Quantitation of chemotactic factor generation in human sera

The indirect leucocyte migration inhibition assay--an endotoxin-sensitive chemokinetic assay. Part II

Depletion of agarose for endotoxins resulted in a low spontaneous migration of polymorphnuclear cells (PMNC). Re-addition of endotoxin, in casu lipopolysaccharide from E. coli 026:B6 (LPS), enhanced the spontaneous PMNC migration in a two-phased dose-response pattern, reaching maximum migration with LPS 1 x 10(-7) g/ml. Thus, the migration of PMNC under agarose seems to be a chemokinesis. Leucocyte migration inhibition factor (LIF), induced by PPD 50 micrograms/ml at endotoxin-free conditions, significantly reduced the PMNC migration compared to supernatants from control cultures, however not compared to the conventional limit of significance, MI = 0.80. With increasing PMNC migration there was an insignificant decrease in the MI. Addition of LPS, 1 x 10(-9) g/ml, during LIF induction caused a significant increase in LIF production, an effect which overshadowed the effect of PPD. Thus, the application of the conventional limit of significance, MI = 0.80, may result in false-negative or false-positive conclusions, depending upon the endotoxin contamination. A standardization of the endotoxin content in both steps of the indirect leucocyte migration inhibition assay seems mandatory in order to obtain a reliable and reproducible bioassay.

Acquired chemotactic inhibitors during infection with guinea pig cytomegalovirus

Factors involved in neutrophil and monocyte migrations were serially studied in strain 2 guinea pigs undergoing initial cytomegalovirus infection and sham-inoculated controls. All studies remained unchanged in uninfected animals. Monocyte migrations and neutrophil spontaneous migration remained unchanged in infected animals. However, transient abnormalities occurred early in infection, comprising a decrease in neutrophil-directed migration towards C5-derived chemotactic fractions (C5-fr) and a decrease in the chemotactic activity of zymosan-activated plasma. Consequently, the presence of neutrophil- and chemotaxin-directed inhibitors in plasma was investigated. Normal neutrophils, C5-fr, Escherichia coli-derived bacterial factor, and the synthetic peptide F-met-leu-phe were first incubated with control or infected plasmas and then assayed for directed migration and lysosomal enzyme release. Results indicated the de novo appearance of both neutrophil- and chemotaxin-directed inhibitory activities in plasma during early infection. The neutrophil-directed inhibition was heat stable (56 degrees C for 120 min) and nonspecific (responses to all chemotaxins were inhibited). The chemotaxin-directed inhibition was heat stable and C5-fr specific. The cytomegalovirus-induced inhibitors may be important in the enhanced susceptibility to concurrent opportunistic infections.

Neutrophil chemotaxis under agarose: a statistical analysis and comparison of the chemotactic response of cells from different donors

Distance of migration and cumulative cell count were determined in parallel to quantitate migration of polymorphonuclear leukocytes (PMNs) of healthy volunteers in the chemotaxis-under-agarose assay. The cumulative percent distributions of the rates of spontaneous migration in the absence of an attractant, of chemokinetic migration in zymosan-activated human serum (ZAS) incorporated in agarose, and of chemotactic migration toward ZAS were approximately normal. Cord blood PMNs are known to respond poorly to ZAS in vitro; this was used to determine whether the chemotactic indices (CI: ratio of migration toward ZAS to spontaneous migration) and the chemotactic differentials (CD: difference between migration toward ZAS and spontaneous migration) correlated with impaired chemotaxis under agarose. Both CI and CD values of cord PMNs were significantly low, indicating a positive correlation. The CI values of healthy volunteers correlated negatively with spontaneous migration, whereas the correlation of the CD values was neither negative nor positive. Since spontaneous migration of PMNS varies, the results support the use of CD values when comparing chemotactic responses of PMNs from different donors; e.g., the CD values were determined to evaluate the responsiveness of HLA-B27-positive PMNs, which we recently found to migrate under agarose toward ZAS more than HLA-B27-negative PMNs. The CD values of HLA-B27-positive PMNs were significantly high, indicating that the cells were high responders.

Chemotaxis under agarose utilizing human serum depleted of C-5 derived peptides

An immunoabsorbent column was made with antibody to trypsinized human C5. This column removed the chemotactic activity from zymosan-activated serum as well as from C5a des-arg-enriched fractions. Anti-trypsinized C5-absorbed human serum was substituted for unabsorbed human serum in the chemotaxis under agarose system. This resulted in significantly reduced random neutrophil migration with a negligible effect on C5a des-arg or FMLP-directed migration. The results indicate that much of the random migration observed in the chemotaxis under agarose system is due to C5-derived peptides present in normal human serum.