume of 193 ml kg-1. The elimination half-lives of ADAF and total digoxin were 96 and 55 h, respectively. More than 50% of the estimated digoxin load had been excreted in the urine by 5 days; for ADAF the equivalent figure was only about 3%. Renal and/or bacterial degradation may have contributed to the low detection of urinary ADAF.

Predilection of a nasopharyngeal carcinoma-derived isolate of Epstein-Barr virus for infection of specific subsets of B lymphocytes

It is important to know whether there are variants of Epstein-Barr virus (EBV) with biological properties that are different from the prototype viruses that have been studied in detail, such as P3HR-1 and B95-8. We have studied an EBV isolate derived from a nasopharyngeal carcinoma (NPC) tumor, designated NPC-EBV. We have examined the target B lymphocytes infected and growth-transformed with NPC-EBV as compared with two common EBV isolates, B95-8 and AG876 EBV, for stage of maturation using antibodies to several immunoglobulin chains. Typing of the NPC-EBV transformed lymphoblastoid cell lines revealed the predilection of the NPC-EBV isolate to infect immature B lymphocytes. This was not the case for the B95-8 and AG876 isolates. The reason for the predilection of NPC-EBV for immature B lymphocytes remains to be explored further. However, these results may be important in understanding the pathophysiology of EBV-associated diseases.

Detection of IgA protease from Haemophilus influenzae by immunoblotting

IgA protease produced by various strains of Haemophilus influenzae can digest serum IgA and yield its fragments which can react with anti-IgA serum. We assayed IgA protease activity by detecting the digests of IgA by SDS-PAGE and immunoblotting. The digests were separated with SDS-PAGE, transferred to nitrocellulose membranes and detected with anti- (alpha chain of human IgA, its Fab and its Fc) immunoglobulin conjugated peroxidases. Using this method, we can determine which type of IgA protease is produced by various of H. influenzae strains. All the 20 strains isolated from respiratory tracts produced IgA protease.

Secretory component and immunoglobulins in the intrahepatic biliary tree and peribiliary gland in normal livers and hepatolithiasis

Distribution of secretory component (SC), IgA, IgM and joining chain (J chain) in the intrahepatic biliary epithelium and peribiliary glandular epithelium were studied in normal livers and hepatolithiasis. In normal livers, SC was immunohistochemically demonstrated homogeneously in the cytoplasm of the biliary lining and peribiliary glandular epithelium. Immunoelectron-microscopically, SC was localized in the basolateral plasma membranes, nuclear membranes, rough endoplasmic reticulums, Golgi complexes and intracytoplasmic small vesicles, suggesting that the biliary lining and peribiliary glandular epithelium has an ability to synthesize SC. On the other hand, IgA and IgM were found heterogeneously in the biliary lining epithelium, and immunoelectron-microscopically they were only localized in the basolateral plasma membranes and vesicles. J chain was found in similar portions, suggesting that IgA and IgM in biliary lining and glandular epithelium were polymeric. It seems likely that polymeric IgA and IgM combine with SC on the biliary lining and glandular epithelial membranes, and subsequent endocytic transport and secretion of these complexes into the bile occur. In hepatolithiasis in which biliary living epithelia are hyperplastic and peribiliary glands proliferate markedly, such endocytic transport and secretion seemed to be increased. From these findings, it was suggested that the peribiliary glandular as well as biliary lining epithelium contributes to a local immunity in the biliary tree, especially in hepatolithiasis.

Immunohistochemical localization of secretory component and immunoglobulin A in the urogenital tract of the male rodent

The mucosal immune system in the male rodent urogenital tract was studied by localizing secretory component (sc) in the rat and immunoglobulin A (IgA) in both rat and mouse by immunofluorescence. In the rat, bright labelling of sc was observed at several sites, including the ejaculatory ducts, excretory ducts of several accessory glands, and urethral glands in the pelvic and bulbous portions of the urethra. Pale labelling of sc was detected in epithelial cells of the ventral prostate gland. Plasma cells containing IgA were only observed in the urethral gland in the bulbous portion of the urethra in rats and mice. These results suggest that IgA may be transported into the urogenital tract of the male rat primarily at sites distal to the production of seminal fluid and spermatozoa. While locally synthesized IgA may be available in the bulbous urethra, it appears that serum may be the main source of IgA for transport into the rat urogenital tract at the other sites where its receptor, sc, was demonstrated.

