Immunology of Diseases Associated withMalasseziaSpecies

Abstract

SUMMARY Malassezia species are members of the human cutaneous commensal flora, in addition to causing a wide range of cutaneous and systemic diseases in suitably predisposed individuals. Studies examining cellular and humoral immune responses specific to Malassezia species in patients with Malassezia-associated diseases and healthy controls have generally been unable to define significant differences in their immune response. The use of varied antigenic preparations and strains from different Malassezia classifications may partly be responsible for this, although these problems can now be overcome by using techniques based on recent work defining some important antigens and also a new taxonomy for the genus. The finding that the genus Malassezia is immunomodulatory is important in understanding its ability to cause disease. Stimulation of the reticuloendothelial system and activation of the complement cascade contrasts with its ability to suppress cytokine release and downregulate phagocytic uptake and killing. The lipid-rich layer around the yeast appears to be pivotal in this alteration of phenotype. Defining the nonspecific immune response to Malassezia species and the way in which the organisms modulate it may well be the key to understanding how Malassezia species can exist as both commensals and pathogens.

Malassezia nana sp. nov., a novel lipid-dependent yeast species isolated from animals

“…Malassezia species have been recognized as members of the microbiological flora of human and animal skin; they are also considered to be aetiological agents of pityriaris versicolor and Malassezia folliculitis in humans (Ashbee & Evans, 2002) and otitis externa in dogs. Malassezia pachydermatis and Malassezia sympodialis have been isolated from cats with otitis externa (Greene, 1998;Crespo et al, 2000), whilst Malassezia globosa, Malassezia furfur, Malassezia slooffiae and M. sympodialis have been isolated from cattle with otitis externa (Duarte et al, 1999(Duarte et al, , 2001).…”

Especies de Malassezia aisladas de pacientes con lesiones dermatológicas

“…New questions have been raised about the significance and relationships of the Malassezia species in clinical infections (1,4), this is due to factors such as the recent description of new species (2,21,22), the isolation of Malassezia as part of the microbial community of human skin rich in sebaceous glands (1,2,6,16), and the variability in colonization according to different age groups and sebaceous glands activity (15,19,23).…”

“…Many reports consider that M. globosa is the etiologic agent of pityriasis versicolor isolated from 25-97% of the cases (6,(9)(10)(11)(12)17,18). However, others have reported M. sympodialis as the most frequently isolated species (40-62.7%) (14,15).…”

Chemical Organization of the Cell Wall Polysaccharide Core of Malassezia restricta

“…Malassezia species are also known as opportunistic pathogens, being found associated with diverse dermatological pathologies including pityriasis versicolor, seborrheic dermatitis, atopic dermatitis, and folliculitis (1)(2)(3). Among these species, Malassezia restricta was revealed to be the most abundant Malassezia species on the scalp, neck, face, and ears of healthy volunteers (4,5).…”