title: Early induction of interleukin-12 by human monocytes exposed to Cryptococcus neoformans mannoproteins.
abstract: Interleukin-12 (IL-12) production by human monocytes stimulated with mannoproteins (MPs) of Cryptococcus neoformans was investigated. The results reported show that secreted or cell-associated MPs induce an early and significant production of IL-12. MPs show different capabilities to quantitatively affect IL-12 production; MP2, an 8. 2-kDa MP purified from the culture supernatant of C. neoformans, appears to be the most potent stimulator. Cytochalasin B inhibits both internalization and IL-12 induction by MP. In addition, a drastic reduction of IL-12 was observed when monocytes were cultured in the absence of normal human serum or treated with soluble mannan. Early production of IL-12 promotes early secretion of gamma interferon by T cells but does not influence the magnitude of the MP-induced lymphoproliferative response. Overall our results identify cryptococcal antigens responsible for rapid and potent induction of IL-12 in monocytes. MPs appear to regulate IL-12 secretion by internalization via the endocytic pathway and by interaction with monocyte receptors or serum factors.
authors.affiliation: Microbiology Section, Department of Experimental Medicine and Biochemical Sciences, University of Perugia, 06122 Perugia, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Pitzurra
authors.forename: R
authors.initials: R
authors.lastname: Cherniak
authors.forename: M
authors.initials: M
authors.lastname: Giammarioli
authors.forename: S
authors.initials: S
authors.lastname: Perito
authors.forename: F
authors.initials: F
authors.lastname: Bistoni
authors.forename: A
authors.initials: A
authors.lastname: Vecchiarelli
mesh_terms: D003455:Cryptococcus neoformans / Q000502:physiology*; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D018664:Interleukin-12 / Q000096:biosynthesis*; D008562:Membrane Glycoproteins / Q000502:physiology*; D009000:Monocytes / Q000378:metabolism*
chemical_list: D008562:Membrane Glycoproteins; C025363:mannoproteins; D018664:Interleukin-12; D007371:Interferon-gamma