CD4 and immunodeficiency disease: The CD4 cells were indeed very low (median; clinical model: 58 cells/μl; clonal model: 91 cells/μl) for X4-tropic patients, but also the R5-tropic patients had an advanced immunodeficiency (clinical model: 132 cells/μl; clonal model: 125/μl) when fpr10% was used.