Serum immunoglobulin G subclasses in patients with ulcerative colitis and Crohn's disease of different disease activities.

BACKGROUND

Different concentrations of immunoglobulin G (IgG) subclass-producing cells in the mucosa of patients with ulcerative colitis and Crohn's disease have previously been described.

METHODS

To evaluate serum concentration of IgG subclasses as a tool for diagnosis and disease activity in chronic inflammatory bowel disease, we compared serum concentrations of IgG, IgA, IgM, and immunoglobulin subclasses IgG1, IgG2, IgG3, and IgG4 by means of the radial immunodiffusion technique in 66 patients with ulcerative colitis and in 68 patients with Crohn's disease of different clinical stages. Erythrocyte sedimentation rate, haemoglobin, and serum concentrations of albumin and orosomucoid were also determined.

RESULTS

The serum IgG1 concentration in patients with ulcerative colitis was 8.0 g/l significantly higher than in patients with Crohn's disease (6.8 g/l) (p < 0.005), whereas the serum IgG2 concentration in patients with Crohn's disease was 3.8 g/l, significantly increased compared with patients with ulcerative colitis (3.1 g/l) (p < 0.004). In patients with active ulcerative colitis the serum IgA level (2.03 g/l) was significantly lower than that in the patients with less active disease (2.74 g/l) (p < 0.03). No significant differences in serum concentrations of total IgG, IgG3, IgG4, and IgM were found between groups of patients with ulcerative colitis and Crohn's disease. The differences observed in IgG1, IgG2, and IgA concentrations, however, are small.

CONCLUSIONS

The serum concentrations of IgG, IgA, IgM, and IgG subclasses are of little value in the diagnostic procedures in individual patients and are not superior to conventional laboratory tests such as sedimentation rate and serum concentrations of orosomucoid and albumin.