5-Fluorouracil infusion reduces gut-associated lymphoid tissue cell number and mucosal immunoglobulin A levels

Anticancer drugs have been demonstrated to affect gut mucosal morphology and cause gastrointestinal symptoms. We hypothesized that even small doses of 5-fluorouracil (5-FU) would reduce gut-associated lymphoid tissue (GALT) mass and function.

Mice underwent IV cannulation and received continuous infusion of normal saline or 10 mg/kg of 5-FU for 5 days. GALT cell numbers, phenotypes, and mucosal immunoglobulin A (IgA) levels were measured.

During the infusion, there were no significant differences in food intake or body weight change between the 2 groups. Cell yields from the intraepithelial space and lamina propria of the small intestine were lower in the 5-FU than the control group. The lamina propria CD4/CD8 ratio was reduced in the 5-FU compared with the control group. Intestinal and respiratory tract IgA levels were lower in the 5-FU than in the control group.

A small dose of 5-FU reduces GALT cell number and mucosal IgA levels, regardless of food intake.