Phagocytosis of nerve growth factor-coated erythrocytes in neuroblastoma rosette-forming cells

At 2 degrees, murine C1300 neuroblastoma cells bound NGF-coated sheep erythrocytes and formed rosettes. When the temperature was raised to 37 degrees, the neuroblastoma cells underwent a rapid transformation characterized by microtubule formation, which occurred under the membrane surface close to the points of contact with the attached red cells. Cytoplasmic processes filled wit- microtubules were then emitted by the cell body and surrounded the red cells. Within 20 to 30 min, the attached erythrocytes were phagocytized. Interiorization of membrane-bound erythrocytes-antibody-complement complexes by neuroblasto-a cells could be similarly induced at 37 degrees. In both cases, the extent of phagocytosis was decreased when microtubule formation was blocked with colchicine or vinblastine. Complete inhibition was obtained only by pretreatment of cells with cytochalasin B, a strong inhibitor of microfilament contraction. The role played by the microtubules and the microfilaments in promoting the phagocytosis of the attached erythrocytes is discussed.