Immunochemical studies on L-rhamno-D-mannans of Sporothrix schenckii and related fungi by use of rabbit and human antisera.

Antisera were prepared in rabbits against the human pathogenic yeast Sporothrix schenckii (strain 1099.12) grown at two different temperatures (25 degrees and 37 degrees). Precipitation and inhibition data showed that the former serum had a specificity directed against alpha-L-Rhap-(1 yields 2)-alpha-L-Rhap-(1 yields 3)-D-Man-(1 yields determinants, whereas the latter had a broad specificity in which alpha-L-rhamnosyl or alpha-L-Rhap-(1 yields 3)-D-Man- was the immunodominant structure. These results are consistent with data on the structures of the L-rhamno-D-mannans isolated from the organism grown at the two different temperatures. Human sera from patients with sporotrichosis were shown to have different specificities resembling the specificities developed in the rabbits. The rabbit antisera were also used to examine the cross-reactivity with L-rhamno-D-mannans from species of the genus Ceratocystis, which is reputed to include the ascigerous (perfect) state of S. schenckii. Polysaccharides from four species of Ceratocystis grown at 25 degrees reacted with the antisera in a manner resembling that of the L-rhamno-D-mannan from S. schenckii grown at 37 degrees. This is in accord with earlier data that showed that only S. schenckii, of the species studied, produces a polysaccharide with large amounts of alpha-L-Rhap-(1 yields 2)-alpha-L-Rhap-(1 yields side-chains when grown at 25 degrees.