Additionally, a previous study by Zhang and colleagues found that the percentage of BTLA+CD4+ T cells from healthy volunteers was much higher (~90% double positive); thus, future studies must be conducted with similar methods to those of Zhang and colleagues (that is, staining technique and a similar BTLA antibody clone) to determine whether SIRS patients that develop a subsequent infection have diminished BTLA expression with alternative staining methods such as these[32]. Here, CD4 is linked to infection.