title: Effects of cyclosporin on C57BL/6 splenocytes before and after culture with high-dose recombinant interleukin-2: implications for immunosuppression with cyclosporin.
abstract: Lymphokine-activated killer cells appear to arise from precursor cells bearing natural killer (NK) cell antigens. Cyclosporin (CsA) is a well-known immunosuppressive agent that can down-regulate NK cell cytotoxicity. Studies were initiated to evaluate the effects of CsA on splenocytes before and after exposure to recombinant interleukin-2 (rIL-2). Normal C57BL/6 mice receiving CsA at a dose of 100 mg/kg demonstrated a decrease in NK cell lysis against the YAC-1 lymphoma target in a 4-h chromium-release assay. When splenocytes obtained from CsA-treated mice were cultured for 3 days in complete medium containing 1000 U rIL-2/ml, they demonstrated a return of NK cell lysis to normal (mean cytotoxicity = 65 LU versus 60 LU for control and CsA-exposed splenocytes respectively; P, NS, five consecutive experiments) but revealed a decrease in the lysis of a NK-resistant target: the MCA-102 sarcoma (mean cytotoxicity = 20 LU vs 12 LU for control and CsA-exposed splenocytes respectively; P less than 0.02, five consecutive experiments). Fresh splenocytes cultured in media containing rIL-2 and CsA demonstrated a decrease in proliferation, cell-cycle S-phase fraction and cell yields compared to splenocytes cultured in media containing rIL-2 alone. In addition, a decrease in tumor cell lysis for NK-cell sensitive (mean percentage lysis = 98% vs 60%, rIL-2 vs rIL-2 + CsA; effector-to-target ratio 100: 1) and resistant targets (mean percentage lysis = 68% vs 28%, rIL-2 vs rIL-2 + CsA; effector-to-target ratio 100: 1) was also seen. CsA had no effects on the phenotypic antigenic expression of splenocytes cultured with high-dose rIL-2 although activated T cell antigens were down-regulated when fresh splenocytes were evaluated after in vivo exposure to CsA. These studies support the down-regulating effects of CsA on NK cell lysis and suggest that the rIL-2-activated cell population is heterogeneous as demonstrated by the differential down-regulation and recovery of NK-resistant cell lysis versus NK-sensitive cell lysis.
authors.affiliation: University of Calgary, Health Sciences Center, Canada.
authors.forename: F
authors.initials: F
authors.lastname: Sutherland
authors.forename: K
authors.initials: K
authors.lastname: Borkenhagen
authors.forename: L
authors.initials: L
authors.lastname: Temple
authors.forename: L D
authors.initials: LD
authors.lastname: Bryant
authors.forename: R
authors.initials: R
authors.lastname: Lafreniere
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003524:Cyclosporins / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D007274:Injections, Intraperitoneal; D007376:Interleukin-2 / Q000008:administration & dosage*; D007399:Interphase / Q000187:drug effects; D007694:Killer Cells, Natural / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008815:Mice, Inbred Strains; D010641:Phenotype; D011994:Recombinant Proteins / Q000008:administration & dosage*; D013154:Spleen / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D003524:Cyclosporins; D007376:Interleukin-2; D011994:Recombinant Proteins