Polymorphonuclear leukocyte chemiluminescence induced by Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus in serum and saliva

The ability of different strains of Actinobacillus actinomycetemcomitans (A.a .) and Haemophilus aphrophilus (H.a .) to trigger activation of an oxidative burst in human polymorphonuclear leukocytes (PMNL) was examined by measuring the luminol‐amplified light emission ‐ chemiluminescence (CL) ‐ from these cells. Bacterial cells were incubated with PMNL from one healthy subject, in the presence of either active serum, heat‐inactivated serum, saliva, or saliva and active serum. In the presence of active serum, all five H.a . strains and two out of five A.a . strains triggered a CL response. The CL induced in the presence of heat‐inactivated serum was considerably less than that achieved with fresh serum. In the presence of only saliva, all strains induced considerably weaker CL responses than those induced in the presence of saliva with active serum. In the presence of serum, intracellular reactions appeared to be the main source of CL, while addition of saliva and active serum increased the extracellular CL. The results indicate that strain‐dependent differences exist among A.a . strains in their ability to trigger the oxygen‐dependent bactericidal mechanisms of human PNML. In contrast, the CL patterns of H.a . strains were equivalent. Various factors in the environment, such as activated complement and salivary compounds, affect the interaction of these species with neutrophils.