Among 655 men and women with HIV, CD4+ count at HAART initiation predicted subsequent recovery of this important immune system cell. Patients receiving HAART showed an improvement after 4 years of treatment and maintained these levels for the next two. The researchers note, however, that those who began treatment after their CD4+ levels fell below 350 cells/ul failed to recover to normal levels. To achieve better recovery, the authors suggest HAART therapy be initiated when the CD4+ cell count is greater than 350 cells/ul.Source
Moore, R.D. and Keruly, J.C. CD4+ cell count 6 years after commencement of highly active antiretroviral therapy in persons with sustained virologic suppression. Clinical Infectious Diseases 44(3):441-446, 2007