CD4 and prostate neoplasm: In addition, analysis of TILs from prostate tumor samples also shows populations of T regulatory cells (Tregs) that are self-tolerant and produce marked immune inhibition, namely, classical CD4+ Tregs (CD4+CD25+) and less frequent CD8+ Tregs (CD8+FoxP3+), revealing active immune suppression mechanisms within the PCa tumor microenvironment.142