The fibrinolytic pathway of human plasma. II. The generation of chemotactic activity by activation of plasminogen proactivator

The conversion of plasminogen proactivator to plasminogen activator by Hageman factor fragments results in the generation of chemotactic activity for human neutrophils. This chemotactic activity can be distinguished from that generated by Hageman factor activation of prekallikrein and is demonstrable in plasma that is genetically deficient in prekallikrein (Fletcher factor deficiency). Both the plasminogen-activating activity and chemotactic activity produced by the interaction of Hageman factor fragments and plasminogen proactivator to yield plasminogen activator were inhibited by diisopropyl fluorophosphate (DFP) indicating an essential role for the enzymatic site in both these activities. The finding that the plasminogen proactivator tolerated a dose of DFP, which completely inactivated the plasminogen activator, reveals that the active site is protected in the precursor protein.

A Neutrophil Immobilizing Factor Derived from Human Leukocytes

The neutrophil-immobilizing factor (NIF) derived from human leukocytes inhibited the random migration and chemotactic response of purified human neutrophils and eosinophils but not of monocytes. Concentrations of NIF sufficient to suppress mobility did not diminish phagocytic capacity or adherence to plastic Petri dishes of human neutrophils; the increased activity of the hexose monophosphate shunt associated with either phagocytosis or direct interaction with chemotactically active concentrations of kallikrein or C5a was also not suppressed. It is postulated that the in vivo role of NIF may relate to its ability to concentrate neutrophils in inflammatory foci without depressing their phagocytic potential or metabolic activation.

A neutrophil-immobilizing factor derived from human leukocytes. I. Generation and partial characterization

A factor has been derived from human leukocytes which irreversibly inhibits the response of human neutrophils to diverse chemotactic stimuli without impairing their viability. It is released by both polymorphonuclear and mononuclear leukocytes during incubation in acidic medium, after endotoxin exposure and subsequent incubation in low potassium medium, and during phagocytosis of particles. It is extractable from both leukocyte types and therefore must be preformed. This chemotactic inhibitor is completely separable from contaminating chemotactic activity in the crude supernatants, has a mol wt of 5000, and is inactivated by digestion with trypsin or chymotrypsin. It has been termed a neutrophil-immobilizing factor because it inhibits neutrophils directly and independently of the chemotactic stimulus, and has relatively little effect on human monocyte chemotaxis.

Immunologic Alterations in Bovine Serum Albumin Resulting from Partial or Complete Reduction and Alkylation

Purified monomer (4S) and dimer (7S) bovine serum albumin (BSA) were isolated from solutions of crystalline BSA by gel filtration. Mercaptoethanol reduction of BSA in buffered saline resulted in the appearance of only three sulfhydryl groups per molecule (3-SH BSA). Complete reduction in 8 M urea produced 34 free sulfhydryl groups per molecule (34-SH BSA). These BSA preparations were studied by optical rotatory dispersion, ultracentrifugation, quantitative precipitation and hemagglutination with homologous and heterologous antisera, and immunologic cutaneous reactions.

Significant distortion of the native BSA conformation by complete reduction and carboxymethylation (34-SH BSA) resulted in loss of precipitation with anti-native BSA. Partial unfolding of the native conformation of BSA resulted in greater precipitation with anti-native BSA and greater reactivity with anti-3-SH BSA hemagglutinins. This increase in antigenic reactivity was directly proportional to the loss of native α-helix content and accordingly was greater for 3-SH BSA than dimer native BSA. The augmented antigenic binding is felt to be due to an exposure of hidden antigenic determinants or the creation of new determinants associated with these conformational alterations.

Completely reduced carboxymethylated 34-SH BSA is a potent immunogen inducing high titers of non-IgG antibodies with passive hemagglutination and cutaneous anaphylactic activities, but no precipitating ability. Monomer 34-SH BSA does not precipitate or fix complement with any anti-BSA antisera, and therefore may be a univalent antigen. The strong Arthus reaction produced by the 34-SH BSA immunologic system despite a lack of precipitation and complement fixation in vitro suggests the possibility of antigenic aggregation in vivo.

A physiological approach to the assessment of disease activity in rheumatoid arthritis

A method is described for assessing the in vivo oxygen consumption and lactate production rates of human knee joints. It is based on the rate of fall of P(o2) and the rate of rise in lactate concentration in an intra-articular saline pool after interruption of the circulation to the joint with an arterial tourniquet. Studies in 5 control patients with degenerative joint disease and 29 patients with rheumatoid arthritis showed a 2- to 3-fold higher mean oxygen uptake rate and a 10- to 12-fold higher mean lactate appearance rate in the saline in the rheumatoid joints with severe disease compared to the control joints. These metabolic variables correlated with tissue metabolic demand as estimated in synovial biopsies. (133)Xe washout from the intra-articular space, which reflects joint circulatory flow, showed a 3-fold greater mean washout rate from the rheumatoid joints (48 studies) than control joints (7 studies) with extensive overlap between the two groups. (133)Xe washout rate correlated with knee joint inflammation estimated both clinically and histologically. After synovectomy in four patients, the operated knee showed a greater fall in lactate production than the opposite knee in three of these patients. Neither knee joint oxygen uptake nor (133)Xe washout rate changed significantly. Intra-articular corticosteroid injection (eight patients) resulted in decreased lactate production and a decreased (133)Xe washout rate in the injected knee and variable results in the untreated knee. Oxygen uptake again was unchanged after therapy.