Immunohistochemical investigation of secretory component and immunoglobulin A in the genital tract of the female rat

There was intense labelling of secretory component (sc) in the glandular and luminal epithelia of the uterine horns at pro-oestrus, oestrus and Day 1 of pregnancy, but at other stages labelling was weak or undetectable. There was also intense labelling of sc in the superficial layer of cells in the stratified epithelia of the cervix and vagina at pro-oestrus and Days 4-7 of pregnancy, but not at other stages. Plasma cells containing immunoglobulin A (IgA) were not observed in any region of the genital tract at any of the times studied. The presence of sc coupled with an absence of IgA-containing plasma cells suggest that IgA in genital tract secretions of the female rat may be derived mainly from serum.

Rapid selection of cultured cells with increased expression of a membrane marker (secretory component)

This study showed how immunomagnetic monodisperse microspheres (Dynabeads) can be used for rapid selection of stable and homogeneous sublines of cancer cells. The beads were activated with antibody to a specific surface membrane marker. We used a monoclonal antibody (MAb) to human secretory component (SC), the epithelial receptor for polymeric immunoglobulins (pIg). A relatively low number of particles favored rosetting of strongly positive cells. SC-expressing cells were isolated within 30 min from a colonic carcinoma cell line (HT-29.E10). After 13 months of continuous culture the selected cells had a 15 times higher cellular content and a 10 times higher secretory rate of SC than parallel cultures of the original cell line. Immunomagnetic microspheres can be recommended in experimental cancer research, e.g., in order to minimize cellular heterogeneity and to isolate cells with particular surface membrane phenotypes in differentiation studies. The selection method is rapid and simple, and eliminates laborious test systems for conventional subclone screening.

High serum levels of secretory component in hepatocellular carcinoma

PURPOSE

Elevated levels of secretory IgA (S-IgA) have been detected in serum samples from patients with liver diseases and neoplasia with liver metastasis. We undertook the current study in order to determine the concentrations of different forms of free secretory component (SC) in sera from patients with hepatocellular carcinoma.

MATERIALS AND METHODS

The concentrations of SC, S-IgA, and secretory IgM (S-IgM) were quantified in the sera of 100 patients with hepatocellular carcinoma, and in 77 matched healthy control subjects by using an enzyme-linked immunosorbent assay.

RESULTS

Free SC serum levels exceeded the upper limits of control values in 82 percent of patients with hepatocellular carcinoma, S-IgA levels in 88 percent of them, and S-IgM levels in 32 percent. Free SC levels were positively correlated with S-IgA and S-IgM levels. They were weakly correlated with gamma-glutamyl transpeptidase activity, but not with alpha-fetoprotein, beta 2-microglobulin, albumin, or IgA serum concentrations, nor with alkaline phosphatase activity.

CONCLUSION

The data clearly demonstrate the elevation of serum free SC concentrations as a novel biologic alteration in hepatocellular carcinoma since free SC levels appear to be correlated neither with tumor markers (alpha-fetoprotein, beta 2-microglobulin) nor with biliary obstruction.

Immunoelectron microscopical localization of immunoglobulins, secretory component and J chain in the human minor salivary glands

Localization of IgA, secretory component (SC) and J chain was investigated immunocytochemically in minor salivary glands of the lip and palate to define the mechanism involved in the transport of immunoglobulin A (sIgA) into the saliva from the minor salivary glands. SC synthesis was detected in mucous acinar cells and ductal epithelial cells. Free SC is secreted into the saliva through secretory granules in the mucous acinar cells. Dimeric IgA containing J chain is translocated through these cells as sIgA by a SC-mediated transport mechanism involving cytoplasmic vesicles.

Prognostic value of immunohistochemically identified CEA, SC, AFP, and S-100 protein-positive cells in gastric carcinoma

Gastric tissues from 85 patients with advanced carcinoma were studied immunohistochemically for localization of carcinoembryonic antigen (CEA), secretory component (SC) and alpha-fetoprotein (AFP), and for S-100 protein-positive cells. Our objective was to determine if these factors could serve as prognostic indicators. Forty patients died of recurrence or metastases within 2 years (Group I), and the remaining 45 survived 10 years or longer (Group II) after resection. CEA-positive cells were present in 93% and 89% of Groups I and II, respectively. In case of staining for CEA, positive results were seen not only in the malignant cells but also in the stroma in 35% of Group I but none in Group II. The immunohistochemical status of SC was not essentially different between Groups I and II; the positive staining was recognized in 50% and in 57%, respectively. Gastric carcinomas rarely reacted to AFP. S-100 protein-positive cells, which play an important role in local immunity, were often present in Group II (47%) but rarely in Group I (10%). Thus, in addition to the various prognostic factors available to the surgical pathologist, the presence of CEA and the appearance of S-100 protein-positive cells in tumor tissue will aid in predicting the prognosis of patients with advanced gastric carcinoma.

