Response of bovine intestinal leukocytes to recombinant bovine interleukin-2

The effects of recombinant bovine interleukin-2 (rBoIL-2) on unstimulated leukocytes isolated from the small intestine of normal adult cows were examined in vitro. While intraepithelial leukocytes (IEL) were shown to be poorly responsive, leukocytes isolated from the lamina propria (LPL) and Peyer's patches (PPL) of the same animals responded to rBoIL-2 in the absence of exogenous stimuli. Although the effect of rBoIL-2 on all three cell populations was dose-dependent, stimulation was observed at low doses (less than or equal to 10 mu/ml) of rBoIL-2 only when 2-mercaptoethanol (2-ME) or additional mitogenic signals (ie. ConA) were provided. However, higher doses of rBoIL-2 stimulated the proliferation of IEL (greater than or equal to 100 mu/ml), LPL and PPL (greater than or equal to 20 mu/ml) even in the absence of 2-ME or exogenous lectins. The proliferative effects of rBoIL-2 were detected within 2 days of culture and peaked after 5 days. Adherent cell (AC) depletion of PPL resulted in a marked reduction of IL-2-induced proliferation which could be restored by adding back AC (7%) or supplementing the cultures with 2-ME (50 microM). Furthermore, addition of 2-ME not only substituted for AC, but highly augmented the proliferative response to rBoIL-2. Nylon wool fractionation of PPL revealed that both T-cell-enriched (nylon wool non-adherent) and T-cell-depleted (nylon wool-adherent) populations were responsive to rBoIL-2 in the presence of AC and/or 2-ME.(ABSTRACT TRUNCATED AT 250 WORDS)