The aim of this investigation was to study the effect of polysaccharide capsule on the gene expression in dendritic cells (DC) during their interaction with Cryptococcus neoformans. To this end, we used an encapsulated virulent strain of C. neoformans and a cap59 gene-disrupted acapsular avirulent strain derived from the same genetic background. DC were exposed to encapsulated and acapsular C. neoformans strains for 4 h and 18 h, and their transcriptional profiles were analyzed using the Affymetrix mouse gene chip U74Av2. A large number of DC genes were up-regulated after treatment with the acapsular strain. In particular, we observed the up-regulation of the genes involved in DC maturation, such as cell surface receptors, cytokines, and chemokines (interleukin-12 [IL-12], IL-2, IL-1␣, IL-1, IL-6, IL-10, tumor necrosis factor alpha, CCR7, CCL17, CCL22, CCL3, CCL4, CCL7, and CXCL10), membrane proteins, and the genes involved in antigen processing and presentation as well as cell cycle or apoptosis. The chemokine gene expression data were confirmed by real-time reverse transcription-PCR, while the expression of cytokine genes was correlated with their secretion. A completely different pattern of gene expression was observed for DC treated with an encapsulated strain of C. neoformans. In particular, no significant induction was observed in the expression of the genes mentioned above. Moreover, a number of genes, such as those coding for chemokines, were downregulated. These results suggest that the polysaccharide capsule shrouding the cell wall of C. neoformans plays a fundamental role in inducing DC response, highlighting the molecular basis of the true nature of immune silencing exerted by capsular material.Cryptococcus neoformans is an opportunistic encapsulated yeast that causes pulmonary, cerebral, and disseminated infections primarily in patients with defective T-cell immunity, such as those with AIDS, hematological malignancies, and organ transplants (33). The polysaccharide capsule is a major virulence factor of C. neoformans, the concept of which was initially established by studying several acapsular mutants obtained by chemical mutagenesis. These acapsular strains were avirulent in mice, and they were readily ingested by phagocytes, but their ingestion could be inhibited by the addition of purified polysaccharide (3). The effect of the C. neoformans polysaccharide capsule on the host cells can be summarized as follows: it interferes with phagocytosis, blocks the recruitment of inflammatory cells, increases costimulatory molecules, suppresses the delayed-type-hypersensitivity response, and reduces the antibody production in response to fungal infection (11,43).Dendritic cells (DC) are professional antigen-presenting cells that can initiate the innate and adaptive immune response against invading pathogens, thus enabling the decoding of microbe-associated information which then results in qualitatively different adaptive T-helper responses in vitro and in vivo (2, 8).Mouse DC internalize C. neoformans cel...