Methods Fungal isolates and growth conditions Paracoccidioides brasiliensis strain Pb18 was provided by Dr Z.P. Camargo, São Paulo, SP, Brazil. Yeast and VX-770 mycelia forms of P. brasiliensis were grown at 37°C and 25°C, respectively, in PGY (peptone 5 g/L, glucose 15 g/L, yeast extract 5 g/L) using 2.5 L Fernbach flasks in a shaker at 100 rpm [10]. Histoplasma capsulatum strain 496 selleck from human pulmonary lesion [33] and Sporothrix schenckii strain 65 from human foot cutaneous lesion [22, 23], were kindly provided by Dr O. Gompertz, São Paulo, SP, Brazil. Yeast and mycelia forms of both fungi were grown in

Brain Heart Infusion (BHI) (37 g/L) at 37°C and 25°C, respectively. After 5-7 days both yeast and mycelia forms of the various fungi were inactivated with 0.1% of thimerosal, and after an additional 48 h the fungi were collected by filtration on Whatman n° 1 filter paper, except for yeast forms of S. schenckii and H. capsulatum, which were harvested by centrifugation at 5,200 × g for 20 minutes. Extraction

and purification of glycosphingolipids (GSLs) GSLs were extracted by homogenizing yeast or mycelia forms (~ 30 g) in an Omni-mixer (Sorvall Inc. Wilmington, DE), three times with 200 ml of isopropanol/hexane/water (IHW, 55:20:25, v/v/v, upper phase discarded), and twice with 200 ml of chloroform/methanol (CM, 2:1, v/v). The five extracts were pooled, dried on rotary evaporator, dialyzed against water and lyophilized. Neutral and acidic GSLs were separated in a DEAE-Sephadex A-25 column as described by Yu and Ledeen RG-7388 solubility dmso [34]. Fractions containing GIPCs, were assessed by HPTLC on silica gel 60 plates (E. selleck inhibitor Merck, Darmstadt, Germany) using solvent A: chloroform/methanol/CaCl2 0.02%, (60:40:9; v/v/v), and stained with orcinol/H2SO4. For preparative-scale HPTLC separated GSL bands were visualized under UV light after spraying

with primulin 0.01% in 80% aqueous acetone [35]. GSLs were isolated from silica gel scraped from the plates by repeated sonication in IHW, as described [36]. Production of hybridomas About 600 μg of GIPC Pb-2 purified from mycelia forms of P. brasiliensis were dissolved in 1.5 ml of distilled water and mixed with 1.5 mg of acid-treated heat-inactivated Salmonella minnesota. Aliquots (100 μl) of this suspension containing 40 μg of the antigen were used to immunize six weeks old BALB/c mice, by i.v. route, through the caudal vein once a week, over 4 weeks. After a rest period of 30 days, the immune response was boosted with 200 μl of the immunogenic complex. Three days later, the mice were sacrificed and their spleen removed. The lymphocytes were fused with NS-1 myeloma cells and placed in 96-well plates. Solid-phase RIA detected hybrids secreting immunoglobulins reacting with Pb-2. Only clones showing strong reactivity with Pb-2 of mycelia and yeast forms of P. brasiliensis were cloned by limited dilution as described [13, 24, 37].