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A Bourgois

Publications and source records attributed to A Bourgois.

6 recordsLinked to original sources
PubMed1979

Identification of an IgD-like surface immunoglobulin on rabbit lymphocytes.

Rabbit immunoglobulin antigen receptor molecules were analyzed by electrophoresis in sodium dodecyl sulfate polyacrylamide gels. By sequential precipitation, using first anti-mu and then anti-L chain antisera, two different immunogloublins of similar molecular weight could be demonstrated. After tryptic digestion, two fractions were identified: an IgMs and an Fab fragment, the latter appearing after a few minutes of incubation. Thus, as in man and in the mouse, two main immunoglobulin antigen receptors were found in the rabbit. One receptor on rabbit lymphocytes is an IgMs molecule, and the other is easily split in the hinge region like human and mouse IgD receptors. In addition, a molecule similar to the mouse Fc receptor was nonspecifically precipitated.

Animals↗
PubMed1977

Surface immunoglobulins of lipopolysaccharide-stimulated spleen cells. The behavior of IgM, IgD and IgG.

The nature of Ig receptors carried by lipopolysaccharide (LPS)-stimulated mouse spleen B cells was analyzed by surface iodination, direct antiserum precipitation and polyacrylamide gel electrophoresis. LPS activation led to a rapid decrease of surface IgD to 20 % and 80 % of the original level on days three and five of culture, respectively. Efficiency of iodination of cells doubled after culture but the proportional radioactivity in IgM reace of cells, but only in small amounts (1 % of total surface Ig) and this expression of IgG remained constant during 5 days of culture. We could definitively identify gamma-chains on the surface of cells, but only in small amounts (1% of total surface Ig) and this expression of IgG remained constant during 5 days of culture.

Animals↗
PubMed1977

Mouse immunoglobulin receptors on lymphocytes: identification of IgM and IgD molecules by tryptic cleavage and a postulated role for cell surface IgD.

The two mouse immunoglobulin receptors on lymphocytes (IgM and IgD-like) were individually digested by trypsin. The tryptic susceptibility, and the products released, were similar to those of their human counterparts. Evidence for a structural homology between human IgD and its presumed mouse conterpart has been provided by the ramarkably similar profile of fragments resulting from digestion. More definitive homology awaits sequence determination. The extreme susceptibility of surface IgD to proteolysis contrasted with the resistance of surface IgM. We therefore propose that the major role of IgD is to release a fragment (Fabdelata) following exposure to antigen and then elicit a regulatory anti-idiotype response which acts through recognition of the protease-resistant IgM idiotype remaining on the cell surface.

Animals↗
PubMed1977

Structure of mouse Fc receptor.

A variety of mouse cell types were externally labeled with radioactive iodine and solubilized in detergent. A single chain radioactive molecule of mol. wt. 120 000 was precipitated from lysates of surface-labeled lymphocytes, macrophages and fibroblasts by complexes between pneumococcal type 3 polysaccharide and its homologous rabbit antibody in the IgG form, but not as F(ab')2 or Facb. The same results were obtained using an alternative precipitating system, namely ovalbumin and IgG and F(ab')2 forms of rabbit anti-ovalbumin. The 120 000 mol. wt. compound could not be detected on a thymoma cell line (5178) previously known to lack the Fc receptor. On the basis of these criteria the material was therefore identified as mouse Fc receptor. Although very susceptible to proteolysis, the fragments resulting from digestion remain associated by disulfide bonds in such a way as to still bind to the antibody-antigen precipitate. The proteolytic fragmentation products (mol. wts. 75 000, 45 000, 20 000 and 10 000) only become apparent upon chemical reduction, but the ease with which the molecule is degraded explains the wide variation in mol. wts. reported for the Fc receptor, and is perhaps a clue to explain the biological role of the molecule.

Animals↗
PubMedDate not supplied

Structural and functional mapping of immunoglobulin V-regions.

V-regions of immunoglobulins chains contain 3 types of positions, which are equally represented: invariant and sub-group characteristic, which account for the "framework" and hypervariable positions, responsible for antigen recognition. The 3 types of positions are grouped and fall within a very few discrete stretches. Sub-group characteristic segments containing one of the 2 cysteyl residues of the V-regions may be isolated by high voltage paper electrophoresis and provide a basis to type for sub-groups in the VK and in the VH human systems. This allowed to characterize a large set of human myeloma proteins that were used in a series of competitive hybridizations which indicated that sub-groups had no influence on preferential reassociations, which occurred in 80% of the cases. This preference seems to rely mostly on individual structural differences, which may be linked to heterogeneity at the framework level. Distinction between framework heterogeneity and hypervariable regions heterogeneity may be approached by raising antibodies against a mouse myeloma protein, MOPC 173, of known sequence, by means of syngeneic and allogeneic immunizations, using Balb/c and A/J mice. Junction of distinct portions of immunoglobulin chains such as the V and the C regions raises the possibility that some recognition signals may operate at the DNA level. Since rotational symmetry regions in the DNA are known to act as such signals, it is discussed whether such regions can be expected from the amino acid sequence data, especially in the vicinity of the "switch" peptide.

Amino Acid Sequence↗