Changes in immunological and virological parameters in HIV-1 infected subjects following leukapheresis

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 × 10⁶/1. PBMC were collected using a Fenwal CS3000 cell separator in 29 subjects with mean CD4⁺ cell counts of 503 × 10⁶/1 (range 172-1,119) and viral load of 2.5 log₁₀ 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 × 10⁹/1 lymphocytes was collected by a single apheresis in a mean volume of 200 ± 1.8 ml, containing 9.0 ± 1.3 × 10⁹/1 CD4⁺ and 10.2 ± 1.3 × 10⁹/1 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 × 10⁶/1; 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 × 10⁶/1 is safe and induces a transient increase in the absolute and percentage of CD4⁺ cell count without enhancing viral replication.