RESUMEN
OBJECTIVE AND DESIGN: To compare the production of hyperalgesic substances by cells from aged (A; 24-month) and juvenile (J; 2-month) rats. MATERIAL AND METHODS: 4 x 10(5) purified mononuclear cells from J and A were 2 h-stimulated (test) or not (control) by 250 microg lambda-carrageenan/well. Supernatants (0.1 ml) were intraplantarly (ipl) injected in rat paws and development of mechanical hyperalgesia, in grams, evaluated. Rat interleukin 2 (IL 2) and prostaglandin E2 (PGE2) were also assessed for hyperalgesia development. RESULTS: Test supernatants from A compared with J induced significantly less hyperalgesia (-56 +/- 8.1 and -88.4 +/- 4.6 g, respectively, p < 0.05, ANOVA t test). Local injection of a specific, but not a control, antiserum against IL 2 significantly blocked both pure IL 2- and stimulated supernatants-derived hyperalgesia. In contrast to PGE-like materials, IL 2 content in supernatants was compatible with hyperalgesia development. CONCLUSIONS: Hyperalgesia induced by test supernatants was significantly less intense when derived from aged animals. IL 2 may have accounted for such hyperalgesia.