Evaluation of IFN-γ Enzyme-linked Immunospot Assay (ELISPOT) as a First-line Test in the Diagnosis of Non-Immediate Hypersensitivity to Amoxicillin and Penicillin

The current diagnostic algorithm for beta-lactam allergy is based on skin and provocation tests, both of which carry a certain risk of inducing hypersensitivity reactions. Thus, non-invasive in vitro tests reliable enough to replace skin and provocation tests at least in a portion of patients are desirable. We aimed to verify the utility of IFN-γ ELISPOT as a first-line test in patients with suspected non-immediate hypersensitivity reaction to amoxicillin (AMX) and penicillin (PNC). The prospective observational study included 24 patients with recent, suspected non-immediate hypersensitivity reaction to AMX or PNC and 6 recently-exposed healthy subjects. In vitro tests were performed in all patients and healthy subjects: a) IFN-γ ELISPOT with PNC, AMX and amoxicillin plus clavulanic acid (AMX-CL); b) penicillin specific IgE; c) basophil activation test (BAT). Skin and provocation tests followed only in certain patients. IFN-γ ELISPOT results with PNC and AMX stimulation did not differ from the unstimulated condition. The highest IFN-γ responses to AMX-CL were close to previously published criteria in three patients; one of which had true hypersensitivity according to drug provocation tests. Five patients with confirmed hypersensitivity by skin tests showed no response to the culprit antibiotic on IFN-γ ELISPOT assay. Our results did not support the utility of IFN-γ ELISPOT in the diagnosis of mild, non-immediate hypersensitivity to amoxicillin and penicillin.

Vaccination with human papillomavirus type 16-derived peptides using a tattoo device

Tattooing has been shown to be very efficient at inducing immunity by vaccination with DNA vaccines. In this study, we examined the usability of tattooing for delivery of peptide vaccines. We compared tattooing with subcutaneous (s.c.) needle injection using peptides derived from human papillomavirus type 16 (HPV16) proteins. We observed that higher peptide-specific immune responses were elicited after vaccination with the simple peptides (E7(44-62) and E7(49-57)) and keyhole limpet hemocyanin-(KLH)-conjugated peptides (E7(49-57), L2(18-38) and L2(108-120)) with a tattoo device compared to s.c. inoculation. The administration of the synthetic oligonucleotide containing immunostimulatory CpG motifs (ODN1826) enhanced the immune responses developed after s.c. injection of some peptides (E7(44-62), KLH-conjugated L2(18-38) and L2(108-120)) to levels close to or even comparable to those after tattoo delivery of identical peptides with ODN1826. The highest efficacy of tattooing was observed in combination with ODN1826 for the vaccination with the less immunogenic E6(48-57) peptide and KLH-conjugated and non-conjugated E7(49-57) peptides which form the visible aggregates that could negatively influence the development of immune responses after s.c. injection but probably not after tattooing. In summary, we first evidenced that tattoo administration of peptide vaccines that might be useful in some cases efficiently induced both humoral and cell-mediated immune responses.

Enhancement of T cell-mediated and humoral immunity of beta-glucuronidase-based DNA vaccines against HPV16 E7 oncoprotein

Therapeutic DNA vaccines against oncogenic infection with human papillomavirus type 16 (HPV16) are mostly targeted against viral oncoproteins E7 and E6. To adapt the E7 oncoprotein for DNA immunization, we have previously reduced its oncogenicity by modification of the Rb-binding site and enhanced immunogenicity of the modified E7GGG gene by the fusion with the 5'-terminus of the gene encoding E. coli beta-glucuronidase (GUS). In this study, we attempted to improve immunogenicity of the GUS-based anti-E7 vaccines by increasing the steady-state level of fusion proteins. We fused deletion mutants of E7GGG and codon-optimized E7GGG with the 5'-terminus of GUS and unaltered E7GGG with the 3'-terminus of GUS. Furthermore, we mutated the initiation codon of the GUS gene in the E7GGG.GUS construct, as GUS alone was produced from this fusion gene. We found that only the fusion of E7GGG with the 3'-terminus of GUS (GUS.E7GGG) and deletion mutants of E7GGG with the 5'-terminus of GUS increased the steady-state level of fusion proteins in transfected human 293T cells. Analysis of immune reactions induced in mice by vaccination via a gene gun showed that the increased steady-state level of fusion proteins resulted in augmented production of E7-specific antibodies, but did not enhance cell-mediated anti-tumor immunity. Finally, we joined the signal sequence of the adenoviral E3 protein with GUS.E7GGG. This modification led to the predominant localization of the fusion protein in the endoplasmic reticulum and enhancement of CD8+ T-cell response, while antibody production was reduced. In conclusion, we found modifications of the E7GGG.GUS fusion gene that augmented either humoral or cell-mediated immune responses.