Cholesterol-dependent plasma membrane order (L(o)) is critical for antigen-specific clonal expansion of CD4(+) T cells

Early “T cell activation” events are initiated within the lipid microenvironment of the plasma membrane. Role of lipid membrane order (L(o)) in spatiotemporal signaling through the antigen receptor in T cells is posited but remains unclear. We have examined the role of membrane order (L(o))/disorder (L(d)) in antigen specific CD4(+) T cell activation and clonal expansion by first creating membrane disorder, and then reconstituting membrane order by inserting cholesterol into the disordered plasma membrane. Significant revival of antigen specific CD4(+) T cell proliferative response was observed after reconstituting the disrupted membrane order with cholesterol. These reconstitution experiments illustrate Koch’s postulate by demonstrating that cholesterol-dependent membrane order (L(o)) is critical for responses generated by CD4(+) T cells and point to the importance of membrane order and lipid microenvironment in signaling through T cell membrane antigen receptors.