Saccharomyces cerevisiae (baker's yeast) may play an important part in the pathogenesis of
Crohn's disease. Because of this the levels of
IgG and
IgA antibodies against three S cerevisiae strains (NCYC 77, NCYC 79, and NCYC 1108) were assayed in 49 patients with
Crohn's disease, 43 with
ulcerative colitis, 14 with coeliac disease, and 21 healthy controls. Coded serum samples were tested by ELISA. Similar antibody patterns to all three strains were found.
IgG and
IgA antibody levels were significantly raised in patients with
Crohn's disease compared with healthy controls (p < 0.001 and p < 0.0001 respectively) and with
ulcerative colitis patients (p < 0.0001 and p < 0.0006 respectively). Raised
IgA, but not
IgG, yeast antibody levels were found in two patients with
Crohn's disease who were intolerant to yeast, but these values were similar to those in other patients without yeast intolerance. In
ulcerative colitis, both
IgG and
IgA levels were similar to normal controls. Patients with small bowel
Crohn's disease had significantly higher
IgG antibody levels than those with
colonic disease (p < 0.01). High levels of
IgG, but not
IgA, antibody were present in patients with coeliac disease, the antibody responses being indistinguishable from those found in
Crohn's disease. It is concluded that the presence of
IgG antibody to S cerevisiae is characteristic but not specific to
Crohn's disease. Although raised
IgA antibody levels are more frequently found in
Crohn's disease, their pathogenic importance remains to be established.