scholarly journals Complement Receptor Type 1 Suppresses Human B Cell Functions in SLE Patients

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Mariann Kremlitzka ◽  
Bernadett Mácsik-Valent ◽  
Anna Polgár ◽  
Emese Kiss ◽  
Gyula Poór ◽  
...  
Keyword(s):  
B Cell ◽  
B Lymphocytes ◽  
Cell Activation ◽  
Receptor Type ◽  
Complement Receptor ◽  
B Cell Activation ◽  
Complement Receptor Type ◽  
Cell Functions ◽  
Inhibitory Capacity

Complement receptors (CRs) play an integral role in innate immunity and also function to initiate and shape the adaptive immune response. Our earlier results showed that complement receptor type 1 (CR1, CD35) is a potent inhibitor of the B cell receptor- (BCR-) induced functions of human B lymphocytes. Here we show that this inhibition occurs already at the initial steps of B cell activation since ligation of CR1 reduces the BCR-induced phosphorylation of key signaling molecules such as Syk and mitogen activated protein kinases (MAPKs). Furthermore, our data give evidence that although B lymphocytes of active systemic lupus erythematosus (SLE) patients express lower level of CR1, the inhibitory capacity of this complement receptor is still maintained and its ligand-induced clustering results in significant inhibition of the main B cell functions, similar to that found in the case of healthy individuals. Since we have found that reduced CR1 expression of SLE patients does not affect the inhibitory capacity of the receptor, our results further support the therapeutical potential of CD35 targeting the decrease of B cell activation and autoantibody production in autoimmune patients.

B cell activation leads to shedding of complement receptor type II (CR2/CD21)

2003 ◽  
Vol 33 (9) ◽  
pp. 2391-2397 ◽  
Author(s):  
Madhan Masilamani ◽  
Daniela Kassahn ◽  
Stefan Mikkat ◽  
Michael O. Glocker ◽  
Harald Illges
Keyword(s):  
B Cell ◽  
Cell Activation ◽  
Receptor Type ◽  
Complement Receptor ◽  
Type Ii ◽  
B Cell Activation ◽  
Complement Receptor Type

scholarly journals Analysis of C3-receptor activity on human B-lymphocytes and isolation of the complement receptor type 2 (CR2)

1984 ◽  
Vol 224 (1) ◽  
pp. 75-86 ◽  
Author(s):  
K J Micklem ◽  
R B Sim ◽  
E Sim
Keyword(s):  
Monoclonal Antibody ◽  
Affinity Chromatography ◽  
B Cell ◽  
B Lymphocytes ◽  
Receptor Type ◽  
Complement Receptor ◽  
Complement Receptor Type ◽  
Pure Protein

The rosetting of defined C3-fragment-coated sheep erythrocytes to B-cell-enriched tonsil lymphocytes was measured. The rosetting lymphocytes were homogeneous with respect to expression of C3b, iC3b and C3d receptors. Isolation of receptors for C3 fragments from surface-radioiodinated lymphocytes by affinity chromatography on immobilized C3u, iC3b and C3d,g produced two proteins with partially overlapping specificities. A protein of 240 000 Mr, recognized by the monoclonal antibody To5 and identified as CR1 (complement receptor type 1), had affinity for C3u and iC3b. A protein of 145 000 Mr, recognized by the monoclonal antibody B2, had affinity for all three C3 fragments. Inhibition of rosetting by antibodies to these proteins indicates that CR1 is responsible for C3b-mediated rosetting and that the 145000-Mr receptor (CR2) is responsible for C3d-mediated rosetting. Partial inhibition by both anti-CR1 and anti-CR2 antibodies of iC3b-mediated rosetting indicates that both receptors are involved in iC3b-mediated rosetting. No other protein appears to be involved in tonsil B-cell rosetting to C3-fragment-coated cells. A method for preparing CR2 from tonsil lymphocytes based on affinity chromatography on C3d,g-Sepharose has been developed. Forty tonsil pairs (2 × 10(10) B-cells) yield about 40 micrograms of pure protein equivalent to a purification of 6500-fold from a detergent extract.

scholarly journals Complement Receptor Type 1 (CD35) Mediates Inhibitory Signals in Human B Lymphocytes

2002 ◽  
Vol 168 (6) ◽  
pp. 2782-2788 ◽  
Author(s):  
Mihály Józsi ◽  
József Prechl ◽  
Zsuzsa Bajtay ◽  
Anna Erdei
Keyword(s):  
B Lymphocytes ◽  
Receptor Type ◽  
Complement Receptor ◽  
Complement Receptor Type ◽  
Complement Receptor Type 1

Intracellular Storage and Regulated Plasma Membrane Expression of Human Complement Receptor Type 1 in Rat Basophil Leukemia Cell Transfectants

Blood ◽  
1998 ◽  
Vol 92 (1) ◽  
pp. 300-309 ◽  
Author(s):  
Carolina Jost ◽  
Lloyd Klickstein ◽  
Erica Wetzler ◽  
Anoopa Kumar ◽  
Melvin Berger
Keyword(s):  
Plasma Membrane ◽  
Cell Activation ◽  
Leukemia Cell ◽  
Polymorphonuclear Neutrophils ◽  
Receptor Type ◽  
Leukemia Cell Line ◽  
Complement Receptor ◽  
Complement Receptor Type ◽  
Complement Receptor Type 1

Polymorphonuclear neutrophils (PMN) contain multiple distinct secretory compartments that are sequentially mobilized during cell activation. Complement receptor type 1 (CR1) is a marker for a readily mobilizable secretory vesicle compartment, which can undergo exocytic fusion with the plasma membrane independently of secretion of traditional granule contents. The basis for the formation of these distinct compartments is incompletely understood. Primary and secondary granules are generated directly from the Golgi complex during different stages of development of the cell, obviating the need for sorting signals for proper packaging of their constituents. To determine whether the secretory vesicles are formed in a similar manner, we studied a stable rat basophilic leukemia cell line (RBL-CR1) transfected with a plasmid containing the cDNA of human CR1 driven by a viral promoter. The CR1 was present primarily intracellularly in small vesicles resembling the CR1 storage pools in resting PMN. Activation of RBL-CR1 resulted in translocation of intracellular CR1 to the plasma membrane, with mobilization requirements different from those of the classical RBL granules. Thus, in RBL-CR1, continuously synthesized CR1 is stored and upregulated in much the same way as in PMN. This suggests that differential timing of gene expression is not essential for proper storage of CR1 and that other sorting mechanisms are involved, which can be studied in RBL-transfectants.

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