Expression of IgA and secretory component in the normal and in adenocarcinomas of Fallopian tube, endometrium and endocervix

The occurrence and localization of IgA and secretory components (SC) were examined in the normal and in adenocarcinomas of Fallopian tube, endometrium and endocervix. IgA-containing immunocytes were identified in the stroma of 90% of normal Fallopian tubes. It is suggested that the Fallopian tube may have an immunological function and may, together with the endocervix, constitute the local secretory immune system of the female genital tract. IgA and SC were frequently demonstrated in the cytoplasm and luminal secretion of adenocarcinomas of the endocervix, endometrium and Fallopian tube. This study has shown a decrease in immunoreactivity of SC among poorly differentiated adenocarcinomas but has failed to demonstrate any correlation between the expression of IgA and the degree of differentiation of the tumours. Secretory component appears, therefore, to be more useful than IgA as an indicator of secretory activity and differentiation of adenocarcinomas of the female genital tract.

Rabbit secretory components of different allotypes vary in their carbohydrate content and their sites of N-linked glycosylation

The asparagine-linked glycosylation sites in rabbit high and low Mr secretory components (SC) have been determined for the three known allotypes, t61, t62, and t63. Purified SC polypeptides were subjected to mild periodate oxidation of terminal nonreducing sugars followed by selective reduction with [3H]sodium borohydride, SC polypeptides were further proteolytically cleaved, and the 3H-labeled peptides were isolated and characterized. Both high and low Mr SCs of the three allotypes possess a common glycosylation site at the asparagine residue position 400, whereas the second site, in the amino-terminal domain of SC, was found to be variable: the t61 and t63 allotypes contained a glycosylation site at positions 70 and 90, respectively. Moreover, although the t62 allotype was found to contain a triplet acceptor site (N-X-S) at positions 90-92, analyses showed that less than 30% of the t62 allotype peptides encompassing this region were glycosylated at residue 90. Furthermore, the amino acid sequence of the t61 SC in the region of residues 69-90 varies by 8 and 10 amino acid substitutions when compared with the t62 and t63 allotype sequences, respectively. However, neither the variation in amino acid sequence nor the variation in degree or site of glycosylation measurably affected the non-covalent binding of domain 1 to dimeric IgA.

Ionic binding properties of carrier ampholytes

Radioactive ampholytes were synthesized with specific activity of 638 microCi/g. These were used in studies of ampholyte binding to target proteins under non-ionic conditions. These radioactive ampholytes bound to target proteins but were dissociable in sodium chloride solutions with dissociation occurring in a concentration dependent way. The ampholytes could be dissociated from target molecules using excess unlabelled ampholytes synthesized in the laboratory as well as commercial ampholytes. Radioactive ampholytes were bound to target proteins with different isoelectric points and the bound ampholytes were eluted and analyzed by recycling isoelectric focusing. The results showed that acidic proteins bound basic ampholytes and basic proteins bound acidic ampholytes. Acidic radioactive ampholytes were selectively bound by Sephacryl S-200 and ampholyte exchange from protein to Sephacryl S-200 was shown.

The effect of aging on the secretory immune system of the eye

The objective of the present study was to examine the influence of aging on the ocular secretory immune system of the eye. Levels of IgA and free secretory component (FSC) were measured in lacrimal glands and/or tears of 0.6, 1.3, 3, 8 and 17-month-old male and female rats. In addition, the FSC output of lacrimal tissue cultured in vitro was evaluated. During the period from 0.6 to 1.3 months of age, the content of tear IgA increased nine- and 13-fold in females and males, respectively. This rise was paralleled by changes in the concentration of tear FSC. Prior to the onset of puberty, FSC could be detected in only 7% of tear samples, whereas after pubertal maturation, tear FSC levels had attained adult concentrations. This tear FSC profile was similar to the age-related pattern of FSC output by lacrimal tissue incubated in vitro. Following puberty, tear IgA content continued to increase in both sexes until adulthood (3 months of age) and then plateaued in females from 8 to 17 months of age. In contrast, tear IgA in males appeared to stabilize from 3 to 8 months and then rose significantly to the highest levels at 17 months of age. This increase in males was also reflected in their lacrimal tissue: IgA content underwent a six-fold elevation from 3 to 17 months. Of interest is that the differential kinetics involved in tear IgA and FSC expression resulted in an age-associated decline in the FSC/IgA ratio from post-puberty to senescence. A striking finding in these studies was the persistence of a sexual dimorphism in the secretory immune system of the eye. After pubertal development, IgA and FSC levels were significantly higher in tears of males, compared to those of females, at all ages tested up to 17 months. These gender- and age-related variations in tear IgA and FSC amounts could not be accounted for by changes in either the volume of, or total protein content in, tears.

