Abstract
In order to assess immune responses during HIV‐1 therapeutic immunization, a large number of blood mononuclear cells (PBMC) are needed. Clinical tolerance and safety, as well as changes in immunological and virological parameters, were assessed, following leukapheresis in HIV‐1 infected subjects with CD4^+^ cell count >200 × 10^6^/l. PBMC were collected using a Fenwal CS3000 cell separator in 29 subjects with mean CD4^+^ cell counts of 503 × 10^6^/l (range 172–1,119) and viral load of 2.5 log~10~ copies/ml (range <1.7–5.4). Twenty‐four (83%) subjects were on antiretroviral therapy while 5 (17%) were untreated. The blood volume processed was 7 L over a period of 3 hours. A mean value (± standard error) of 82 ± 26 × 10^9^/l lymphocytes was collected by a single apheresis in a mean volume of 200 ± 1.8 ml, containing 9.0 ± 1.3 × 10^9^/l CD4^+^ and 10.2 ± 1.3 × 10^9^/l CD8^+^ cells. The leukapheresis procedures were well tolerated and no immediate or delayed side effects were observed within 90 days of follow‐up. No changes from blood pre‐leukapheresis values were detected for white blood cells, lymphocytes, monocytes, CD8^+^, CD34^+^, naive and memory CD4^+^ cell counts immediately after, 1 h, 7 days, or within 90 days after leukapheresis. However, absolute CD4^+^ cell counts and percentage significantly increased from pre‐leukapheresis values after 1 h (530 ± 43 vs. 700 ± 75 cell × 10^6^/l; 32.6 ± 1.6 vs. 36.9 ± 1.9%; P < 0.001 for both paired t‐tests) before returning to pre‐leukapheresis levels on day 7. No significant changes in viral load from pre‐leukapheresis levels in treated or untreated subjects were detected at any time points. We conclude that leukapheresis in HIV‐1 infected subjects with CD4^+^ cell counts >200 × 10^6^/l is safe and induces a transient increase in the absolute and percentage of CD4^+^ cell count without enhancing viral replication. J. Clin. Apheresis 18:55–60, 2003. © 2003 Wiley‐Liss, Inc.