Influence of blood cells on the expression of bacteriocin-like activity in Neisseria meningitidis

The inhibitors responsible for the bactericidal activity found in four strains of Neisseria meningitidis were strongly bound to or inactivated by blood cells. The bactericidal effects were specifically influenced by human cells of types O, A, B and AB. Cells from horse, sheep and rabbit had no significant effect. The bacteriostatic effect observed in one strain of N. meningitidis was more moderately reduced in the presence of animal cells as well as human cells. The effects of the blood cells were connected with pellets from lysates of the blood cells. The bacteriostatic effect was also moderately reduced in the presence of plasma, hemoglobin and methemoglobin regardless of origin, and to some extent of cytochrome C. CaCl2 slightly enhanced the bacteriostatic effect.