Increased protein tyrosine kinase activity of the colonic mucosa in ulcerative colitis.

The protein tyrosine kinase (PTK) activity was measured in the inflamed colonic mucosa of 12 patients with ulcerative colitis and in the normal colonic mucosa of 12 control patients with colon cancer. The specific PTK activity in the particulate fraction obtained from ulcerative colitis mucosa was significantly increased compared with that of normal mucosa (5.10 +/- 0.60 pmol/min/mg versus 2.12 +/- 0.44 pmol/min/mg protein; p less than 0.05). Inflamed ulcerative colitis mucosa also showed a significantly higher total PTK activity in the particulate fraction than normal mucosa (2.60 +/- 0.42 pmol/min/g versus 0.91 +/- 0.16 pmol/min/g tissue; p less than 0.05). Mucosal samples from ulcerative colitis patients were divided into those with mild and those with severe inflammation on histologic examination (n = 6 each). The particulate PTK activity of severely inflamed mucosa was significantly higher than that of mildly inflamed mucosa (p less than 0.05). These results suggest that colonic inflammation in ulcerative colitis is associated with alterations in cellular PTK activity.