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Biomedical subjects

J F Heremans

Publications and source records attributed to J F Heremans.

At least 19 recordsLinked to original sources
PubMed1977

Three immunoglobulin classes in the pigeon (Columbia livia).

Three classes of immunoglobulins have been identified in the pigeon. IgG and IgM were purified from pigeon serum whereas IgA was isolated from pigeon hepatic bile. Pigeon IgG and IgM had the same properties and immunohistological distribution as their chicken homologues. Pigeon IgA was identified on the following grounds: (1) it contains the same light chains as pigeon IgM and IgG; (2) it is relatively abundant in exocrine secretions such as bile, egg white, cropmilk and intestinal fluid, whereas it is present only in small amounts in serum; (3) it occurs in the cytoplasm of the majority of the immunocytes from the intestinal mucosa; (4) its electrophoretic mobility and molecular size are similar to those of chicken IgA. Surprisingly, no immunoglobulin-containing cells could be detected in sections of the wall of the cropmilk gland, despite the high IgA content of the cropmilk.

Animals↗
PubMed1976

Two esterases common to seminal plasma, other external secretions and leucocytes in man.

Two esterases previously identified in seminal plasma, on the basis of their electrophoretic mobility, immunogenicity and sensitivity to organophosphorus esters were detected in various human external secretions and leucocyte extracts. alpha-Esterase was found to be abundant in urine and milk whereas this enzyme occurred in a low concentration in seminal plasma, leucocyte extract, cervical mucus and sweat. The concentration of betagamma-esterase was high in seminal plasma and leucocyte extract. The enzyme was present in small amounts in urine, milk, gastric juice, saliva, sputum, tears, cervical mucus and sweat.

Bronchitis↗
PubMed1976

Detection of circulating antigen-antibody complexes by their inhibitory effect on the agglutination of IgG-coated particles by rheumatioid factor of Clq.

The agglutination of Ig-coated particles by human RF or Clq can be inhibited by Ig aggregates or AgAb complexes. The effect of Ig class was studied by means of agarose-linked human monoclonal Igs. RF was inhibited by all subclasses of IgG and IgA but not by IgM, whereas Clq reacted with IgM, IgG3 and IgG1. Heat-aggregated IgG3 was fractionated by gel-filtration on Ultrogel. Inhibition was restricted to certain fractions of aggregates, viz (IgG3) approximately 7 and (IgG3) approximately 21 for RF, and (IgG3) approximately 10, (IgG3) approximately 14 and (IgG3) approximately 27 for Clq. In a precipitin curve experiment, it was found that RF was inhibited by soluble complexes over an extended range of AgAb ratios, the inactivation of Clq being limited to complexes with 2-5 times antigen excess. Inhibiting factors were found in patients with various diseases and, at low titres, in 22% of healthy people. In 27% of patients' sera, the inhibitors were demonstrable by Clq only after removal of endogenous RF by adsorption on insolubilized IgG. In several patients endogenous agglutinating activity and direct inhibitory activity tended to alternate during the course of the disease. Sera from various patients were also filtrated on Ultrogel and the elution was monitored by immunoassay of IgA, IgM and IgG, as well as by the two inhibition tests. The inhibiting factors were distributed over several peaks which only partially coincided with the elution profiles of IgG and IgM.

Agglutination Tests↗
PubMed1975

A mechanism for the induction of immunological tolerance by antigen feeding: antigen-antibody complexes.

We have previously reported on the induction, in mice, of a systemic (splenic) immune response with IgA as the dominant antibody, as a result of a short (4 day) intragastric immunization course with foreign erythrocytes. This response was followed by a prolonged period of hyporesponsiveness to similarly administered antigen. Here it is shown that this hyporesponsiveness is also manifested towards antigen given intraperitoneally, and that one is therefore dealing with tolerance, not with failure to absorb antigen from the gut. In contrast, mice primed parenterally and then challenged intragastrically behaved as if never having any previous contact with the antigen, i.e., with a primary-type splenic response of predominant IgA character. This agrees with our former conclusion that splenic responses to enterically absorbed antigen reflect colonization of the spleen by cells sensitized locally in the gut wall, a site not readily primed by the parenteral route. Serum from intragastrically immunized mice contained a very active tolerogen. In vivo, it was capable of conferring tolerance to nonimmune recipient mice. In vitro, it paralyzed the activity of antibody-producing cells. Inhibitory sera has weak antibody activity, restricted to the IgA class, and contained immune complexes reacting with rheumatoid factor but not with C1q. Elimination of these complexes by means by insolubilized rheumatoid factor abolished the tolerogenic effect. In conclusion, the enterically induced tolerogen seems to consist of immune complexes with IgA as the antibody.