Lack of relation between expression of HLA-DR and secretory component (SC) in follicle-associated epithelium of human Peyer's patches

Follicle-associated epithelium (FAE) of normal human Peyer's patches (PP) was studied with regard to expression of HLA-DR determinants and secretory component (SC); the latter acts as a receptor for polymeric immunoglobulins (pIg). Putative M cells were identified in FAE by lack of a brush border with alkaline phosphatase. These cells were virtually negative for HLA-DR whereas the remaining FAE was strongly positive like villous epithelium. Conversely, the complete FAE showed no SC expression and was negative for IgA. These findings suggested that the FAE (including the M cells) does not participate in SC-mediated transport of pIgA, which in the gut mainly takes place through columnar crypt cells. The FAE (excepting the M cells) may be involved in an MHC class II-restricted antigen-presenting function as recently suggested for villous epithelium. The role of M cells may hence be limited to uptake and transport of luminal antigens.

Sandwich-type ELISA for free and bound secretory component in human biological fluids

Three sandwich-type enzyme-linked immunosorbent assays (ELISA) are described for the measurement of free secretory component (SC) and SC bound to IgA (S-IgA) or IgM (S-IgM). These assays do not require preliminary fractionation of the biological fluids to be tested. The specificity of the assays is achieved with monoclonal antibodies specific for free SC (855 SC) and for SC bound to IgA or IgM (8545 SA). The amount of the three SC molecules in various biological fluids is reported. We demonstrate the presence of low levels of free SC in most of these fluids, including normal serum. Moreover our results suggest that S-IgM in serum may result from a non-covalent association between serum IgM and free SC.

Is there any tubular secretion of protein?

Immunohistological investigations performed with the PAP method on tubular casts in the thick Henle loops and in the distal convoluted tubules led to the following results. 1) In control kidneys, casts consisting of sIgA and IgM occur, mostly isolated, in 30% and 20%, respectively, of cases. On the other hand IgG casts, likewise isolated, are only observed in 7% of cases. 2) In the case of mesangioproliferative glomerulonephritis of the IgA and non-IgA nephritis type, casts consisting of sIgA and IgM are observed more often than in control kidneys, especially when the serum creatinine concentration exceeds 1.3 mg%; i.e., the glomerular filtration is reduced. 3) In kidneys with inflammatory and non-inflammatory glomerular diseases which had led to nephrotic syndrome, casts consisting of sIgA and IgM are not observed more often than in kidneys with glomerulonephritides which had not been accompanied by nephrotic syndrome. 4) In kidneys with severe impairment of the excretory function (rapidly-progressive glomerulonephritis, primary malignant nephrosclerosis, acute renal failure) casts consisting of sIgA and IgM are observed more often than in controls but not more often than in IgA and non-IgA nephritides with increased serum creatinine concentration. 5) In kidneys which had become aglomerular as a result of scarring of the glomeruli, with atrophic proximal tubules and preserved epithelia of the ascending loop of Henle, casts consisting of sIgA and IgM as well as secretory component occur in a large quantity.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of the hypothalamic-pituitary axis on the androgen regulation of the ocular secretory immune system

The purpose of the present investigation was to examine the influence of the hypothalamic-pituitary axis on the androgen regulation of the ocular secretory immune system. Studies included the following experiments: (1) Testosterone administration significantly increased the immunoglobulin A (IgA) and free secretory component (SC) levels in tears of adult, orchiectomized and sham-hypophysectomized rats, as compared with those in tears of saline-treated controls. (2) Hypophysectomy completely inhibited this androgen effect. (3) Transfer of the pituitary to under the kidney capsule in orchiectomized and hypophysectomized rats did not restore the physiological conditions required for testosterone's stimulation of tear IgA and SC. (4) Selective ablation of the anterior pituitary gland also interfered with the testosterone-induced elevation of tear IgA and SC content. (5) Treatment of orchiectomized and/or hypophysectomized rats with rat prolactin, growth hormone, alpha-melanocyte-stimulating hormone or vehicle for 4 days had no effect on tear SC and/or IgA levels. Overall, these findings demonstrate that an intact hypothalamic-pituitary axis either supports or mediates the androgen control of the secretory immune system in the eye.

