If it feels so good, it couldn't be bad, right? Not quite, rave child. Research has shown that Ecstasy (MDMA, or just "E"), the popular recreational drug that blisses you out and keeps you dancing 'til noon, can cause chronic depression in later life. Now it seems that E may undermine the immune system, too. In a recent study of 17 healthy guys, European researchers found that a single 100 mg dose of E caused a 30 percent drop in CD4 cells, while two hits four hours apart caused a 40 percent drop. Levels rebounded within a day or so, but not always to baseline. Quality was also queered. It's no surprise that E reduced CD4s' infection-fighting punch -- the drug not only contains immune-unfriendly amphetamines but increases production of cortisol, a cell-suppressing hormone. What this implies for HIVers who like to "roll" is a no-brainer: Fewer CD4 cells equal more HIV...not to mention that E can pump up protease inhibitors and NNRTIs to deadly levels in the blood. If you can't ki-ki without E, dancing queen, maybe it's time to find a better DJ.