scholarly journals COMPLEMENT-DEPENDENT RELEASE OF IMMUNE COMPLEXES FROM THE LYMPHOCYTE MEMBRANE

1973 ◽  
Vol 138 (3) ◽  
pp. 495-507 ◽  
Author(s):  
Gary W. Miller ◽  
Paul H. Saluk ◽  
Victor Nussenzweig
Keyword(s):  
Cell Membrane ◽  
B Lymphocytes ◽  
Immune Complexes ◽  
Mammalian Species ◽  
Normal Serum ◽  
Soluble Antigen ◽  
Lymphocyte Membrane ◽  
Alternate Pathway ◽  
Extensive Degradation ◽  
Antigen Antibody

Soluble antigen-antibody-complement complexes bound to mouse B lymphocytes are rapidly released from the cell membrane in the presence of normal serum from several mammalian species. The release is not the result of antigen-antibody dissociation or extensive degradation of the complexes. However, the released complexes have been altered because they will no longer bind to fresh lymphocytes. The release is not the result of lymphocyte damage mediated by complement. It is complement-dependent, and is generated either preferentially or exclusively via the alternate pathway, since it occurs in C4-deficient serum, is Mg++ but not Ca++ dependent, and requires C3 proactivator. C3 inactivator is not involved. The release activity of the serum, once generated, is unstable at 37°C. The release of complexes from the lymphocyte membrane by serum provides a convenient assay for the functioning of the alternate pathway in the mouse and in other species.

scholarly journals The effect of complement on the ingestion of soluble antigen-antibody complexes and IgM aggregates by mouse peritoneal macrophages.

1978 ◽  
Vol 148 (4) ◽  
pp. 903-914 ◽  
Author(s):  
J L van Snick ◽  
P L Masson
Keyword(s):  
Immune Complexes ◽  
Degradation Products ◽  
Fc Receptors ◽  
Peritoneal Macrophages ◽  
Soluble Antigen ◽  
Complement Receptors ◽  
Human Transferrin ◽  
Particulate Antigen ◽  
Antigen Antibody ◽  
Mouse Peritoneal Macrophages

Complement was found to stimulate markedly the ingestion of soluble antigen-antibody complexes by mouse peritoneal macrophages. This was shown indirectly by measuring the release of degradation products when the complexes were labeled with 125I, or directly when the antigen, that was human transferrin, was labeled with 59Fe. In this case, the metal which was released from human transferrin inside the cells was not excreted, and its accumulation in the macrophages was a direct index of the uptake of immune complexes. The decay of radioactivity in macrophages after ingestion of 125I-labeled complexes was similar when they were taken up with or without complement, indicating that complement acts primarily on ingestion and not on digestion or excretion. The ingestion of complexes was morphologically confirmed using fluorescein-labeled antigen in the immune complexes. The opsonic effect of complement was also observed with IgM aggregates indicating that soluble complexes can be ingested through complement receptors without involvement of Fc-receptors, as required for particulate antigen-antibody complexes.

scholarly journals ONTOGENY OF B LYMPHOCYTES

1974 ◽  
Vol 139 (5) ◽  
pp. 1125-1141 ◽  
Author(s):  
Michael C. Gelfand ◽  
Gerald J. Elfenbein ◽  
Michael M. Frank ◽  
William E. Paul
Keyword(s):  
B Lymphocytes ◽  
B Lymphocyte ◽  
Genetic Difference ◽  
Backcross Progeny ◽  
Soluble Antigen ◽  
B Cell Differentiation ◽  
Adult Mice ◽  
The Difference ◽  
Antigen Antibody ◽  
Akr Mice

