PRODUCTION AND FUNCTION OF CYTOKINES IN NATURAL AND ACQUIRED-IMMUNITYTO CANDIDA-ALBICANS INFECTION

Host resistance against infections caused by the yeast Candida albican s is mediated predominantly by polymorphonuclear leukocytes and macrop hages. Antigens of Candida stimulate lymphocyte proliferation and cyto kine synthesis, and in both humans and mice, these cytokines enhance t he candidacidal functions of the phagocytic cells. In systemic candidi asis in mice, cytokine production has been found to be a function of t he CD4(+) T helper (Th) cells. The Th-1 subset of these cells, charact erized by the production of gamma interferon and interleukin-2, is ass ociated with macrophage activation and enhanced resistance against rei nfection, whereas the Th-2 subset, which produces interleukins-4, -6, and -10, is linked to the development of chronic disease. However, oth er models have generated divergent data. Mucosal infection generally e licits Th-1-type cytokine responses and protection from systemic chall enge, and identification of cytokine mRNA present in infected tissues of mice that develop mild or severe lesions does not show pure Th-1- o r Th-2-type responses. Furthermore, antigens of C. albicans, mannan in particular, can induce suppressor cells that modulate both specific a nd nonspecific cellular and humoral immune responses, and there is an emerging body of evidence that molecular mimicry may affect the effici ency of anti-Candida responses within defined genetic contexts.