Activation of the 5-lipoxygenase pathway in E-mast cells by peanut agglutinin

Mouse E-mast cells were differentiated and grown by culturing bone marrow cells in medium containing WEHI-3-conditioned medium. These cells possess surface receptors to the following agglutinins: peanut (PNA), concanavalin A (Con A), and soybean (Sb). One to 200 micrograms of PNA/10(6) E-mast cells selectively stimulated the generation of leukotriene C4 (LTC4) in the absence of beta-hexosaminidase release. Exposure of 10(6) E-mast cells to 1 to 200 micrograms Con A or Sb had no effect either on preformed mediator release or on the generation of leukotrienes. LTC4 was quantitated by integrated UV absorbance after resolution by reverse phase high pressure liquid chromatography. The optimum release of LTC4 (13.2 ng/10(6) cells) was achieved by 50 micrograms of PNA/10(6) cells. The response is characterized by the inhibition by excess amounts of PNA. The amount of LTC4 generated during optimal PNA stimulation is lower than the amount produced after stimulation by IgE-antigen or by calcium ionophore A23187 (19.8 ng and 148 ng, respectively). The release of LTC4 began within 5 min after PNA stimulation, and reached a plateau within 45 to 60 min at 37 degrees C. This kinetic pattern is similar to that observed after calcium ionophore A23187 stimulation of these cells. The results suggest that PNA is capable of selectively activating the 5-lipoxygenation of arachidonic acid without affecting beta-hexosaminidase secretion. Apparently, separate biochemical events may serve to mobilize each class of mediators.