Recombinanthumanprolactin(rhPRL)wasadministeredtohuPBL-SCIDmicetodetermineitseffectsonhumanimmunologicreconsfitutionandfunction.ThehuPBL-SCIDmiceweregiven10μgI.p.InjectionofrhPRLeveryotherdayforatotalof10injectionsafterhuPBLweretransferred.TheresultsdemonstratedthatrhPRLimprovedtheengraftmentoflymphocytesintothymus,lymphnodesandspleens,showingthatthecellularitiesoftheseorgansincreasedalthoughthecellularitiestendedtovarydependingonthedonor.TheamountsofhumanTcells(HLA-ABC+/CD3+)increasedgreatlyinthymus(14.2folds),spleen(4.16folds)andlymphnodes(40.18folds)afterrhPRLinjections.TheamountsofhumanBcells(HLA-ABC+/CD19+)alsoincreasedgreatlyinlymphnodes(42.5folds)andspleen(5.78folds).ThelymphnodecellsfromtherhPRL-treatedhuPBL-SCIDmiceweremoresensitivetoPHAstimulation([3H]thymidineincorporation).ThesupernatantofPHA-stimulatedPBLfromrhPRL-treatedhuPBL/SCIDchimerismcontainedmorecytokines(IFN-γandIL-2).Thenaturalcytotoxicityagainsthumansensitivetargetcells,K562cells,fromspleenandbonemarrowofhPBL/SCIDchimerismwassignificantlyenhancedbyrhPRLadministration.ThelymphnodecellswerestimulatedwithLPSinvitrofor3daysandthelymphocytesfromtherhPRL-treatedhuPBL-SCIDmiceweremoresensitivetomitogenstimulation.BothserumtotalIgGlevelandIgMlevelofrhPRL-treatedhuPBL/SCIDchimerismwereincreased,andevenwithoutDT-rechallengethebaselineofDT-specificIgGwaselevatedafterrhPRLtreatmentinhuPBL-SCIDmice.Thus,rhPRLstimulationpromotesreconstitutionofhumanimmunesysteminhuPBL-SCIDmice.