Many bursa-equivalent (B) lymphocytes of adult mice bear surface Ig and receptors for C3. The frequency of Ig-bearing cells increases rapidly immediately after birth, but these cells lack complement (C) receptors. Lymphocytes bearing C receptors are not found in the spleens of BALB/c, DBA/2, and C57BL/6 mice until 2 wk of age and do not attain substantial numbers until 3–4 wk of age. In AKR mice, a lag between appearance of Ig-bearing and complement receptor lymphocytes (CRL) is also observed but it is of much shorter duration. AKR mice have a frequency of CRL at 2 wk of age of 28% in comparison to a frequency of 4.8% for DBA/2 mice. The difference in frequency between young and adult mice and between "low" and "high CRL" strains cannot be explained by a nonspecific inability to form rosettes as similar results are obtained with soluble antigen-antibody-complement complexes. Analysis of CRL frequency in (AKR x DBA/2)F1 mice and F1 x parental backcross progeny suggests that two independent genes control the rate of appearance of CRL. Furthermore, the genetic difference in the ontogeny of CRL is recapitulated in the repopulation of the B-lymphocyte line in adult-irradiated mice restored with syngeneic bone marrow. Thus, the "CRL genes" described here appear to control B-cell differentiation throughout life.

scholarly journals Interactions between lymphocyte membrane molecules. I. Interaction between B lymphocyte surface IgM and Fc IgG receptors requires ligand occupancy of both receptors.

1981 ◽  
Vol 153 (5) ◽  
pp. 1329-1343 ◽  
Author(s):  
H B Dickler ◽  
M T Kubicek
Keyword(s):  
B Lymphocyte ◽  
Surface Membrane ◽  
Specific Interaction ◽  
Normal Serum ◽  
Membrane Receptors ◽  
Soluble Antigen ◽  
Lymphocyte Surface ◽  
Igg Receptors ◽  
Antigen Antibody

The independent B lymphocyte surface membrane receptors IgM and Fc IgG receptors were evaluated for interactions using immunoflourescence. Ligand [F(ab')2 anti-mu]-induced capping of surface IgM resulted in capping of Fc IgG receptors only if the latter were occupied during the capping process by: (a) soluble antigen-antibody complexes that themselves provided insufficient cross-linking to result in capping; or (b) monomeric IgG at physiologic concentrations (or less) either purified or as normal serum. Ligand-induced capping of Fc IgG receptors did not result in capping of surface IgM occupied by monomeric F(ab') anti-mu. Control experiments showed that ligand binding to or capping of only one of these two receptors has no effect on the other, and that there were no cross-reactions. The interaction appears specific in that ligand-induced capping of surface IgM did not induce capping of ligand-occupied surface IgD or I-A antigens. Thus, there appears to be a specific interaction between ligand-bound surface IgM and ligand-bound Fc IgG receptors on the B lymphocyte surface. The results also indicate that binding of monomeric IgG produces a reversible alteration in the Fc IgG receptor leading to association with ligand-bound surface IgM. Because Fc IgG receptors are continuously exposed to monomeric IgG in vivo, these results suggest that whenever surface IgM is involved in a B lymphocyte response to an immunologic stimulus, the Fc IgG receptor is also involved.

scholarly journals Monoclonal anti-light chain idiotype as a tumor-specific probe for human neoplastic B lymphocytes

Blood ◽  
1987 ◽  
Vol 69 (3) ◽  
pp. 919-923 ◽  
Author(s):  
M Wrightham ◽  
AL Tutt ◽  
MJ Glennie ◽  
TJ Hamblin ◽  
GT Stevenson ◽  
...  
Keyword(s):  
B Cell ◽  
Tumor Cells ◽  
B Lymphocytes ◽  
Light Chain ◽  
Normal Serum ◽  
Lymphocytic Leukemia ◽  
Light Chains ◽  
Specific Probe ◽  
Tonsillar Cells ◽  
Binding Curves

Abstract Tumor cells from patients with B cell neoplasms often secrete small amounts of free monoclonal light chains that can be found in the urine. Such tumor-derived light chains of the lambda type from a patient with typical chronic lymphocytic leukemia have been used to raise mouse monoclonal antibodies (MoAbs). A hybridoma-secreting antibody that recognized the idiotypic lambda chain but not normal lambda chains by a preliminary screen but which also reacted with idiotypic IgM from the patient's tumor cells was selected. This MoAb in fact recognized 1 in 20 X 10(3) molecules of pooled normal lambda chains, thus establishing its specificity for a private idiotypic determinant. It failed to give a detectable reaction with normal IgM, normal serum, or a panel of IgM paraproteins. The antibody bound to the patient's neoplastic B cells but not to normal tonsillar cells. The site of binding of the antibody to idiotypic IgM is clearly separate from that of another MoAb specific for idiotypic determinants on heavy plus light chains, since the two showed additive binding curves. The determinant also appeared to be less available in dimeric lambda chains than in monomeric lambda chains or in idiotypic IgM. Antibodies to idiotypic determinants on light chains show some technical advantages and should be useful for monitoring and possibly treating B cell tumors, either alone or together with the more conventional anti-idiotypic antibodies that usually recognize the heavy and light chain combination.

