γδ T cells are more activated <i>in vivo</i>.

<p>Cholesterol depletion reduces the activated phenotype of γδ T cells. Cholesterol addition significantly increases the activation status of αβ T cells. (A–B) Staining of T cell activation markers shows more γδ T cell are in the activated state <i>in vivo</i>, comparing to αβ T cells. Splenocytes were isolated from C57BL/6J mice. T cell activation was identified by (A) CD44^hi CD62L⁻ and (B) CD69⁺ cells. Representative flow cytometric plots are shown on the left and the percentages of activated T cells are graphed on the right. Results were averaged from 6 mice, and shown in mean ± SEM. (C–E) Splenocytes from C57BL/6J were stimulated with T-activator CD3/CD28 beads for 4 hours in the presence or absence of MβCD to remove cholesterol from the plasma membrane. (C) Reduction of lipid raft levels in αβ and γδ T cells with cholesterol depletion. The reduction was more significant in γδ T cells, and the difference in lipid raft level became insignificant in αβ and γδ T cells after MβCD treatment. Lipid raft content was expressed in median florescent intensity of CT-B staining. (D) The percentage of CD44^hi CD62L⁻ cells was significantly lower in γδ T cells after 4 hours of cholesterol depletion. (E) The difference in expression of early activation marker CD69 was not statistically significant in both αβ or γδ T cells after MβCD treatment for 4 hours. However, the reduction of CD69 was significant in γδ T cells at 2 hours (inset) Results were averaged from 8 mice. Results were shown in mean ± SEM. (F) C57BL/6J splenocytes were stimulated with T-activator CD3/CD28 beads in the presence or absence of 10 and 20 µg/ml cholesterol for 4 hours. The percentage of CD44^hiCD62L⁻ cells was significantly increased in αβ T cells in a dose-dependent manner of cholesterol addition. On the other hand, activated γδ T cells were reduced with excess cholesterol. Results were averaged from 8 mice and shown in mean ± SEM. * P<0.05; ** P<0.01; *** P<0.001; ns not statistically significant.