66821
Descripción
Fichas por becki_fernandes, actualizado hace más de 1 año
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Creado por becki_fernandes
hace más de 11 años
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| Pregunta | Respuesta |
| what happens in a T cell independent B-cell response? | triggered by non-protein antigens (e.g. bacteria), leads to antigen receptor cross linkage on the surface of B-cells. stimulates IgM only (no class switching) |
| what happens in a t cell dependent response? | protein antigen recognised by B cells, internalised and digested, act as APC and present on MHC II, detected by TH2 and signal for class switching |
| where do naive B cells enter lymph nodes? | high endothelial venules |
| what happens if a B cell encounters an antigen on its way to the LN follicle? | B cell detects its epitope and begins to proliferate forming a primary focus (can now interact with T helper cells) |
| what is formed whe the B cells leave the primary focus and enter a follicle?? | creates a germinal centre and secondary follicle |
| where do activated B cells migrate o whn they have matured to plasma cells | medullary cord and are secreted into efferent lymph |
| describe the stages of a primary antibody response | 1. 5-7 day delay before AB production starts (LAG) 2. clonal expansion and plasma cells formed, IgM in blood (LOG) 3. class switching to IgG 4. decline - some plasma cells undeo apoptosis, some remain long term as memory cells |
| explain how a secondary response differs | lag phase is shorter, antibody prsists, atains a higher concentration and IgG is predominant |
| what do naive b cells initially synthsise? | IgD or IgM |
| what signals B cells to rearrange constant genes? | cytokine signals from B cells |
| what is meant by a monoclonal response? | antibodies that only recognise one epitope of one antigen |
| what do antibodies in the serum test for? | exposure to the pathogen, response to vaccination and immune mediated disease |
| what does a ELISA detect? | prescence of an antibody or antigen |
| what triggers clonal expansion of B cells? | surface imunoglobulin receptors recognise antigenic epitopes on surface of pathogens |
| where do plasma cells synthesise AB's into? | efferent lymph then reach tissues via bloodstream |
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