CD4 enumeration in HIV infected individuals

In the present study, two alternative methods for the enumeration of PB CD4+ lymphocytes are compared with conventional flow cytometry (FCM): the TRAX CD4 tm enzyme immunoassay test kit and a new method using an internal biological standard (liophilized lymphocytes) for the direct enumeration of total PB CD4+ T-cells. Both methods showed an overall high degree of correlation with conventional FCM. However, the TRAxCD4 tm enzyme immunoassay showed a significant overestimation of PB CD4+ T-cells that was not only due to monocyte-derived CD4 molecules and the use of liophilized lymphocytes as an internal biological standard showed a low level of correlation for patients displaying low CD4 counts.