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Med Mycol. 1998 Apr;36(2):97-106.

The effects of Malassezia on pro-inflammatory cytokine production by human peripheral blood mononuclear cells in vitro.

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The Skin Research Centre, Department of Microbiology, University of Leeds, Leeds LS2 9JT, UK.


Malassezia spp., the causative agents of pityriasis versicolor, are members of the normal human cutaneous microflora. Utilizing a combination of both enzyme-linked immunosorbent assay (ELISA) and bioassay, we have investigated the ability of both formalin-preserved and viable Malassezia (serovars A, B and C) to modulate pro-inflammatory cytokine (IL-6, IL-1beta and TNF-alpha) release by human peripheral blood mononuclear cells (PBMNC) in vitro, over a 48-h co-incubation period. The results demonstrated that formalin-preserved Malassezia (serovars A, B and C) at mid-exponential phase were generally able to induce a pro-inflammatory cytokine response at a yeast cell to PBMNC ratio of 1:1. In addition, the results consistently demonstrated that at a yeast cell to PBMNC ratio of 20:1, formalin-preserved Malassezia, irrespective of serovar, growth phase or PBMNC donor, were capable of significantly (P<0.05) decreasing the release of both immunochemical IL-6 and IL-1beta plus bioactive IL-1beta and TNF-alpha below that of unstimulated culture medium control values. This was apparent following 24- and 48-h co-incubation times, where maximal cytokine production was detected after 24 h. Similar results were obtained for the effect of viable Malassezia on pro-inflammatory cytokine release by PBMNC. Our results suggest that a possible inhibitory component, present perhaps within the cell wall of Malassezia, was responsible for this depressive effect on pro-inflammatory cytokine production.

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