Immunohistochemical detection of IL-10 protein in tissues.

Positive cells contain brown pigment (ABC immunoperoxidase, hematoxylin counterstsain). (A) Lymph node from a patient with ALPS shows staining for IL-10 concentrated in the paracortex. Cells in the germinal center are not stained (× 100). (B) At higher power, intense positivity for IL-10 is observed in most of the interfollicular lymphocytes (× 400). (C) No signal for IL-10 is observed in a reactive lymph node from a normal control (× 100).