Protein content and enzymatic assays of interstitial fluid from some normal tissues and transplanted mouse tumors.

Abstract

SUMMARY Microscale assaysarereportedoninterstitial fluidsamplestakenfromsolidunicentrictumortransplants. Comparison wasmadeoftheproteincontentandenzymaticactivity ofnormalmouseplasmaandperitoneal fluidinthesamestrainofmice.Thecell-freetumorfluidhadahigherproteincontent,about5percent,thantheperitonealfluid.Thetotal“over-allâ€sdipeptidase activitypervolumewasincreasedabout40—100times;thearginaseandglutathion@reductaseactivitieswerelikewiseincreasedfrom5upto@0times,andthecatheptic activity atpH4.5showedonanaverageathreetofourfoldincreaseinactivityoverthecorrespondingnormalplasmaactivities.Theobservedincreasesinenzymaticactivitycannotbeduetoageneralproteinretentioninthetumorcompartment. Itissuggestedthatthelocalenzymaticincreaseintumorfluidsisbroughtaboutmainlybyleakageofproteinsfromthetumorcells;thisviewissupportedbyotherindependentinvitrodata.Someimplicationsarementionedwithreferencetotheutilization ofinterstitial proteinsforcellnutrition. Theincreasedcathepticactivityseemsfurthertohaveabearingontheextracellularproteolysis postulated topartake inthedestructive activityoftumorcells.Theobservationsprovideadditionalevidencethatneoplasticcellsarecharacterizedbyincreasedpermeabilityalsounderinvivoconditions.Information isscantastothechemicalcompositionoftheinterstitial fluid.Inthecaseofthenormaltissuefluid,currentpostulations (8,@6)arebasedmainlyondataobtainedfrominducededemafluids(i),intracavitary effusionsofvariouskinds,includingthoseduetothepresenceoftumors,andforemostondataobtainedfromlymph