MethotrexatePolyglutamic AcidAntirheumatic AgentsFolic Acid AntagonistsTetrahydrofolate DehydrogenaseArthritis, RheumatoidAminopterinAntimetabolites, AntineoplasticLeukemia L1210Reduced Folate Carrier ProteinTrimetrexateFolic Acidgamma-Glutamyl HydrolaseDrug Therapy, CombinationLeucovorinTetrahydrofolatesAbortifacient Agents, NonsteroidalCyclophosphamideDrug ResistanceTreatment OutcomeAntineoplastic Combined Chemotherapy ProtocolsImmunosuppressive AgentsSulfasalazineVincristineDeoxyuridinePrecursor Cell Lymphoblastic Leukemia-LymphomaDrug Administration Schedule6-MercaptopurineDermatologic AgentsPregnancy, EctopicFluorouracilFormyltetrahydrofolatesFolate Receptors, GPI-AnchoredDoxorubicinPhosphoribosylaminoimidazolecarboxamide FormyltransferaseOsteosarcomaInjections, SpinalPrednisoneDose-Response Relationship, DrugCytarabineThymidylate SynthaseLeukemia, LymphoidHydroxychloroquineCentral Nervous System NeoplasmsPregnancy, TubalSarcoma 180Pteroylpolyglutamic AcidsIsoxazolesPsoriasisAsparaginaseGestational Trophoblastic DiseaseRemission InductionBiological TransportHydroxymethyl and Formyl TransferasesProbenecidMucositisNucleotide DeaminasesCarcinoma, Ehrlich TumorDouble-Blind MethodVinblastineAntibodies, MonoclonalArthritis, JuvenileCombined Modality TherapyArthritis, PsoriaticTrophoblastic NeoplasmsTime FactorsAdministration, OralLeukemia L5178CisplatinHypoxanthines