CROI 2015 Program and Abstracts

Abstract Listing

Poster Abstracts

Conclusions: To our knowledge, this alteration of Blimp-1 expression on activated memory B cells in patients with HIV-1 infection has not been described before. We propose to further investigate the hypothesis whether down-regulation of Blimp-1 expression on activated memory B cells in patients with HIV-1 infection leads to uncontrolled differentiation into antibody secreting cells and consequently to an impaired production of neutralizing antibodies that has been described in HIV infection. 342 Similar or Higher Memory Responses to Influenza Vaccination in Aviremic HIV-infected Patients on Antiretroviral Therapy

Poster Abstracts

Zhenwu Luo; Lisa Martin; J. Michael Kilby; Wei Jiang Medical University of South Carolina, Charleston, SC, US

Background: Potential for recovery of antigen (Ag)-specific B cell functioning after long-term antiretroviral therapy (ART) in HIV-infected patients is not fully understood. Methods: We examined Ag-specific B cell responses to influenza (flu) vaccine in a cohort of 17 healthy controls and 28 ART-treated aviremic HIV+ patients who received vaccines last year and this year. Blood draws were taken at 0, 7, and 14 days after the latest vaccination. Number of Ag-specific antibody-secreting cells (ASC) were tested by ELISPOT in 0.5 million purified B cells at 0 and 7 days after vaccination. Flu vaccine-specific antibodies (IgM, IgG and IgA) were tested by ELISA in plasma. B cell apoptosis was assessed by flow cytometry. Results: The median percentages of CD4+ T cell among total CD3+ T cells were 60.32% (IQR 49.64% - 69.32%) and 45.12% (IQR 34.63% - 57.3%), and the median percentages of total CD19+ B cells among all lymphocytes were 7.31% (IQR 5.0% - 9.2%) and 9.2% (6.4% - 11.1%) in controls and patients pre-vaccination, respectively. The frequencies of naïve (CD27-), memory B cells (CD27+) and plasma cells (CD27+CD138+) among B cells were similar in controls and patients pre-vaccination (P > 0.05). Ex vivo, apoptosis of naïve B and plasma cells, but not memory B cells, was higher in patients than controls pre-vaccination (P < 0.05, Mann Whitney U test). Numbers of flu-specific ASC (IgM and IgA) were low to undetectable at all time points. Number of flu-specific ASC (IgG) in 0.5 million B cells were similar in HIV+ patients and controls before vaccination and at 7 days after vaccination (P > 0.05). Ag-specific IgG responses were not related to CD4+ T cell counts at any time point in both controls and patients. Consistently, patients had similar or higher levels of flu-specific IgM, IgG and IgA in plasma pre-vaccination, 7 days and 14 days post-vaccination compared to controls. Conclusions: Memory responses to influenza vaccination (TD antigen) are recovered in successful HIV virologic suppression after ART treatment even in patients with low CD4+ T cell counts, suggesting that recall responses are independent or much less dependent of CD4+ T cell help.

266

CROI 2015