Protein sulphenic acid formation during CD4 + T cell activation

T cell receptor signalling requires a reduced cell surface protein environment and increased reactive oxygen species (ROS) inhibit activation. The main objective of this study was to identify sulphenated proteins on the membrane of T cells at rest, during activation and under oxidising conditions. Naive CD4 + T cells were activated using anti-CD3/CD28 antibodies in the presence or absence H 2 O 2 (20 µM) for 24 h. Activated CD4 + T cells in the presence of H 2 O 2 show a significant decrease in CD25 expression by twofold and IL-2 secretion (0.67±0.14ng/ml versus 1.16±0.09ng/ml). NAC (10 mM) did not reverse the effect of H 2 O 2 on IL-2 or CD25 after 24 h. CD4 + T cell-membrane proteins were isolated using MEM-PR kit after T cell activation with or without H 2 O 2 and sulphenated proteins were captured by a dimedone based technique. Captured proteins were identified by LC-MS/MS and the table below shows the number of sulphenated proteins; Activation alone did not affect the number of sulphenated membrane proteins. Activation in the presence of H2O2, which associated with lower intracellular calcium flux, show a reduction in number of sulphenated proteins possibly due to disulphide bond formation.