scholarly journals Exaptation of Retroviral Syncytin for Development of Syncytialized Placenta, Its Limited Homology to the SARS-CoV-2 Spike Protein and Arguments against Disturbing Narrative in the Context of COVID-19 Vaccination

Biology ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 238
Author(s):  
Malgorzata Kloc ◽  
Ahmed Uosef ◽  
Jacek Z. Kubiak ◽  
Rafik M. Ghobrial
Keyword(s):  
Cell Membrane ◽  
Host Cell ◽  
Envelope Glycoprotein ◽  
Mammalian Species ◽  
Viral Envelope ◽  
Spike Protein ◽  
Mammalian Evolution ◽  
Trophoblast Cells ◽  
Host Cell Membrane ◽  
Uterine Endometrium

Human placenta formation relies on the interaction between fused trophoblast cells of the embryo with uterine endometrium. The fusion between trophoblast cells, first into cytotrophoblast and then into syncytiotrophoblast, is facilitated by the fusogenic protein syncytin. Syncytin derives from an envelope glycoprotein (ENV) of retroviral origin. In exogenous retroviruses, the envelope glycoproteins coded by env genes allow fusion of the viral envelope with the host cell membrane and entry of the virus into a host cell. During mammalian evolution, the env genes have been repeatedly, and independently, captured by various mammalian species to facilitate the formation of the placenta. Such a shift in the function of a gene, or a trait, for a different purpose during evolution is called an exaptation (co-option). We discuss the structure and origin of the placenta, the fusogenic and non-fusogenic functions of syncytin, and the mechanism of cell fusion. We also comment on an alleged danger of the COVID-19 vaccine based on the presupposed similarity between syncytin and the SARS-CoV-2 spike protein.

scholarly journals Monoclonal anti-light chain idiotype as a tumor-specific probe for human neoplastic B lymphocytes

Blood ◽  
1987 ◽  
Vol 69 (3) ◽  
pp. 919-923
Author(s):  
M Wrightham ◽  
AL Tutt ◽  
MJ Glennie ◽  
TJ Hamblin ◽  
GT Stevenson ◽  
...  
Keyword(s):  
B Cell ◽  
Tumor Cells ◽  
B Lymphocytes ◽  
Light Chain ◽  
Normal Serum ◽  
Lymphocytic Leukemia ◽  
Light Chains ◽  
Specific Probe ◽  
Tonsillar Cells ◽  
Binding Curves

Tumor cells from patients with B cell neoplasms often secrete small amounts of free monoclonal light chains that can be found in the urine. Such tumor-derived light chains of the lambda type from a patient with typical chronic lymphocytic leukemia have been used to raise mouse monoclonal antibodies (MoAbs). A hybridoma-secreting antibody that recognized the idiotypic lambda chain but not normal lambda chains by a preliminary screen but which also reacted with idiotypic IgM from the patient's tumor cells was selected. This MoAb in fact recognized 1 in 20 X 10(3) molecules of pooled normal lambda chains, thus establishing its specificity for a private idiotypic determinant. It failed to give a detectable reaction with normal IgM, normal serum, or a panel of IgM paraproteins. The antibody bound to the patient's neoplastic B cells but not to normal tonsillar cells. The site of binding of the antibody to idiotypic IgM is clearly separate from that of another MoAb specific for idiotypic determinants on heavy plus light chains, since the two showed additive binding curves. The determinant also appeared to be less available in dimeric lambda chains than in monomeric lambda chains or in idiotypic IgM. Antibodies to idiotypic determinants on light chains show some technical advantages and should be useful for monitoring and possibly treating B cell tumors, either alone or together with the more conventional anti-idiotypic antibodies that usually recognize the heavy and light chain combination.

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