Conditional deletion reveals a cell-autonomous requirement of SLP-76 for thymocyte selection

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• The SH2 domain-containing leukocyte phosphoprotein of 76 kD (SLP-76) is crucial for T cell development.
• Complete SLP-76 deficiency causes a block at the double-negative 3 (DN3) stage, limiting study of its role in later T cell stages.

Purpose of the Study:

• To investigate the function of SLP-76 in alphabeta T cell receptor (TCR) signal transduction in primary thymocytes and peripheral T cells.
• To overcome the developmental block by conditionally deleting SLP-76 after the DN3 stage.

Main Methods:

• Cre-loxP system to generate mice with conditional deletion of SLP-76.
• Analysis of thymocyte and peripheral T cell populations, including surface phenotype, cellularity, and calcium flux.

Main Results:

• Conditional SLP-76 deletion allowed development to the CD4+CD8+ double positive (DP) stage but impaired positive selection and activation-induced cell death.
• DP thymocytes lacking SLP-76 showed reduced cellularity and failed positive selection to single positive (SP) stages.
• Generated CD4+ SP thymocytes exhibited defective calcium flux upon alphabeta TCR stimulation.
• Peripheral T cells were reduced in number, lacked SLP-76, and displayed an abnormal surface phenotype.

Conclusions:

• SLP-76 is indispensable for signal transduction mediated by the mature alphabeta TCR in primary T lineage cells.
• This study provides the first direct evidence for SLP-76's requirement in alphabeta TCR signaling post-DN3 stage development.