Page 285 - Hematology_ Basic Principles and Practice ( PDFDrive )

236 Part III Immunologic Basis of Hematology

APC

T cell

T cell activation
and expansion

Upregulation
of CD95

CD95
CD95
CD95
CD95
CD95
CD95
CD95
CD95 CD95 CD95 CD95
CD95
CD95
CD95
CD95
Interaction
CD95
of CD95
with CD95L
FADD
APC CD95L
Caspase activation
Apoptosis
CD95
cascade
B cell
CD95L CD95
CD95 CD95L
T cell
T cell
contraction

CD95
Surviving
memory cell
CD95
CD95
CD95 CD95

Fig. 21.11 CD95-DEPENDENT ACTIVATION-INDUCED CELL DEATH. After T-cell activation and
resultant expansion, T cells begin to upregulate the cell death receptor CD95. The ligand for CD95, CD95L,
is expressed on many cell types, including antigen-presenting cells (APCs), B cells, and the activated T cells
themselves. Binding of CD95 to CD95L triggers recruitment of the adapter protein Fas-activating via death
domain (FADD), resulting in activation of caspases and the induction of cell death through apoptosis. The
process of CD95 upregulation and apoptosis leads to contraction of activated T-cell populations.