Abstract: A compound of the formulaR.sup.1 --A.sup.2 --A.sup.1 --Asp-p-nitroanilide Iwherein:A.sup.1 is a residue of any of the naturally occurring .alpha.-amino acids or a homolog, analog or derivative of a natural .alpha.-amino acid;A.sup.2 is a residue of a lipophilic .alpha.-amino acid;R.sup.1 is alkylcarbonyl, phenalkylcarbonyl, alkoxycarbonyl, phenalkoxycarbonyl, alkylaminocarbonyl, phenalkylaminocarbcnyl or R.sup.2 --A.sup.3 whereinA.sup.3 is a residue of a lipophilic .alpha.-amino acid; andR.sup.2 is alkylcarbonyl, alkoxycarbonyl or phenylalkoxycarbonyl, anda method of detecting inhibitors of interleukin 1.beta. converting enzyme (ICE) comprising evaluating a test compound's capacity to inhibit the ICE-induced hydrolysis of a compound of the formula I. The greater the ability of a test compound to inhibit such hydrolysis, the greater its expected activity in treating inflammation as well as diseases whose pathogenesis is induced or sustained by interleukin-1.beta..