A continuous infusion of a minor histocompatibility antigen-immunodominant peptide induces a delay of male skin graft rejection.

We previously reported that an inhibition of antigen-specific Interferon-gamma release and cytotoxicity occurs after a continuous infusion of an HY immunodominant peptide although this treatment is not able to cause a significant delay of male skin grafts rejection. In vivo administration of high doses of an HY peptide, through mini-osmotic pumps, in naïve female mice was used to study the effects on the male skin grafts rejection. A continuous infusion of 1mg of an HY peptide induces a significant delay of male skin graft rejection. In vitro HY-specific Interferon-gamma release was inhibited adding peptide-specific suppressor cells: the ability to inhibit Interferon-gamma release was evident when two HY peptides were present on the same dendritic cells indicating that the suppressor cells exert "linked-suppression". The phenotype of the suppressor cells is CD8(+)CD28(-) and these cells express more CD62 ligand and FOXP3 than controls. Suppressor cells were able to cause a significant delay of rejection of male skin grafts when injected in naive female mice. The inhibitory effects of these suppressor cells seem to be due to the impairment of antigen presentation; down-regulation of B7 molecules on dendritic cells occurred. Taken all together, our data demonstrate that a continuous infusion of an immunodominant HY peptide induces a T CD8 suppressor subset able to inhibit immune responses to male tissues and cells.

FACIT collagen (1alpha-chain) is expressed by hemocytes and epidermis during the inflammatory response of the ascidian Ciona intestinalis.

Based on previous cloning and sequencing study, real-time PCR and in situ hybridization assays of the inflamed body wall of LPS-injected Ciona intestinalis showed the enhanced gene expression of a collagen with FACIT structural features (Ci-type IX-Col 1alpha-chain). By using specific antibodies raised against an opportunely chosen Ci-type IX-Col synthetic peptide, the fibroblast property of hemocytes challenged in vitro with LPS (at 4h) was displayed by flow cytometry, while immunocytochemistry identified hemocytes with large granules (morula cells) as collagen-producing cells. Hemocyte lysate supernatant analyzed in immunoblotting contained a 60 kDa band identifiable as 1alpha-chain-Ci-type IX-Col. Observations of body wall sections (immunohistochemistry method) supported the role of hemocytes and showed that epidermis expressed Ci-type IX-Col 1alpha-chain in the time course of the inflammatory reaction (within 24h). Transcript and protein were mainly found in the epidermis that outlined the proximal side of the tunic matrix (at 24h after LPS injection), in cells associated with the epidermis at 4 and 192 h. In conclusion, the C. intestinalis inflammatory response to LPS challenge appeared to be composed of a complex reaction set, and for the first time we showed in ascidians a granulation tissue with FACIT-collagen production that could participate in inflammation and wound healing. Like in vertebrates, C. intestinalis acute inflammatory reactions result in a regulated pattern of tissue repair with collagen expression during remodelling. Ci-type IX-Col could be involved in a network of non-fibril-forming collagens that participates in the organization of extracellular matrix and defense responses.

Anti-16-kilodalton mycobacterial protein immunoglobulin m levels in healthy but purified protein derivative-reactive children decrease after chemoprophylaxis.

Serum responses against Mycobacterium tuberculosis HSP16 were determined for children with tuberculosis (TB) and for healthy purified protein derivative (PPD)-positive and PPD-negative children. Immunoglobulin G (IgG) and IgM responses were higher for TB patients than for other groups. After chemotherapy, IgM and IgG responses decreased for TB patients and PPD-positive subjects. Monitoring of anti-M. tuberculosis HSP16 responses could assist in the management of pediatric TB.

ESAT-6 peptide recognition by bovine CD8+ lymphocytes of naturally infected cows in herds from southern Italy.

The aim of this study was to define epitopes of Mycobacterium bovis from ESAT-6 (early secretory antigen of 6 kDa) recognized by CD8+ T lymphocytes from cows naturally infected with Mycobacterium bovis. We found that bovine CD8+ T cells recognized 10 out of 11 ESAT-6 peptides tested.