ABSTRACT

Kirtlandetal.(100)measuredcyclicAMPproducedinvitrobylymphocytesfromhealthy donorsafteraddingmethyldopaandbylymphocytesfrompatientswhowerereceiving methyldopa.SignificantlyhigherlymphocytecyclicAMPconcentrationsweregeneratedby bothsetsoflymphocytescomparedwithlymphocytesfromhealthydonorswithoutmethyldopa present.Tomeasuretheeffectofmethyldopaonsuppressorcells,Kirtlandetal.(100)usedan assayofsuppressoractivitydescribedbyLipskyetal.(101).Theassayisbasedonthefinding thatpreincubationoflymphocytesbeforemitogenstimulationincultureleadstolessIgGbeing generatedbyBcells.ThisispurportedtobeduetoenhancementofsuppressorT-cellactivity aftertheinvitropreincubationphase.Kirtlandetal.(100)confirmedtheresultsofLipskyet al.(101)thatlesslgGwasproducedfollowingpreincubationoflymphocytes.Theyshowed thatifmethyldopawasaddedduringthepreincubationphase,thentheinhibitionoflgG generationduringmitogen-stimulatedculturewasnegated.TheamountoflgGgeneratedin vitro,followingadditionofmethyldopatothepreincubationphase,wassignificantlygreater thanthelgGgeneratedwithoutapreincubationphase.Similardifferenceswereobservedwhen lymphocytesfrompatientsreceivingmethyldopawerecomparedwithlymphocytesfromhealthy donors.Theseresultswereinterpretedtoshowthatmethyldopainterferedwiththenormal functionofsuppressorTcellstomoderateIgGautoantibodyproductionbyBcells.Using similartechniquestothoseusedbyKirtlandetal.(100),wealsoconfirmedtheeffectof preincubationoninvitrogenerationbyBcellsreportedbyLipskyetal.(101).Wecouldnot confirmthefindingsofKirtlandetal.(100)thatmethyldopahadanyeffectonsuppressor

functions,asdefinedbytheinvitroproductionoflgGfollowingapreincubationphase (102,103).WeagreedwiththefindingsofKirtlandetal.(100)thatmethyldopadepressedthe proliferativeresponseofmononuclearcellstomitogenstimulation.