IL13 and anaphylaxis: IL-4 and IL-13 have been reported to promote intestinal permeability.18,19,49,50 To investigate their individual roles, blocking mAbs to mouse IL-4 or IL-13, or IgG1 isotype control, were administered i.p. on days 16 and 17, intestinal permeability was measured on day 18, followed by passive sensitization and measurement of passive oral anaphylaxis on day 19 (Figure 3G).