Principi di immunobiologia del trapianto ed attivazione della risposta immune

To achieve an effective immune response it is important that T cells can recognize a wide variety of non-self antigens; this allows for restrained immune activation and subsequent antigen-specific killing. This task is accomplished through the generation of a repertoire of T cells in a single individual with specificity for an enormous number of potential foreign antigens presented as peptides on the surface of major histocompatibility complex (MHC) molecules. Variations in MHC structure among individuals increase the variety of peptides that can be presented to T cells; this mechanism protects the species as a whole by ensuring adequate T-cell responses to a given foreign organism. Although slightly different, these MHC polymorphisms expressed in the donor kidney are recognized after kidney transplantation between non genetically-identical humans, and induce alloresponses that in the absence of immunosuppression result in rejection of the allograft. In this chapter, we review basic immunological principles important to the field of kidney transplantation.

Mhc polymorphisms fail to explain the heritability of phytohaemagglutinin-induced skin swelling in a wild passerine

Genetic estimates of the variability of immune responses are rarely examined in natural populations because of confounding environmental effects. As a result, and because of the difficulty of pinpointing the genetic determinants of immunity, no study has to our knowledge examined the contribution of specific genes to the heritability of an immune response in wild populations. We cross-fostered nestling house sparrows to disrupt the association between genetic and environmental effects and determine the heritability of the response to a classic immunological test, the phytohaemagglutinin (PHA)-induced skin swelling. We detected significant heritability estimates of the response to PHA, of body mass and tarsus length when nestlings were 5 and 10 days old. Variation at Mhc genes, however, did not explain a significant portion of the genetic variation of nestling swelling to PHA. Our results suggest that while PHA-induced swelling is influenced by the nest of origin, the importance of additive genetic variation relative to non-additive genetic variation and the genetic factors that influence the former in wild populations still need to be identified for this trait.