Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Monoclonal antibodies to sheep erythrocytes (SRBC) have proved useful in identifying two Fc receptors on mouse macrophages, one for IgG2a, and one for IgG1 and IgG2b. We have used monoclonal IgG3 anti-SRBC to identify a third Fc receptor on mouse macrophages which binds IgG3 uniquely. This receptor is present on primary resident and thioglycolate-induced peritoneal macrophages and on some macrophage cell lines. The binding of IgG3-coated SRBC is inhibited by aggregated byt not monomeric IgG3, and not by IgG1, IgG2a, and IgG2b aggregates. It is unaffected by treating the macrophages with trypsin or cytochalasin B and occurs at both 4 degrees and 37 degrees C. IgG3, like all other IgG subclasses, mediates phagocytosis. We have also generated a variant macrophage line which bears the receptors for IgG1 and IgG2b and for IgG2a, but not for IgG3.
 ...
PMID:A new Fc receptor on mouse macrophages binding IgG3. 725 6

A human colon cancer cell line, HCT-8, is shown to be an appropriate target cell for study of natural killer (NK) activity in man. In parallel experiments, effector cell characteristics for NK and antibody-dependent cellular cytotoxicity (ADCC) were found to be vested in a single lymphocyte subpopulation, which bore receptors for the Fc fragment of IgG, but lacked other surface receptors. The effector cell failed to adhere to glass and was inactivated by exposure to 3500 rad x-irradiation. Cells forming rosettes with SRBC and cells bearing receptors for complement were inactive in both systems. A wide distribution of NK activity was noted among individuals that correlated with the distribution of effector cell activity in ADCC (r = 0.8). Preincubation of NK effector cells with antibody-coated ADCC target cells markedly reduced NK activity. Neuraminidase treatment of effector cells led to increased NK and diminished ADCC, while trypsin treatment led to reduced NK activity and showed no effect on ADCC. Thus, NK and ADCC effector cells are highly overlapping if not identical populations, but different structures on the cell membrane may mediate the two activities.
 ...
PMID:Natural killer activity of human lymphocytes against colon cancer cells. 735 60

Monoclonal IgG1 anti-SRBC has been used to study the binding of monomeric and aggregated IgG1 to Fc receptors on mouse macrophages. Aggregated IgG1 was found to bind to Fc receptors on two macrophage cell lines and on primary macrophages. It competes for binding with IgG2b and not IgG2a. Like the binding of IgG2b, the binding of IgG1 is unaltered at 4 degrees C and is insensitive to trypsin or cytochalasin B. Antigen-bound IgG1, like IgG2b and IgG2a, mediates phagocytosis. Variant macrophage cell lines selected for the loss of phagocytosis through the IgG2b receptor no longer phagocytize IgG1 bearing SRBC. Monomeric IgG1 did not bind to either macrophage lines or primary macrophages. We conclude from these experiments that antigen-activated IgG1 binds to the same receptor as IgG2b.
 ...
PMID:IgG1 and IgG2b share the Fc receptor on mouse macrophages. 739 72

Human red blood cells (RBC) have a well-defined lifespan of 120 days affected by many cellular parameters. The aim of the present study was to investigate through a functional assay the effect of some factors in the interaction of erythrocytes with monocytes: heat rigidification, equilibration at different pH and desialyzation. We also studied the interaction between stored RBC and peripheral blood monocytes with this functional erythrophagocytosis assay. Blood samples from 30 volunteer donors were investigated. 1) Senescent (Se) and Young (Y) RBC were obtained by differential centrifugation. 2) Erythrocyte suspensions: Aliquots of each sample were subjected to the following treatments: a) Rigidification by heat (RRBC), b) Equilibration at different pH (5.34, 6.30, 7.33, 9.20) and c) Desialyzation with neuraminidase and trypsin. The functional assay was performed incubating monocytes obtained by glass adherence with these suspensions of RBC. Whole blood samples (n = 20) were stored during different periods of time (0, 7, 14, 21, 28, 35 and 42 days). The erythrophagocytosis assay was performed during six weeks incubating isologous monocytes with RBC from every unit. Negative and positive controls were performed using non sensitized (NSRBC) and sensitized with IgG anti-RhD (SRBC) red cells. The percentage of active monocytes (AM) obtained were: 1) YRBC: 2.8 +/- 0.9 and SeRBC: 17.5 +/- 2.1; 2a) RRBC: 3.0 +/- 0.9; 2b) 10.9 +/- 0.9, 15.5 +/- 0.8, 3.1 +/- 1.0, 4.0 +/- 1.1; 2c) 11.1 +/- 1.4 and 3.9 +/- 1.0; SRBC 32.1 +/- 1.7 and NSRBC: 2.8 +/- 1.5. The % of AM with SeRBC was higher (p < 0.001) than those obtained with NSRBC. The data of AM with RRBC were significantly lower (p < 0.001) than those obtained with SeRBC and SBRC, indicatingthat heat rigidification of RBC does not increase phagocytosis by monocytes. The values of AM obtained from the suspensions of erythrocytes equilibrated at different pH indicate that the acidification of RBC increases the interaction with monocytes. The % AM with neuraminidase treated RBC was higher than those observed with YRBC and NSRBC (p < 0.001). No modifications were observed with trypsin treated RBC. These results suggest that the loss of sialic acid may be involved in the physiological phagocytosis. The values of AM of stored whole blood were: 2.3 +/- 1.3, 2.7 +/- 1.3, 4.4 +/- 1.6, 6.7 +/- 1.2, 9.6 +/- 1.0, 11.7 +/- 0.8 and 13.0 +/- 1.2. The results showed a significant increase in the % of AM as a function of the preservation time from 2,3 +/- 1,3 for the first day to 13,0 +/- 1,2 for the 42nd day (p < 0.001). The data obtained in this ex vivo model show a significant increase (p<0.001) in the phagocytosis of RBC equilibrated at low pH, desialinized (greater than 80%) with neuraminidase and stored for over 28 days. These factors would be involved in erythrocyte removal via phagocytosis during tissular homeostasis.
 ...
PMID:Senescent erythrocytes: factors affecting the aging of red blood cells. 1199 Apr 62


<< Previous 1 2 3 4