ANTI-CD3 ACTIVATION OF HUMAN CD4(-CELLS INCREASES EXPRESSION OF THE INTRACELLULAR BETA-ENDORPHIN ENDOPEPTIDASE (IDE() T)GAMMA-EPGE)/

In this study, increased expression of an endopeptidase hydrolyzing be ta-endorphin (beta-Ep) to gamma-endorphin (gamma-Ep, beta-Ep1-17) was observed upon immobilized anti-CD3 stimulated activation of human peri pheral blood CD4(+) T cells (hCD4(+) T cells). Although freshly isolat ed hCD4(+) T cells are devoid of significant beta-Ep endopeptidase act ivity (< 0.1 nmol h(-1) 10(6) cells(-1)), activation of these cells wi th immobilized anti-CD3 results in a time dependent appearance of beta -Ep endopeptidase activity which reaches a maximal value of 17.4+/-0.4 8 nmol h(-1) 10(6) cells(-1) after 48 h of culture. Significant up-reg ulation of both mRNA encoding IDE/gamma-EpGE and immunoreactive protei n are observed in anti-CD3 stimulated hCD4(+) T cells, indicating tran scription and translation of IDE/gamma-EpGE may be elevated. No signif icant hydrolysis of exogenous beta-Ep is observed with intact hCD4(+) T cells whether quiescent or activated or from preparations of hCD4(+) T cell membranes. Therefore, this activity appears to be intracellula r. Immunoreactive IDE/gamma-EpGE is detected inside activated hCD4(+) T cells. Analysis of metabolites generated upon hydrolysis of beta-Ep with lysed activated hCD4(+) T cell preparations identified the presen ce of: beta-Ep1-18, beta-Ep2-18, beta-Ep1-17, beta-Ep2-17, beta-Ep18-3 1, beta-Ep19-31, beta-Ep1-13, beta-Ep2-13, beta-Ep18-26, and beta-Ep20 -31 as major metabolites and the majority of these are consistent with beta-Ep hydrolytic activity attributable to IDE/gamma-EpGE. (C) 1998 Elsevier Science B.V. All rights reserved.