Recombinant human interleukin-2-induced mitogenic proliferation of in vitro unstimulated bovine intestinal lymphocytes.

Recombinant human interleukin-2 (rHIL-2) in the absence or presence of additional stimuli, was able to induce and support the proliferation of lymphocytes isolated from the intra-epithelium, lamina propria and Peyer's patches of the small intestine of normal adult cows. Although dose-dependent effects of rHIL-2 were observed with all three cell populations, concentrations as low as 2.5 U/mL were able to induce DNA synthesis as measured by tritiated thymidine incorporation. Furthermore, rHIL-2 as low as 5.0 U/mL was shown to significantly enhance lymphocyte proliferation in response to mitogenic stimulation. These proliferative responses to rHIL-2 were detected within two days of culture and peaked after five days. Although the extent of the blastogenic response was variable in individual animals, the general pattern of time-course and dose-response to rHIL-2 was similar in all animals tested. The response of all three leukocyte populations to rHIL-2 was dependent on the presence of adherent accessory cells and/or 2-mercaptoethanol. Both nylon wool nonadherent (T cells, null cells) and adherent cells (B cells) were shown to be responsive to rHIL-2. These studies demonstrate that bovine lymphocytes isolated from different anatomical locations of the small intestine are capable of proliferation in response to xenogenic IL-2 without in vitro preactivation signals.(ABSTRACT TRUNCATED AT 250 WORDS)