Appearance of granulocyte-macrophage colony-stimulating factor activity at allergen-challenged cutaneous late-phase reaction sites.

The cytokines IL-3 and granulocyte-macrophage CSF (GM-CSF) activate and/or prime monocytes, basophils, and eosinophils for a number of proinflammatory events in vitro. It was hypothesized that IL-3 and GM-CSF might also participate in the local inflammatory cascades that occur at cutaneous blister sites after Ag challenge in vivo. The M-07e megakaryocytic leukemia cell line, which proliferates in response to IL-3 or GM-CSF, was used to determine whether these cytokines were present in fluids derived after Ag challenge in the cutaneous blister chamber model. Fluids from blister chambers after either Ag (timothy grass, orchard grass, or ragweed) or vehicle control challenge were collected hourly for 12 h from nine patients with allergic rhinitis. Cytokine (IL-3/GM-CSF) activity was modestly elevated at 4 h after Ag challenge compared to control with the median of maximal proliferation 4% (range, 2 to 22%) vs 2% (range, 1 to 14%), respectively (Ag vs control, p < 0.03). Activity peaked at 7 h (Ag = 10%, range 1 to 12%, vs control = 1%, range 1 to 9%, p < 0.02) and then steadily declined. No increase in cytokine activity over control was seen in Ag-challenged nonatopics (n = 5, p = NS), indicating that release did not result from a nonspecific effect of the Ag solution. Neutralization of cytokine bioactivity in pooled late phase reaction (LPR) fluids from h 4 to 12 (n = 5) with anti-IL-3, anti-GM-CSF, or both antisera revealed that the majority of the activity was GM-CSF. To better quantify cytokine levels, pooled LPR fluids prepared from an additional 11 subjects were concentration-dialyzed (10x) and tested for cytokine activity. Pooled fluids from Ag-challenged sites contained a median of 625 pg/ml (range, 30 to 1250 pg/ml) GM-CSF equivalents, whereas those from the vehicle control-challenged sites contained a median 30 pg/ml (range, 30 to 300 pg/ml) GM-CSF equivalents (p < 0.004 Ag vs control groups, n = 11). Concentrated fluid from Ag- and control-challenged sites in two nonatopic subjects contained < 10 pg/ml cytokine activity. To evaluate the IL-3 and GM-CSF activity with a separate technique, ELISA were performed on separately pooled blister fluids from six atopic subjects. Although no IL-3 activity was detected after Ag challenge in these six subjects, all of them demonstrated levels of GM-CSF at Ag-challenged sites comparable to that found in the bioassay.(ABSTRACT TRUNCATED AT 400 WORDS)