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B and T cell Development and Antigen Recognition - Coggle Diagram
B and T cell Development and Antigen Recognition
Acquired immunity
Humoral cells - B cells
Cell mediated immunity
Secondary lymphoid tissue
B cells
Spleen
Mucosal tissue
Lymph nodes
T cells
Spleen
Lymph nodes
Tissues
Where do lymphocytes develop
Lymphoid Tissue
Primary lymphocytes are generated
Bone marrow
Thymus
Secondary: naïve/virgin lymphocytes reside
Lymph nodes, spleen
Mucosal lymphoid tissue (gut, nasal and respiratory tract
Primary lymphoid tissue
Haematopoietic stem cell - bone marrow (BM)
B cells - produced and mature in BM
T cells produced in BM and migrate to thymus and mature there
Mature T cells exit thymus. Enter circulation and travel through secondary lymphoid organs
T cell maturation in thymus
In the thymus, T cells are learned to tolerate self antigens and mature
The thymic epithelial cells presents self antigens to immature T cells
T cells with weak recognition of antigens are selected and released into circulation
Lymphocyte development and migration (journey)
B and T cells: are attracted to the secondary lymphoid organs via chemokine secretion
B cells expresses CXCR5 receptor and are attracted to CXCL13 chemokine produced from secondary lymphoid organs
T cells express CCRR7 receptor and are attracted to CCL 19/21 chemokines
T cells alter their receptor after antigen activation to migrate elsewhere
Compartmentalisation in lymph node
Lymphatic fluid
enters via afferent
exits via efferent
B cell zone (cortex)
T cell zone (paracortex)
enters lymph node via High Endothelial Venules
Antigens presented to T cells in the paracortex
Common themes in B and T cell development
Antigen dependent phase of development
occurs in primary lymphoid tissue
Virgin B and T cells
Secondary lymphoid tissue
Site of lymphocyte activation by the antigen
Lymphocytes constantly recirculate
Antigen dependent phase of development
Occurs in secondary lymphoid tissue after antigen stimulation
Effector cells
Progeny of virgin cells
Produce molecules that eliminate the antigen
Memory cells
Progeny of Ag stimulated cells
Encounter same Ag --> secondary immune response
