Fungal capsular polysaccharide and T-cell suppression: the hidden nature of poor immunogenicity.

Many capsular polysaccharide antigens are generally considered to be classic T-cell independent antigens that stimulate humoral response. This response is poor and short lived due to the absence of T-cell involvement. Recent emerging evidence suggests that fungal capsular polysaccharides may negatively affect T-cell response. This effect is indirectly mediated by antigen-presenting cells that sense microbial polysaccharides and manage T-cell response. This review will revisit the role of the cryptococcal capsular polysaccharide as a nonconventional regulator of natural and adaptive immune response, revealing the hidden nature of its poor immunogenicity and novel opportunities for the biomedical exploitation of this nontoxic compound.