a) Direct tumor cell killing can be elicited by receptor agonist activity, such
ID: 70458 • Letter: A
Question
a) Direct tumor cell killing can be elicited by receptor agonist activity, such as an antibody binding to a tumor cell surface receptor and activating it, leading to apoptosis (represented by the mitochondrion). It can also be mediated by receptor antagonist activity, such as an antibody binding to a cell surface receptor and blocking dimerization, kinase activation and downstream signaling, leading to reduced proliferation and apoptosis. An antibody binding to an enzyme can lead to neutralization, signaling
abrogation and cell death, and conjugated antibodies can be used to deliver a payload (such as a drug, toxin, small interfering RNA or radioisotope) to a tumor cell.
b) Immune-mediated tumor cell killing can be carried out by the induction of phagocytosis; complement activation; antibody-dependent cellular cytotoxicity (ADCC); genetically modified T cells being targeted to the tumor by single-chain variable fragment (scFv); T cells being activated by antibody-mediated cross-presentation of antigen to dendritic cells; and inhibition of T cell inhibitory receptors, such as cytotoxic T lymphocyte-associated antigen 4 (CTLA4).
c) Vascular and stromal cell ablation can be induced by vasculature receptor antagonism or ligand trapping (not shown); stromal cell inhibition; delivery of a toxin to stromal cells; and delivery of a toxin to the vasculature (see the schematic illustration below).
The cell types known to mediate ADCC include [assess the following statements (115- 134) as either factually correct (= “true”) or incorrect (= “false”) in the given context]:
NOTE THAT IT SAYS IN THE GIVEN CONTEXT (if that matters)
115. Neurons
116. Neutrophils
117. Erythrocytes
118. Plasma cells
119. Keratinocytes
120. T lymphocytes
121. Paneth cells
122. Eosinophils
123. Enterocytes
124. B lymphocytes
125. Hepatocytes
126. NK cells
127. NK T cells
128. Macrophages
129. Fibrocytes
130. Myocytes
131. Monocytes
132. Endothelial cells
133. Dendritic cells
134. Osteoclasts
a Direct tumour cell killing b Immune-mediated tumour cell killing Phagocytosis Receptor Complement NK cell Receptor antagonist agonist Macrophage Antibody MACO Enzyme Fc receptor ADCC Tumour cell Conjugated antibody Granzyme and perforin -Toxin MHC and peptide C Vascular and stromal cell ablation CD35 or CD28 scFv Monoclonal antibodies Stromal cell Genetically modified T cell Anti-CTLA4 T cell Peptide Activation Conjugated antibodies Tumour Cross-presentation and T cell activation cell 0 Dendritic cell T cell Blood vesselExplanation / Answer
Antibody-dependent cell-mediated cytotoxicity is mediated by natural killer (NK) cells; macrophages, neutrophils and eosinophils, T LYMPHOCYTE, NK T cells, monocyte (macrophages) mediate ADCC.
Neurons, erythrocyte, plasma cells, keratinocyte, paneth cell, enterocyte , B lymphocyte, hepatocyte, fibrocyte, mycocyte, endothelial and osteoclasts have no role in ADCC
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