Table 4

Impaired apoptotic capacity of endogenous ceramide and ceramide-dependent receptor systems in TAM-67 transfectants

Treatment	U937/WT		U937/TAM
	ng/10⁶cells	rad equivalents	ng/10⁶ cells	rad equivalents
Control	269 ± 21	115 ± 5	287 ± 18	105 ± 5
SMase	2112 ± 925^4-a	5130 ± 261^4-a	273 ± 70^4-b	144 ± 36^4-b
rhTNF-α	1736 ± 265^4-a	3662 ± 142^4-a	326 ± 92^4-c	127 ± 22^4-c
Fas monoclonal antibody	2469 ± 416^4-a	4812 ± 315^4-a	302 ± 104^4-d	138 ± 47^4-d

In parallel trials, U937/WT cells and U937/TAM cells were treated with bacterial SMase (50 munits/ml) or exposed to rhTNF-α (100 nm) or monclonal antibody directed against Fas (1.5 μg/ml) for 9 hr; apoptotic DNA damage was then measured by quantitative spectrofluorophotometry as described in Materials and Methods.

↵4-a Increased vs. untreated controls (p < 0.01).
↵4-b Decreased vs. SMase in U937/WT (p < 0.01).
↵4-c Decreased vs. rhTNF-α in U937/WT (p < 0.01).
↵4-d Decreased vs. Fas antibody in U937/WT (p < .01).