The intraperitoneal delivery of radiolabeled monoclonal antibodies: studies on the regional delivery advantage

The i.p. delivery of murine monoclonal antibody was compared with i.v. delivery in normal mice and rats, in normal nude mice and in those with i.p. human ovarian carcinoma xenografts. In normal rats, all classes of antibodies and antibody fragments evaluated were cleared from the peritoneal cavity at comparable rates. The regional delivery (Rd1) advantage to the peritoneal cavity following i.p. delivery was thus most dependent on the rate of clearance of the antibody or fragment from the blood stream. Determining the exact i.p. delivery advantage was problematic due to the difficulty in reliably obtaining peritoneal fluid later than 9-10 h after i.p. injection in normal animals. During the first 9 h following i.p. injection, the Rd(0-9/0-9) was, for a murine IgG2ak Fab greater than F(ab')2 greater than IgG (at 13.6 greater than 10 greater than 7.9). Two murine IgMs evaluated differed in Rd(0-9) at 27.1 and 9.2 respectively. When blood levels were extrapolated to infinity, these Rd (0-9/affinity) values were considerably lower with the Fab having the highest Rd at 4.67. The i.p. Rd advantage was almost solely due to the i.p. antibody levels seen in the first 24 h after injection, as after that time, blood levels become comparable to those seen following i.v. injection. Normal tissues obtained at sacrifice 5-7 days after i.p. injection. Normal tissues obtained at sacrifice 5-7 days after i.p. or i.v. injection in rats showed comparable levels of radioantibody activity, whether the injection was i.p. or i.v. (except for higher diaphragmatic levels following i.p. delivery). In nude mice with i.p. human-derived ovarian tumors, intact IgG clearance from the peritoneal cavity to the blood was considerably slower than in normal animals, and early i.p. tumor uptake of specific antibody was significantly higher than that following i.v. antibody delivery. With higher early tumor uptake and lower systemic exposure, early tumor/nontumor ratios were significantly greater than those for i.v. delivery, though not beyond 48 h after i.p. injection. This study demonstrates the pharmacokinetic rationale for i.p. monoclonal antibody delivery, especially for agents cleared rapidly from the blood, such as antibody fragments. In addition, definite i.p. delivery benefit for antibody specific to i.p. tumors in the i.p. ovarian cancer system was shown soon after injection. These data regarding i.p. antibody delivery should be useful in rationally planning diagnostic and therapeutic studies involving the i.p. delivery of unmodified and immunoconjugated monoclonal antibodies.

Immunohistological localization of IgG1, IgA and secretory component in the bovine mammary gland during involution

Immunoperoxidase methods were used to localize secretory component, immunoglobulin A and immunoglobulin G1 in mammary tissue from dairy cows. In lactating tissue, immunostaining for immunoglobulin A and secretory component was observed primarily in the luminal contents of alveoli. By day 2 of involution, alveolar epithelial cells stained for both immunoglobulin A and secretory component. Staining of alveolar epithelial cells for immunoglobulin A and secretory component continued throughout the period of mammary involution. No staining for secretory component was observed in the interalveolar stromal area. Immunoglobulin G1 immunostaining was localized primarily in the interalveolar areas in lactating tissue, but was localized at the apical and basolateral surface of alveolar cells on day 2 of involution. In contrast to immunoglobulin A, immunoglobulin G1 staining of epithelial cells did not persist and was primarily in the interalveolar areas by day 4. These results suggest that an increased localization of immunoglobulin G1 in bovine mammary epithelial cells may occur transiently in early involution, while an increase in immunoglobulin A and secretory component localization in epithelial cells persists throughout involution.

[Molecular composition of the fractions of immunoglobulin preparations studied by gel filtration]

The method of gel filtration in columns permitted the separation of aggregated fractions into polymers whose content did not exceed 10% and dimers, their content ranging from 3.6% to 22.11%. The preparations were also found to contain fractions of monomers and fragments, Fab-fragments being detected in 10 out of 20 batches under study (4.04-27.36%). The shelf life of all preparations did not exceed 8-12 months. The use of spectrophotometric techniques ensured obtaining the most objective results in the calculation of the percentage of fractions contained in immunoglobulin preparations. The evaluation of the molecular composition of immunoglobulin preparations by the method of gel filtration is conducive to the improvement of their quality.