Regulatory T-cells in alopecia areata.

BACKGROUND

Alopecia areata (AA) is believed to have an autoimmune mechanism in which the hair follicles are targeted by CD4+ and CD8+ lymphocytes. Studies investigating the autoimmune mechanism of other cutaneous diseases, including vitiligo, showed that Treg is a component of cutaneous immune privilege. Our study uses immunohistochemical staining in formalin-fixed, paraffin-embedded tissue to examine the percentage of CD4+ FoxP3+ , CD25+ FoxP3+ , and CD8+ FoxP3+ Treg in AA in human specimens.

METHODS

Immunohistochemical double staining for CD4+ FoxP3+ , CD25+ FoxP3+ , and CD8+ FoxP3+ was performed on 12 AA cases and 12 other autoimmune and non-autoimmune cutaneous diseases. The frequency of CD4+ FoxP3+ , CD25+ FoxP3+ , and CD8+  FoxP3+ Treg was counted and expressed as a percentage of total CD4+ , CD25+ , and CD8+ lymphocytes, respectively, in order to account for intersample inflammatory response variability.

RESULTS

There was a significant reduction in the mean frequency of CD4+  FoxP3+ and CD25+  FoxP3+ in AA when compared to other autoimmune and non-autoimmune cutaneous diseases.

CONCLUSION

Treg is significantly lower in AA when compared to other cutaneous diseases. Additionally, this immunohistochemical-staining protocol may be useful to evaluate Treg in formalin-fixed, paraffin-embedded specimens for other cutaneous diseases. Studies examining Treg in AA and other cutaneous diseases may have implications for future interventions.