Phagocytosis of latex particles in relation to the cell cycle in 3T3 cells

Cultures of 3T3 cells, synchronised by serum deprivation, were shown to phagocytose latex beads of 0.81 micrometer diameter more avidly in the G1 phase of the cell cycle. The maximum rate of about 0.12 particles/cell/hour was recorded 12 h after stimulation with 10% fetal bovine serum. After 24 h, when mitosis was beginning, the uptake fell to just above the unstimulated level of 0.06 particles/cell/hour. Exocytosis was linear and only 7% of the total cell-associated latex was released in 30 h. Internalisation of latex beads was demonstrated by electron microscopy. No uptake was detected in experiments conducted at 4 degrees C.