Antibody interactivity may thwart immunity to invasive infection.

2002 DEC 4 - (NewsRx.com & NewsRx.net) -- Some antibodies to Candida albicans can act as a barrier against "the protective potential of immune serum," researchers in Italy say.

"Mice immunized with heat-inactivated, whole yeast-form cells (Y cells) of Candida albicans developed intense, specific, normal and cell-mediated immune responses. However, they were modestly protected against a lethal challenge by the fungus, and their sera did not confer passive protection upon nonimmunized animals," reported C. Bromuro and colleagues.

"Surprisingly," they continued, "this immune serum conferred an elevated degree of passive protection to normal and SCID mice when preadsorbed on whole C. albicans cells. After adsorption, no antibodies specific to mannoprotein (MP)-rich extracts or secretions were detected by indirect enzyme-linked immunosorbent assay and no serum reaction with the fungal cell surface was seen in immunofluorescence assays. However, this serum had totally preserved the level of other antibodies, in particular those reacting with beta-1,3 and beta-1,6 glucan (GG)."

"The hypothesis that anti-GG antibodies contributed to the passive protection was suggested by the following circumstantial evidence:

* mice immunized with C. albicans cells treated with dithiothreitol and protease (YDP cells), which exposed GG on their surfaces and generated anti-GG but not anti-MP antibodies, were substantially protected against a lethal fungus challenge;

* the sera, and their ...