The latter approach has the advantage of being able to validate peptide selection by assessing in vitro recall responses using peripheral blood mononuclear cells (PBMC) from normal healthy donors. While a broad range of

potential universal epitopes have Selleck BMN-673 been identified for both TT and DT [3], [4], [5], [6] and [7], a considerable amount of work has focused on TT830–844[8], [9] and [10]. Experimental evidence suggests that TT830–844 can be presented by up to ten different MHC class II alleles [3] and [6], although this has been disputed [11]. TT830–844 has been used as a helper peptide in various animal species including mice [12], [13] and [14], rats [15], rabbits [16] and rhesus macaques [17]. The predominant focus has been on using a helper peptide to improve a cytotoxic T lymphocyte (CTL) response for treating viruses and cancer [13], [14] and [15], rather than for enhancement of humoral immunity. Angiogenesis inhibitor In one primate study, a CTL response was induced to simian immunodeficiency virus peptides from Nef and Gag proteins [17]. However, only two of eight primates demonstrated a proliferative response to the peptide. Helper peptides have been used in several clinical studies, again primarily focusing on inducing CTL responses for the treatment of human viruses or cancer. TT830–844

has been tested in vaccines to induce CTL responses for treatment of chronic hepatitis B virus [18] and human immunodeficiency virus infection before [19], [20] and [21]. In addition, the helper peptide has been used to enhance CTL responses for the treatment of melanoma [22] and [23]. Those publications demonstrating recall response to TT830–844 report an average range of 60–75% of subjects responding [18] and [22]. However, in one report 91% of patients that received an immunization containing MHC class I restricted melanoma peptides plus TT830–844 demonstrated a recall response to the helper peptide, but 18% that did not receive the helper peptide also responded, presumably due to previous immunization with TT [23]. We have rationally designed a fully synthetic nanoparticle-based vaccine against nicotine for smoking cessation. However neither the B cell antigen, nicotine

nor the nanoparticle polymer contain T cell epitopes needed to provide help for B cell differentiation and antibody affinity maturation. Here we describe a ‘universal’ memory CD4 helper peptide that was designed and included in synthetic nanoparticle vaccines to provide promiscuous binding to a broad range of the most common MHC class II alleles in order to provide CD4 T cell help for B cell maturation and antibody production. We hypothesized that inclusion of a dimeric CD4 helper memory peptide (TpD) containing both TT and DT epitopes linked by a cathepsin linkage site, would result in improved antibody responses. We demonstrate that all 20 of tested normal human blood donors generated an in vitro memory recall response to the chimeric peptide.