'Human Leukocyte Antigen B*27' (subtypes B*2701-2724) is a class I surface antigen encoded by the B locus in the major histocompatibility complex (MHC) on chromosome 6 and presents microbial antigens to T-cells.

But, during an infection, they receive chemical signals-usually interferon gamma-which increases their production of MHC II molecules and which prepares them for presenting antigens.

The mechanism by which MHC class II molecules increase a host's susceptibility to autoimmune reactions in RHD is unknown, but it is likely related to the role HLA molecules play in presenting antigens to T cell receptors, thus triggering an immune response.

The B cell can present antigens to helper T cells.

IgG and IgM antibodies bind to these antigens to form complexes that activate the classical pathway of complement activation to eliminate cells presenting foreign antigens (which are usually, but not in this case, pathogens).

Epithelial cells can present antigens and stimulate immune cells, and these, in turn, can modulate epithelial cells through the release of soluble mediators.1 The contribution of epithelial cells to the formation of the inflammatory mediators is probably selective.

Most cells are capable of presenting antigens and activating the adaptive response.

For example, active microglia are the primary effectors of innate immunity and fulfill this role by phagocyting the proteins of dead neurons, presenting antigens at their surface, and producing a variety of pro-inflammatory cytokines and toxic molecules that compromise the survival of surrounding neurons which may be similarly damaged or infected.

Most simply, individual MHC alleles may be especially effective, or especially ineffective, at presenting antigens from particular infections, so that carrying one or two copies of a given MHC allele might predispose an infected individual to a more or less favorable disease outcome.

This contrasts with the role of other dendritic cells in presenting pathogen-derived antigens in order to activate specific anti-pathogen T-cell and B-cell responses.