Real-time PCR in clinical practice: a powerful tool for evaluating Leishmania chagasi loads in naturally infected dogs

The performance of the less expensive SYBR-Green-based PCR assay, for quantifying Leishmania chagasi in smears of bone-marrow aspirates from naturally infected, mongrel dogs, was recently compared with that of a similar PCR based on TaqMan chemistry. Aspirates were obtained from 36 infected dogs and examined for parasites by direct examination, culture, and quantitative PCR (qPCR) using specific primers (based on the parasite's kinetoplast DNA), DNA extracted from a smear, and either the SYBR-Green or TaqMan chemistries. Every aspirate smear was found PCR-positive for L. chagasi (whether the assay employed SYBR Green or TaqMan) but only 74% of the aspirates were found positive by culture and only 33% by direct, microscopical examination. There was no evidence of PCR inhibition when the DNA was collected from smears, and the parasite loads estimated using the SYBR-Green PCR were almost identical to those estimated using the TaqMan PCR (r=0.99). As a method for quantifying parasite loads in dogs infected with L. chagasi (and, probably, other mammals infected with other leishmanial parasites), PCR based on SYBR Green may therefore be an appropriate and inexpensive alternative to PCR based on TaqMan, and a reliable clinical tool.

Phase I trial of DNA-hsp65 immunotherapy for advanced squamous cell carcinoma of the head and neck

Considering that mycobacterial heat-shock protein 65 (hsp65) gene transfer can elicit a profound antitumoral effect, this study aimed to establish the safety, maximum-tolerated dose (MTD) and preliminary efficacy of DNA-hsp65 immunotherapy in patients with advanced head and neck squamous cell carcinoma (HNSCC). For this purpose, 21 patients with unresectable and recurrent HNSCC were studied. Each patient received three ultrasound-guided injections at 21-day intervals of: 150, 600 or 400 microg of DNA-hsp65. Toxicity was graded according to CTCAE directions. Tumor volume was measured before and after treatment using computed tomography scan. The evaluation included tumor mass variation, delayed-type hypersensitivity response and spontaneous peripheral blood mononuclear cell proliferation before and after treatment. The MTD was 400 microg per dose. DNA-hsp65 immunotherapy was well tolerated with moderate pain, edema and infections as the most frequent adverse effects. None of the patients showed clinical or laboratory alterations compatible with autoimmune reactions. Partial response was observed in 4 out of 14 patients who completed treatment, 2 of which are still alive more than 3 years after the completion of the trial. Therefore, DNA-hsp65 immunotherapy is a feasible and safe approach at the dose of 400 microg per injection in patients with HNSCC refractory to standard treatment. Further studies in a larger number of patients are needed to confirm the efficacy of this novel strategy.

CD4+CD25+Foxp3+ indirect alloreactive T cells from renal transplant patients suppress both the direct and indirect pathways of allorecognition

Alloreactive T cells recognize donor antigens by two routes: direct and indirect pathways of allorecognition. Although the direct pathway is reported to be dominant in allograft rejection, indirect allorecognition also plays an important role. Indirect alloreactivity is also observed in renal transplant patients irrespective of rejection. Previously we showed a predominance of interleukin (IL)-10 induced by indirect allorecognition of donor human leucocyte antigen (HLA)-DR peptides, suggesting the existence of indirect alloreactive T cells displaying regulatory activity. In the present work, our objective was to characterize these regulatory T cells. We detected indirect alloproliferation of peripheral blood mononuclear cells (PBMC) from renal transplant patients, induced by donor HLA-DR peptides, dependent on IL-4 or IL-10, suggesting regulatory activity as part of the alloreactive T-cell repertoire. PBMC-derived indirect alloreactive T-cell lines were established and produced both inflammatory and regulatory cytokines. We showed that two of these T-cell lines which were able to inhibit both direct and indirect alloproliferation of another T-cell line from the same patient presented a CD4(+)CD25(+)Foxp3(+) T-cell population. These data support the idea that indirect alloreactive T cells may also have regulatory activity and may contribute to the maintenance of the human renal allograft.