Changes in cellular dry mass during macrophage development.

Measurements of dry mass were made on developing human macrophages in suspension culture using a scanning and integrating microinterferometer. The mean dry mass (+/- SEM) of day 0 monocytes of 19 healthy individuals was 53.6 +/- 2.4 pg. There was a significant increase in cellular dry mass over the period of culture, mean values at 2, 4 and 6 days being 61.1, 79.8 and 110.4 pg, respectively. A comparison of the results with those obtained previously by ultrastructural morphometry inferred that there is a disproportionate increase in the water content of macrophages during development. The technique may have potential for investigating changes in mononuclear phagocytes in clinical states.