The accumulation of bactericidal lipids in staphylococcal abscesses

Abscesses were generated in the peritoneal cavity of mice by the inoculation of 10(9) staphylococci. Abscess weight increased rapidly, reaching about 200 mg by the fourth day; for the next 60 days, abscess weight increased only slightly. The amount of total lipid increased during abscess development, attaining a peak level of about 19 mg per abscess at 7 days before decreasing. Almost all of this lipid resulted from the accumulation of neutral lipids. The small increases seen in the phospholipid and glycolipid fractions could be accounted for through the accumulation of host cellular elements in the abscess. Leucocytes containing cytoplasmic lipid droplets were first seen 4-12 h after infection and these cells were widely scattered around the periphery. During the next 2 days, the number of cells with lipid droplets increased markedly and lipid droplets were also found in the deeper portions of the abscesses. Although lipid droplets were found subsequently throughout the abscess, the greatest amounts always occurred in the leucocyte zone immediately proximal to the connective tissue capsule. During abscess development, the bactericidal activity also increased rapidly, reaching a maximum by the seventh day and declining thereafter.