Protein kinase C (PKC) inhibitors inhibit primary (1-0) but not secondary (1-1) or cloned cytotoxic T lymphocytes.
The isoquinolinesulfonamide PKC inhibitors H-7 and H-8 inhibit primary, in vivo generated cytotoxic T lymphocyte (CTL) activity by 50% at concentrations approximating their reported Ki values for PKC, 6 uM and 15 uM respectively. However, a greater than ten-fold higher concentration of H-7 (100 uM) is required to reduce secondary or clone 8F CTL-mediated cytotoxicity by 50%. At this concentration H-7 is also reported to inhibit calmodulin (CaM)-dependent enzymes. To distinguish between the effect of 100 uM H-7 on PKC versus CaM the napthalenesulfonamide CaM antagonist W-7 was investigated. W-7 inhibited primary, secondary and clone 8F CTL-mediated cytolysis by 50% near its reported Ki value for CaM-dependent kinase activity, 12 uM. We conclude that W-7 and 100 uM H-7 reduce cytolysis by inhibiting CaM-dependent reactions and not PKC. Thus, these findings indicate that primary killers require both PKC- and CaM-dependent activation pathways for lethal hit delivery, whereas highly lytic cultured CTL use only one pathway dependent upon CaM.
Howcroft
T K
TK
University of Connecticut Medical School, Farmington 06032.
Tatum
S M
SM
Cosgrove
J M
JM
Lindquist
R R
RR
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000818:Animals; D002999:Clone Cells; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D007546:Isoquinolines / Q000494:pharmacology*; D051379:Mice; D010879:Piperazines / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D013449:Sulfonamides; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects* / Q000276:immunology
D007546:Isoquinolines; D010879:Piperazines; D013449:Sulfonamides; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C053177:N-(2-(methylamino)ethyl)-5-isoquinolinesulfonamide; C043204:N-(2-guanidinoethyl)-5-isoquinolinesulfonamide; D011493:Protein Kinase C