Kveim induced lymphocyte reactivity in patients and household contacts of patients with Crohn's disease.

In vitro lymphocyte thymidine uptake in response to validated Kveim antigen CR-1 was studied in 18 patients with Crohn's disease and in 30 of their household contacts. Two of the patients and 3 of the contacts demonstrated a stimulation index of 2 or greater. None of 15 control subjects demonstrated such reactivity. Lymphocytes from patient and household contact groups exhibited a greater mean increment in cpm than those from the control group (110, 130 and 33 cpm, respectively) (p < 0.05 and p < 0.005, respectively). This finding indicates a low level of lymphocyte reactivity to Kveim antigen in patients and in contacts, suggesting sensitization to Kveim antigen or to a cross-reacting antigen.