Alpha 2-macroglobulin in patients with inflammatory bowel disease.

Alpha 2-macroglobulin (alpha 2-M) has been investigated in patients with ulcerative colitis and Crohn's disease and compared with normal control subjects. During an active phase of either disease, serum concentrations of alpha 2-M fall but no other relationship with clinical features was found. The proportion of circulating mononuclear cells bearing alpha 2-M on their surface in patients with inflammatory bowel disease did not differ from normal controls. Alpha 2-M was not detected in rectal tissue from either the patients or control subjects. The fall in alpha 2-M in patients with active disease was unexpected. Protein loss from the inflamed intestine is unlikely to be the cause and metabolic studies will be needed to elucidate synthetic and catabolic rates.