Natural killer cell function and lymphocyte subpopulation profiles in inflammatory bowel disease.

Peripheral blood natural killer (NK) cell activity and lymphocyte subpopulation profiles were studied in 23 patients with inflammatory bowel disease (IBD) and in 16 healthy control subjects. NK activity was assessed by a 4-hr 51Cr release assay using K-562 erythroleukemia cell line targets. Both monocyte depleted and nondepleted lymphocyte preparations were tested using 50:1 and 25:1 effector to target cell ratios. Lymphocyte subpopulation profiles were determined by incubation of cell suspensions with the monoclonal anti-lymphocyte antibodies (OK-M1, OK-T4, Leu-4 and Leu-2) labeling with goat anti-mouse FITC and sorting by flow cytometry on the fluorescence-activated cell sorter (FACS). NK activity in patients with IBD showed wide variation, but mean activity was not significantly different from normal controls. Analysis of patient subgroups by disease activity, disease type, duration or treatment also failed to reveal significant differences from controls. Parallel measurements of peripheral blood lymphocyte subpopulations using these phenotypic markers revealed no significant differences between patients with IBD and control subjects.