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R Kulhavy

Publications and source records attributed to R Kulhavy.

30 records · Page 2Linked to original sources
PubMed1978

Secretory component of epithelial cells is a surface receptor for polymeric immunoglobulins.

Epithelial cells of human fetal intestines and of a colonic carcinoma cell line (HT-29) exhibited intracellular and surface binding of polymeric immunoglobulins of IgA and IgM classes; monomeric IgA and IgG did not bind to these cells. Secretory component was identified as the receptor involved in the immunoglobulin binding. This conclusion was confirmed by the following experiments: trypsin abrogated the surface binding of polymeric immunoglobulin, reappearance of surface secretory component (SC) restored immunoglobulin binding; the appearance of SC in developing fetal tissues coincided with their potential to bind polymeric immunoglobulin; anti-SC reagents inhibited the binding of immunoglobulins to epithelial cells; and SC-containing secretory IgA did not bind to the surface of HT-29 cells.

Cell Membrane↗
PubMed1978

Molecular-cellular interactions in the secretory IgA system.

1) SC receptors were not detected on the surface of human PBL before or after PWM stimulation or on the surface of established lymphoblastoid cell lines. 2) SC binding was detected in the cytoplasm of differentiated lymphoid cells. The majority of the SC-binding cells contained intracellular IgA. 3) The binding of polymeric IgA to the surface of human epithelial cells (colonic carcinoma HT-29) was dependent on the presence of SC. 4) These findings indicate that SC is a receptor and possible transport protein for polymeric immunoglobulins, but that it is not directly involved in the homing of the IgA precursor cells to secretory tissues.

Binding Sites↗
PubMed1977

Properties of IgA myeloma proteins isolated rom sera of patients with the hyperviscosity syndrome.

Sera, purified myeloma proteins, and urinary proteins obtained from eight patients with igA multiple myeloma were studied by physical-chemical and immunochemical methods. In six patients whose serum viscosity was increased, the sedimentation constants of the principal component of myeloma proteins ranged from 9.1 to 10.2 S. In two patients with nearly normal serum viscosity, the sedimentation constants of these proteins were 6.2 and 7.2 S. IGA-albumin complexes were detected in most of the sera, but invarying amounts; no complexes of ig with amylase, secretory component, or alpha(1)-antitrypsin were observed. Studies on isolated myeloma proteins revealed that all igA proteisn from sera with increased viscosity represented true polymers, linked by disulfide bonds, rather than noncovalently associated aggregates; J chain was detecable by both alkaline-urea disc electrophoresis and immunoelectrophoresis with a monospecific anti-J chain serum. Increased serum viscosity was not related to the igA subclass, L chain type, or the carbohydrate compositions of individual igA myeloma proteins. The urine of five patients contained free light chains corresponding in type to the light chain of the particular igA myeloma protein. However, free J chain was not detected. The immunoelectrophoretic analysis for the presence of J chain in sera of myeloma patients may be used for early and simple detection of polymeric forms of myeloma proteins.

Aged↗
PubMed1975

Identification and properties of J chain isolated from catfish macroglobulin.

After the cleavage of disulfide bonds of macroglobulin isolated from channel catfish (Ictalurus punctatus), an electrophoretically fast-moving polypeptide, which resembled human J chain, was released. On a Sephadex G-200 column equilibrated in 5 M guanidine, the elution position of the J chain overlapped with the descending part of the L chain peak. Further purification was achieved by DEAE ion-exchange chromatography. The isolated polypeptide, which had a molecular weight of 14,800 +/- 500, as determined ultracentrifugally by sedimentation equilibrium in 5 M guanidine, contained 7% carbohydrate with one residue of fucose, two of mannose, one of galactose, two of glucosamine, and one of sialic acid per chain. A comparison of catfish and human J chain amino acid analyses showed the former to have a higher content of serine, glycine, and phenylalanine and a lower content of aspartic acid, isoleucine, and arginine. Tryptic peptide maps of catfish and human J chains revealed very few common peptides. Rabbit and guinea pig antisera to human J chain did not cross-react with catfish J chain. Untreated, resuced and alkylated, S-sulfonated, or cyanogen bromide cleaved macroglobulin from the gar (Lepisosteus osseus) contained no polypeptide analogous to either catfish or human J chain by the criteria employed in this study.

Acetates↗
PubMed1974

Site of J chain attachment to human polymeric IgA.

A fragment containing J chain was released from human polymeric myeloma IgA protein by cyanogen bromide cleavage. The identity of the fragment was determined by its electrophoretic mobility and antigenic determinants. After purification by gel filtrations and DEAE-Sephadex chromatography, this fraction appeared similar (with respect to its amino acid and carbohydrate compositions and its peptide maps) to the J chain isolated from this IgA protein; the molecular weight was 17,000 +/- 100. Upon reduction and alkylation, with subsequent separation of peptides by gel filtration, three components were obtained: the largest component (molecular weight 13,400) corresponded to the N-terminal segment of J chain and contained a homoserine residue, the second corresponded to the C-terminal part of J chain with 13-18 amino acid residues, and the third corresponded to the C-terminal octapeptide of the alpha chain. The data indicate that J chain is attached to alpha chain(s) through the penultimate cysteine residue of the C-terminal octapeptide.

Amino Acids↗
PubMedDate not supplied

The role of the liver in catabolism of mouse and human IgA.

The fate of intravascular IgA which is produced in large quantities in humans and many animal species was investigated in vivo and in vitro with emphasis on the monomeric form of IgA. The site(s) of the catabolism of intravenously injected mouse monomeric IgA labeled with a residualizing tracer (dilactitol - 125I tyramine) was studied in mice. The greatest in vivo uptake of monomeric IgA was observed in the liver. In contrast to identically labeled IgG, liver accounted for more internal catabolism of monomeric IgA than all other tissues (spleen, muscle, skin, and kidney) combined. Although both parenchymal and nonparenchymal liver cells internalized monomeric IgA, hepatocytes were far more active. The uptake of monomeric IgA was primarily mediated by the asialoglycoprotein receptor. In humans, the particulate fraction of liver homogenates and a human hepatoma cell line (Hep G2) bound human IgA proteins of various molecular forms. Inhibition of the binding by desialylated glycoproteins, requirement for the presence of calcium, and the molecular properties of the IgA-binding protein from the plasma membrane of Hep G2 cells indicated that the binding was primarily mediated by the asialoglycoprotein receptor. IgA proteins bound by Hep/G2 cells were internalized and catabolized to low molecular weight fragments.

Animals↗