CD molecules other cell surface molecules

• nonclassical antigen presentation of nonprocessed, lipid based molecule to T cells
• loading occurs during various stages of endosomal trafficking
• can be self/foreign peptides

• gamma, epsilon, delta, zeta
• expressed starting on DN T cells
• required for signal 1 of T cells
• analogous to T cell CD79 signal transduction

• Class II MHC restricted T cells
• targeted by HIV

Class 1 MHC restricted T cells

• lymphocyte homing receptors to site of inflammation
• addressin molecules: VCAM1, ICAM1 (CD54)

• tight binding to ICAM-1 (CD54) for adhesion
• expressed on leukocytes

• expressed on T cell and APCs
• binds to LFA (CD11, CD18)
• flu viruses also bind to nasopharynx ICAM1

• target naive T cell to 2ndary lymphoid tissues
• binds to CD34 or GlyCAM1 on HEV or MAdCAM1 on mucosal endothelium
• initiates lymphocyte rolling and LFA activation

• expressed on mucosal endothelium
• allows targeting of naive T cell by binding L-selectin

• chemokine receptor on naive T cells
• interacts with CCL21 on HEV to activate LFA1
• similar function as L-selectin, CXCR4

HEV surface molecule that interacts with CCR7 to upregulate LFA1 expression on lymphocytes so it can adhere tightly to ICAM and initiate diapedesis

• naive T cells have CD45RA
• effector T cells have CD45RO--> lose L-selectin, gain more VLA4 --> bind to VCAM1 and ICAM1 on target tissue endothelium

• chemokine receptor on T cells that are activated in mucosal immune system
• allows permenant homing to mucosal immune system

• expressed by skin homing T cells
• interacts with E-selectin on cutaneous endothelium

• cutaneous endothelial chemokine
• allows skin homing T cell targeting via CCR4 binding

• expressed on skin homing T cells
• interacts with CCL17 (endothelial chemokine)
• strengthens the CLA to E-selectin bond

• keratinocyte chemokine
• allows targeting of skin homing T cell via interaction with CCR10

• expressed on skin homing T cells
• binds to CCL27 on keratinocyte

• B cell coreceptors that amplify BCR signal
• complexes with CD81 on APC and T cells

• B cell surface molecule
• APC's CD32 binding downregulate B cell signal

• expressed by macrophages, granulocytes, platelets
• inhibits B cell activation via BCR pathway

• aka IL2 receptor
• autocrine growth signal released by T cell following signal 1 + 2

• signal 2 for B cells
• also expressed on APCs
• binds CD4L (CD154) from T cells

• aka Igαβ
• expressed on mature B cells
• signal transduction by B cell antigen receptor complex

• aka B7.1, B7.2
• B cell B7s costimulate T cells via CD28
• APC B7s inhibit activated T cells via CD152

• expressed on most CD4 and CD8 T cells
• activated by B cell CD80/CD86 (B7.1, B7.2) signals

• expressed on activated T cells
• binding to APC CD80 (B7.1/B7.2) inhibits T cell activity

activated by gram -ve bacteria LPS

activated by gram +ve bacteria lipoproteins, DAG

pattern recognition receptors: detects PAMPs

pathogen associated molecular patterns: are expressed on microbes

• mannose binding lectin
• an example of PRRs that recognize carbohydrates on microbes

• PRRs in cytosol of most cells
• recognize viral dsRNA--> trigger IRF3, IRF7 transcription factor activation --> type 1 interferon production

• allows activated T cells to egress from thymus/LN to periphery
• S1P1 blockers suppress immunity

targets viral dsRNA

targets viral ssRNA

targets viral DNA

targets bacterial flagellin

expressed by Th1 for after activation

• expressed by Th2 cells after activation
• targets Th2 to GC so it can activate B cell isotype class switching