Animals↗
PubMed1975

Nude mouse embryo: ectodermal nature of the primordial thymic defect.

Sterile female homozygous nude mice were rendered fertile through a graft of thymic epithelium from heterozygous littermates 3 days after birth. Homozygous nude embryos were compared with embryos age (8-18 days). In nude mice, the embryological anomaly is noticeable from the 11th day of gestation and essentially consists of a failure of the ectoderm from the 3rd branchial cleft to proliferate and differentiate into a cervical vesicle. As a result, the endoderm from the 3rd pouch degenerates into cystic formations instead of differentiating.

Animals↗
PubMed1975

[Transferrins in rabbit ocular fluids].

A study of transferrins in serum, aqueous humour, and vitreous in the rabbit suggests that the three proteins are immunologically identical. Electrophoretic and enzymatic analyses indicated that the serum and aqueous transferrin, as well as an important part of that of the vitreous, have two residues of sialic acid per molecule. The remainder of the vitreous transferrin contains little or no sialic acid. The transfferin level in the ocular media appears to depend partly on a local synthesis in the posterior segment; this is confirmed by a study of the specific activity of 125-I transferrin after intravenous injection of this labelled protein.

Animals↗
PubMed1975

Secretory component of the guinea-pig.

Free secretory component (FSC) was purified from guinea-pig milk by gel-filtration and immunoabsorption on anti-SC antibodies. Guinea-pig FSC cross-reacted with antisera to human FSC, and the reverse. Guinea-pig and human FSC resembled each other in molecular size, electrophoretic mobility and heterogeneity, as well as by the existence of antigenic determinants restricted to the unassociated form of the molecule. Guinea-pig FSC associates in vitro with guinea-pig IgM. Distribution of disulphide links is required to set free guinea-pig FSC from secretory IgA.

Animals↗
PubMed1975

Identification and some properties of rat secretory component.

An antiserum, prepared against partially reduced and alkylated rat milk SIgA, was shown to contain antibodies reacting with a rat milk protein of alpha-2 mobility, which possessed antigenic determinants common with SIaA, eluted from Sephadex G-200 at the same position as mammalian secretory components, and could be released from rat SIgA by mild reduction and alkylation. This protein, called rat secretory component, was also detected in saliva, tears and urine. Rat free secretory component (FSC) possessed antigenic determinants which were inaccessible in rat SIgA, as found in other species. In vitro, ra FSC combined with rat serum polymeric IgA or IgM, but not with monomeric IgA or IgG. These data emphasize the many similarities between the human and rat SIgA systems.

Adsorption↗
PubMed1974

The involvement of lactoferrin in the hyposideremia of acute inflammation.

The hyposideremia of inflammation was found to be based on a three-step mechanism involving lactoferrin, the iron-binding protein from the specific granules of neutrophilic leukocytes. (a) Lactoferrin is Released from Neutrophils in an Iron-Free Form. When phagocytosis was induced in neutrophils by zymosan or bacteria, lactoferrin was recovered in the incubation medium together with other constituents of the specific granules, such as alkaline phosphatase and lysozyme. Lactoferrin extracted from leukocytes was able to bind the amount of iron corresponding to its theoretical iron-binding capacity. After injection of endotoxin into rats, lactoferrin was detected in various tissues where it was normally absent, or in the plasma when the reticuloendothelial system (RES) had previously been blocked by injections of India ink or aggregated albumin. (b) Lactoferrin is Able to Remove the Iron from Transferrin. Significant exchange of iron from transferrin to lactoferrin was observed in vitro only at a pH below 7.0 or in the presence of a high concentration of citrate. However, the fast elimination of lactoferrin in vivo, when saturated with iron, might account for the observed transfer of iron to endogenous or administered apolactoferrin. Intravenous injection of human apolactoferrin into rats caused a marked decrease of the plasma iron level. The kinetics of this process, as well as controls with other proteins, ruled out the possibility of a secondary inflammatory effect due to phlogogenic contaminants. (c) Fe-Lactoferrin is Taken-up by the RES. By immunofluorescence, lactoferrin was shown to be bound and ingested by monocytes. The rate of elimination of human Fe-lactoferrin injected into rats was particularly fast when compared to that of human apolactoferrin, succinylated Fe-lactoferrin, or other human proteins. Blockade of the RES slowed down the rate of clearance of Fe-lactoferrin and was also found to retard the elimination of endogenous rat lactoferrin released by endotoxin. These experiments suggest the existence of specific receptors for Fe-lactoferrin on the membrane of macrophages.

Animals↗