Immunohistochemical detection (on frozen tissue sections) of CD40L+ cells within UNPC microenvironment. CD40L positivity is manifested as dot-like staining on isolated small lymphocytes. A. The figure shows a high content of CD40L+ lymphocytes, either intermingled with tumor cells or located around UNPC tumor nests, in a case (female, 37 years old) with high serum levels of sCD40L. B. The figure shows few CD40L+ lymphocytes in a case (male, 34 years old) with a low content of sCD40L. Original magnification ×250.