Rm. Zancopeoliveira et al., EFFECTS OF HISTOPLASMIN-M ANTIGEN CHEMICAL AND ENZYMATIC DEGLYCOSYLATION ON CROSS-REACTIVITY IN THE ENZYME-LINKED IMMUNOELECTROTRANSFER BLOT METHOD, Clinical and diagnostic laboratory immunology, 1(4), 1994, pp. 390-393
The enzyme-linked immunoelectrotransfer blot (EITB) method was evaluat
ed as a suitable method for detecting antibodies against M antigen of
Histoplasma capsulatum by use of both glycosylated and deglycosylated
M protein of histoplasmin (HMIN). Sera from patients with histoplasmos
is, paracoccidioidomycosis, blastomycosis, coccidioidomycosis, and asp
ergillosis were tested by the EITB with glycosylated M protein of HMIN
. This assay demonstrated 100% sensitivity with histoplasmosis serum s
amples, all of which reacted with the 94-kDa glycoprotein (M antigen).
Although the EITB is highly sensitive, it is not specific for histopl
asmosis when glycosylated M protein is used as an antigen. A total of
81% of paracoccidioidomycosis, 25% of blastomycosis, 33% of coccidioid
omycosis, 73% of aspergillosis, and 16% of tuberculosis serum samples
cross-reacted with M protein of HMIN and yielded patterns indistinguis
hable from those obtained with histoplasmosis serum samples. The EITB
reactions with both untreated M antigen and M antigen altered by perio
date oxidation or by deglycosylation with endoglycosidases were compar
ed. Cross-reactions with heterologous sera in the EITB could be attrib
uted to periodate-sensitive carbohydrate epitopes, as reflected by the
increase in the test specificity from 46.1 to 91.2% after periodate t
reatment of M protein. The EITB for the detection of antibodies to M a
ntigen is a potential diagnostic test for histoplasmosis, provided tha
t periodate-treated M protein is used as an antigen.