The phagocytic capacity of macrophages in the S phase of the cell cycle

An inflammatory reaction was induced in the peritoneal cavity of mice. Two days later, the peritoneal macrophages, containing a proportion of S-phase (DNA-synthesizing) cells, were harvested and adhered to glass. Then the S-phase macrophages were labeled with ³H]thymidine (radioautography) and the macrophage monolayers were tested with regard to their ability to phagocytose immunoglobulincoated sheep red blood cells (SRBC). The percentages of S-phase macrophages which had phagocytosed SRBC were a little lower than those found for G-phase (G₁ + G₂) cells. Otherwise, the number of phagocytosed SRBC per macrophage was about equal for macrophages in both phases, and they both responded well by increasing the phagocytosis when the SRBC: macrophage ratio was increased. The S-phase macrophages also phagocytosed latex beads and zymosan particles efficiently.