Characterization of the effect of influenza virus on polymorphonuclear leukocyte membrane responses

Chemotactic behavior is a complex cellular response to chemical environmental stimuli. For polymorphonuclear leukocytes (PMNs), such behavior involves net migration as well as changes in cell shape and cell orientation. Accordingly, we have applied computer-interfaced video microscopy to analyze cell shape and orientation in control and patient PMNs migrating under agarose. From a digitized tracing of the PMNs at the leading front of migration, cells were characterized in terms of area, circumference, and longest dimension. A shape factor and angle of orientation were computed. Numerical shape factors discriminated three PMN morphologies: polar, apolar, and hyperpolar. Only polar cells could be oriented. Orientation of polar cells was defined as toward, away, or disoriented with respect to the chemotactic gradient. Apolar cells were considered to be nonoriented. Of PMNs from healthy controls, 30 +/- 5% of the cells were oriented toward and 11 +/- 4% of the cells were oriented away from the gradient. For PMNs from patients with localized juvenile periodontitis, a 40% deficit in net migration was associated with reduced orientation toward (5 +/- 2%) and elevated orientation away from the gradient (33 +/- 9%). PMNs from a panel of patients with thermal injury showed reduced migration and orientation toward the gradient associated with elevated percentages of apolar cells. Such analysis of PMN polarization and orientation of the leading front permitted calculation of a chemotactic behavior index. Application of this multiparameter index to the analysis of the chemotactic response may identify PMNs that are defective, but not by evaluation of any single variable.

Analysis of Polarization and Orientation of Human Polymorphonuclear Leukocytes by Computer-Interfaced Video Microscopy

MacFarlane¹,

Herzberg²,

Nelson

1987

Influenza A Virus Alters Structural and Biochemical Functions of the Neutrophil Cytoskeleton

Wheeler

Winkler

Seeds

et al. 1990

Influenza A virus (IAV) has previously been shown to alter chemotactic, oxidative, and secretory functions of polymorphonuclear leukocytes (PMNL). Because of the role of cytoskeletal proteins in these processes, studies were carried out to determine if IAV altered the PMNL cytoskeleton. PMNL were incubated with buffer of IAV, stimulated with f-met-leu-phe (FMLP), fixed and stained with NBD-phallacidin (NBD-Ph) and studied by flow cytometry. Mean F-actin fluorescence was increased 18% in virus treated cells pre-FMLP stimulation and 13% 5 and 10 min post-FMLP (P less than .03); no significant difference in F-actin fluorescence was noted in virus treated PMNL 15-30 s post-FMLP compared to control cells. PMNL exposed to the same conditions were solubilized and actin content was determined following SDS-PAGE of triton insoluble precipitates. Increased actin was recovered from virus treated compared to buffer treated cells before and after FMLP stimulation in the 8,000g precipitates (P less than .001). Immunofluorescent microscopy studies of F-actin distribution were done in PMNL stained with NBD-Ph following FMLP stimulation for 10 min. These studies showed an increased lamellipod F-actin/uropod F-actin ratio in PMNL pre-incubated with IAV compared to controls (4.6 vs. 1.0; P less than .025). Phosphorylation of specific cytoskeletal proteins was examined after immunoprecipitation. IAV alone altered phosphorylation of both vimentin and vinculin, and in stimulated PMNL virus led to decreased phosphorylation of vimentin and vinculin. These data show distributional and biochemical effects of IAV on PMNL cytoskeletal proteins, indicating additional targets for IAV interference in the PMNL signal-transduction-function process.

The Ability of Polymorphonuclear Leukocyte Priming Agents to Overcome Influenza A Virus-Induced Cell Dysfunction

Abramson

Wagner

Ralston

et al. 1991

The major mortality and morbidity resulting from influenza virus infections are due to secondary bacterial infections which occur in association with virus-induced inhibition of polymorphonuclear leukocyte (PMNL) function. The present study was undertaken to determine if compounds which prime PMNL function to subsequent stimulation with N-formylmethionyl-leucylphenylalanine (FMLP) or phorbol 12-myristate 13-acetate (PMA) can overcome influenza A virus (IAV)-induced inhibition of the PMNL chemiluminescence response to these stimuli. Granulocyte-macrophage colony stimulating factor (GM-CSF), guanosine triphosphate (GTP), and 1-oleoyl-2-acetylglycerol (OAG) were able to prime the PMNL response to FMLP and/or PMA and totally or partially overcome IAV-induced PMNL dysfunction in cells stimulated with FMLP or PMA. A direct correlation was found between the extent of PMNL priming due to GM-CSF, GTP, and OAG and the capacity of these compounds to overcome virus-induced PMNL dysfunction. The implications of these findings in regard to the mechanism by which priming agents overcome IAV-induced cell dysfunction and the potential of these compounds as therapeutic agents to treat secondary bacterial infections are discussed.