Elimination of Malignant Clonogenic Cells from Human Bone Marrow Using Multiple Monoclonal Antibodies and Complement1

A clonogenicassayhasbeendevelopedthat utilizesBurkitt's lymphomatumor cell linesto detect eliminationof up to 5 logs of tumorcellcontaminationwithinhumanbonemarrow.Different Burkitt's lymphomalinesbearoneor moreof agroupof markers, includingcommonacute lymphoblasticleukemiaantigengp26 (glycoproteinwith a molecularweight of 26,000),B1, surface membraneimmunoglobulin, HLA,fo-microglobulin, andla.Burk itt's tumorcellsof the Namalwalinehavebeenmixedwitha 20fold excessof irradiatedhumanbonemarrowcells.After treat mentwith one or moremonoclonalantibodiesand rabbitcom plement(RC),mixtures have been grown on a monolayerof irradiatedhumanbonemarrowcellsandtumorcellsenumerated by limitingdilution. Multipletreatmentswith antibodyand RC were moreeffectivethan a singletreatmentin destroyingclon ogenic tumor cells which bore relevantdeterminants.Human serumcomponentsinhibitedthe lyticactivityof RCin the pres enceof murinemonoclonalantibodies.The total concentration of bonemarrowcellsprovedcriticalin determiningthe complete eliminationof tumor. Incubationof the Namalwatumorcell line with RC and the J2 anti-gp26eliminatedmore than 3 logs of malignantcells from a 20-foldexcessof humanbonemarrow. Combinationsof two monoclonal antibodiesweremoreeffective thananysingleantibodyin eliminatingNamalwacells.A combi nationof threemonoclonal reagentswasno moreeffectivethan a combinationof J2 andB1 or J2 andJ5 ineliminatingNamalwa cells.Treatmentof humanbone marrowwith three antibodies and RCdid not, however,producea selectivelossof nonmalignantGM-CFU-C, CFU-E,or BFU-E.