Monoclonal antibody specific to glucosylceramide found in pathogenic fungi

MONOCLONAL ANTIBODY SPECIFIC TO GLUCOSYLCERAMIDE FOUND IN PATHOGENIC FUNGI

TOLEDO MS, SUZUKI E, LEVERY SB¹, STRAUS AH AND TAKAHASHI HK

Department of Biochemistry, UNIFESP, 04023-900 São Paulo, SP, Brazil

1University of Georgia/Complex Carbohydrate Research Center, Athens, Ga, 30602, USA.

Presented by L.R. TRAVASSOS

An IgG2a monoclonal antibody (MoAb) anti-glucosylceramide was established and termed MEST-2. HPTLC immunostaining, and solid-phase radioimmunoassay showed that MEST-2 reacts with glucosylceramides (GlcCer) from yeast and mycelium forms of Paracoccidioides brasiliensis, Histoplasma capsulatum, and Sporothrix schenckii; from mycelium forms of Aspergillus fumigatus; and from yeast forms of Candida Albicans, Cryptococcus neoformans, Cryptococcus laurentii, and Cryptococcus albidus. Indirect immununofluorescence showed that MEST-2 reacts strongly with the surface of yeast forms of P. brasiliensis, H. capsulatum, S. schenckii. Weak staining of mycelial forms of P. brasiliensis and hyphae of A. fumigatus was also observed. The sugar specificity of MEST-2 was assessed by inhibition assays using six different methyl-glycosides, and MEST-2 binding to GlcCer of the different fungi was inhibited only by methyl-b-D-Glc (80%). The lack of reactivity of MEST-2 with Gaucher's spleen GlcCer led us to analyze other structural features, besides b-D-Glc, that would be of importance in the reactivity of MEST-2 with fungal GlcCer. Studies on the fine specificity of MEST-2 using GlcCer purified from different strains of Cryptococcus and soybean showed that the 2-hydroxy group of the fatty acids is critical in the interaction of MEST-2 with fungal GlcCer. On the other hand, the importance of D³ unsaturation of fatty acids, and the D⁴ unsaturation of the long chain base in the epitope recognized by MEST-2 were ruled out because soybean GlcCer, which presents the same rectivity of fungal GlcCer, does not present this structural feature. Also other structural features of fungal GlcCer such as the 9-methyl group and D⁸ unsaturation of the sphingosine, apparently do no interfere the interaction between MEST-2 and fungal GlcCer since these structures are located far from the immunodominant epitope b-D-Glc and are possibly located in the lipid bilayer of the cell membrane.

— ( September 14, 1999 ) .

* Supported by: FAPESP, CNPq, PRONEX and NIH.

Publication Dates

• Publication in this collection
  07 Aug 2000
• Date of issue
  Mar 2000