FRACTIONATION OF FELINE BONE-MARROW WITH THE SOYBEAN AGGLUTININ LECTIN YIELDS POPULATIONS ENRICHED FOR ERYTHROID AND MYELOID ELEMENTS - TRANSPLANTATION OF SOYBEAN AGGLUTININ-NEGATIVE CELLS INTO LETHALLY IRRADIATED RECIPIENTS

Feline bone marrow cells treated with the soybean agglutinin (SEA) lec tin are separated into two populations, the agglutinated SBA(+) fracti on containing predominantly cells of myeloid origin and the nonaggluti nated SBA(-) fraction consisting of cells primarily of the erythroid l ineage. FACScan analyses revealed a clear distinction of the cells bas ed on their light scattering properties, i.e., large cells and cells w ith high granularity were found in the SBA(+) fraction, whereas cells having a low forward light scatter and side light scatter were found i n the SBA(-) fraction. Colony-forming assays showed colony-forming uni t-granulocyte/monocyte (CFU-GM) cells to have a strong affinity for SE A because these were found almost entirely in the SBA(+) fraction; in contrast, burst-forming unit-erythroid (BFU-E)-forming cells were conc entrated in the SEA(-) fraction, When the marrow was fractionated by c ounterflow centrifugal elutriation (CCE), a differential binding to SE A among the CFU-GM forming cells was found, The SBA(-) fractions of ce lls collected at 21 and 25 ml/min contained primarily BFU-E forming ce lls, similar to that observed with whole marrow; the later CCE fractio ns, those collected at 32 ml/min and the rotor off fraction, when trea ted with SEA showed a small but significant number of CFU-GM cells in the SBA(-) fraction. T lymphocytes were found predominantly in the SBA (+) fractions of whole bone marrow and the CCE fractions. Successful a utologous marrow transplants were performed with the early CCE SEA(-) fractions. The latter cells were used for our initial transplant attem pts because ongoing studies in our laboratory had shown these cells to be free of any viral-containing cells when the marrow had been obtain ed from animals infected with the feline immunodeficiency virus. In su mmary, although SEA treatment of feline marrow yields a marked separat ion of CFU-GM and BFU-E progenitors, select CCE SBA(-) fractions conta in stem cells capable of providing hematopoietic reconstitution of let hally irradiated animals.