logicp_writings/health/Lymphocytes.md

Lymphocytes

Introduction

• T-Lymphocytes (Thymus): cellular
• B Lymphocytes (Bone Marrow): humoral
• NK (Natural Killer)
• Most undergo further antigen-mediated differention in lymphoid organs, but not a small subset of CD4+T
• CD4+T and CD8+T majorty of T-Lymphocytes

CD4T+

• Effector subtypes
• Activate Innate Immune, B, Cyto-T, and other cells
• Suppress immune reaction
• Subtypes: Th1, Th2, Th-17, Tfh, iTreg, Tr1, Th9

Lymphopoiesis

• Thymocytes from hematopoietic stem cell (marrow) come to thymus
• Thymus: primary lymphoid organ provides microenvironment of stromal cells, cytokines and chemokines to generate T-cells from thymocytes
• Gene rearrangement and thymocyte selection
• Affinity model (to peptide complex on Antigen-presenting cells APC):
  • low affinity thymocytes die
  • high affinity are destroyed
  • intermediate affinity are differentiated into CD4/8+
• CD4+: nTreg, NKT (also CD4-CD8-), mature-naive
• CD8+: MHC1b, MR1 mucosa-associated

Activation and Differentiation

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