Complement Proteins and Macrophages

Abstract

Cobra venom factor was used for the detection of factor B synthesized by mouse peritoneal macrophages. This method was shown to be specific for factor B assay by neutralization by antimouse factor B antibody. The amount of factor B in the culture supernatant, assessed by this method, was found to be dependent on the medium used for cultivation of macrophages. The addition of 25% L cell‐conditioned medium to minimal essential medium (LCM‐MEM) enhanced the production of factor B and also of lysozyme. Kinetic analysis in LCM‐MEM showed that factor B produced by 6 × 104 cells/cm2 increased up to 72 hr and reached a plateau at 96 hr. The amounts of factor B and lysozyme produced in LCM‐MEM depended upon the number of macrophages. Production of factor B was completely inhibited by 1 μg of cycloheximide per ml and was restored by its removal.

Complement Proteins and Macrophages

“…This discrepanc y may be explained on the basis of either the medium used for the cultivation of the macrophages or the route of administration of the stimulant. We reported previously that the L cell-conditioned medium used in the present experiments strongly enhanced the rate of factor B production (14).…”

“…Eagle's minimum essential medium (MEM) and MEM containing 5% heated fetal calf serum and 25% L cell-conditioned medium (LCM-MEM) were used throughout the experiments as reported previously (14).…”

“…At the same time, the production of lysosomal and cytoplasmic enzymes which are synthesized by normal macrophages is greatly enhanced (2,13,30). The first (C1), second (C2), third (C3), fourth (C4), and fifth (C5) components, factor B, factor D, properdin and some regulatory components of complement are known to be normally synthesized and released, like lysosomal enzymes, by peripheral blood monocytes and peritoneal resident macrophages (5,6,10,14,20,22,32). Although variation in serum complement components in humans and rats after bacterial infection, and in mice after the in vivo administration of turpentine oil, has been described (9,21), the responsiveness of complement-producing cells to a variety of stimuli has not been fully analyzed as to their capacity to produce and/or secrete the complement components.…”