Modulation of innate and adaptive cellular immunity relevant to HIV-1 vaccine design by seminal plasma.
Mucosal exposure to HIV-1 infection generally occurs in the presence of semen. Immunomodulation by seminal plasma is well described in the reproductive biology literature. Little is known, however, about the impact of seminal plasma on innate and adaptive anti-HIV-1 cellular immunity.



The study investigated the effects of seminal plasma on immune responses considered important for prophylactic HIV-1 vaccine development, namely innate and adaptive cellular immunity mediated by natural killer (NK) cells and T cells, respectively.



The ability of seminal plasma to modulate direct, antibody-dependent and cytokine-stimulated NK cell activation was assessed utilizing intracellular cytokine staining. Direct and antibody-dependent cellular cytotoxicity was assessed using lactate dehydrogenase release assays. The effects of seminal plasma on T-cell activation upon stimulation with staphylococcus enterotoxin B or HIV-1 Gag peptides were assessed by intracellular cytokine staining. The impact of seminal plasma on redirected cytolysis mediated by T cells was measured using lactate dehydrogenase release assays.



Both direct and antibody-dependent NK cell activation were dramatically impaired by the presence of either HIV-1-uninfected or HIV-1-infected seminal plasma in a dose-dependent manner. Additionally, seminal plasma suppressed both direct and antibody-dependent NK cell-mediated cytolysis, including anti-HIV-1 antibody-dependent cytolysis of gp120-pulsed CEM.NKr-CCR5 cells. Finally, seminal plasma attenuated both HIV-1 Gag-specific and staphylococcus enterotoxin B-induced CTL activation.



Semen contains potent immunosuppressors of both NK cell and CD8 T-cell-mediated anti-HIV-1 immune responses. This could impede attempts to provide vaccine-induced immunity to HIV-1.
aDepartment of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne bDepartment of Infectious Diseases, Melbourne Sexual Health Centre, Alfred Health, Central Clinical School, Monash University cARC Centre of Excellence in Convergent Bio-Nano Science and Technology, University of Melbourne, Melbourne, Victoria, Australia.
Kevin J
KJ
Selva
Stephen J
SJ
Kent
Matthew S
MS
Parsons
D016915:AIDS Vaccines / Q000276:immunology*; D056704:Adaptive Immunity; D016207:Cytokines / Q000032:analysis; D003601:Cytotoxicity Tests, Immunologic; D005260:Female; D006801:Humans; D007111:Immunity, Cellular; D007113:Immunity, Innate; D007155:Immunologic Factors / Q000378:metabolism*; D007694:Killer Cells, Natural / Q000276:immunology; D008297:Male; D012661:Semen / Q000378:metabolism*; D013194:Staining and Labeling; D013601:T-Lymphocytes / Q000276:immunology
D016915:AIDS Vaccines; D016207:Cytokines; D007155:Immunologic Factors