logo

BioFlix: Adaptive Defenses: B cells and Humoral Immunity

by Pearson
18 views
Was this helpful ?
0
Adaptive defenses help to control the current infection but also provide immunity against future infections by the same rhinovirus they are carried out by two types of lymphocytes B-cells and T-cells Immature B-cells conduct surveillance in the lymph nodes using B-cell receptors or BCR to recognize only one specific epitope The BCR on the left does not recognize the rhinovirus but the BCR on the right does and this B-cell is selected for activation in a step called clonal selection The selected B-cell takes in the rhinovirus, degrades it and presents the rhinovirus epitope with its MHC2 Our mature helper T-cell recognize the rhinovirus epitope with its TCR and the MHC2 with its CD4 Then the helper T-cell secretes chemical messengers known as cytokines that activate the B-cell The B-cell proliferates and differentiates in a process called clonal expansion resulting in two types of cell Memory B-cells carry the memory of this pathogen for many years Plasma cells secrete antibodies that conduct surveillance for more rhinoviruses grouping them together so they are easy targets for phagocytes antibodies in the blood and tissue fluids seek out free rhinoviruses the antibodies neutralize the rhinovirus by binding to its surface molecules thus preventing attachment to host cells antibodies are humeral defenses that target free pathogens
Adaptive defenses help to control the current infection but also provide immunity against future infections by the same rhinovirus they are carried out by two types of lymphocytes B-cells and T-cells Immature B-cells conduct surveillance in the lymph nodes using B-cell receptors or BCR to recognize only one specific epitope The BCR on the left does not recognize the rhinovirus but the BCR on the right does and this B-cell is selected for activation in a step called clonal selection The selected B-cell takes in the rhinovirus, degrades it and presents the rhinovirus epitope with its MHC2 Our mature helper T-cell recognize the rhinovirus epitope with its TCR and the MHC2 with its CD4 Then the helper T-cell secretes chemical messengers known as cytokines that activate the B-cell The B-cell proliferates and differentiates in a process called clonal expansion resulting in two types of cell Memory B-cells carry the memory of this pathogen for many years Plasma cells secrete antibodies that conduct surveillance for more rhinoviruses grouping them together so they are easy targets for phagocytes antibodies in the blood and tissue fluids seek out free rhinoviruses the antibodies neutralize the rhinovirus by binding to its surface molecules thus preventing attachment to host cells antibodies are humeral defenses that target free pathogens