Table 2. Effects of Herbimycin A on... | American Society of Hematology

Table 2.

Effects of Herbimycin A on IFN-γ–Induced PLA₂ Activity and AA Release by HL-60 Cells

Treatment	PLA₂ Activity (% control)		AA Release (% control)
	Membrane	Cytosol
None	100 ± 14	100 ± 8	100 ± 12
IFN-γ	248 ± 24^*	241 ± 23^*	652 ± 43^*
12 hours
Herbimycin A	102 ± 12	106 ± 13	104 ± 12
Herbimycin A + IFN–γ	98 ± 13	106 ± 12	637 ± 36^*
16 hours
Herbimycin A	103 ± 14	107 ± 15	99 ± 11
Herbimycin A + IFN–γ	104 ± 12	111 ± 13	611 ± 65^*
20 hours
Herbimycin A	109 ± 12	112 ± 15	103 ± 8
Herbimycin A + IFN–γ	102 ± 7	104 ± 13	656 ± 47^*

Treatment	PLA₂ Activity (% control)		AA Release (% control)
	Membrane	Cytosol
None	100 ± 14	100 ± 8	100 ± 12
IFN-γ	248 ± 24^*	241 ± 23^*	652 ± 43^*
12 hours
Herbimycin A	102 ± 12	106 ± 13	104 ± 12
Herbimycin A + IFN–γ	98 ± 13	106 ± 12	637 ± 36^*
16 hours
Herbimycin A	103 ± 14	107 ± 15	99 ± 11
Herbimycin A + IFN–γ	104 ± 12	111 ± 13	611 ± 65^*
20 hours
Herbimycin A	109 ± 12	112 ± 15	103 ± 8
Herbimycin A + IFN–γ	102 ± 7	104 ± 13	656 ± 47^*

Cells were treated for 12, 16, and 20 hours with herbimycin A (1 μg/mL). When PLA₂ activity was to be measured, cells were stimulated with 2,000 U/mL of IFN-γ during the last 4 hours of the incubation period with herbimycin A. PLA₂ activity in particulate and soluble fractions was determined by hydrolysis of [arachidonyl-¹⁴C]PtdCho in the presence of 5 mmol/L DTT and 150 nmol/L Ca²⁺. When AA release was to be measured, cells were labeled with 5 μCi/mL of [³H]arachidonic acid for 60 minutes and stimulated with IFN-γ (2,000 U/mL) for 2 minutes at the end of incubation period with herbimycin A. After treatment, cells were pelleted and the resulting supernatant was counted to determine levels of released label. The data (means ± SD) are expressed as percentage of the control level obtained from three independent experiments assayed in duplicate.

Significantly different (P < .05, Student's t-test) from controls.

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