Experimental diminution fo splenci function by selective embolization of the splenic artery

The splenic artery was occluded by the selective injection of Amicar-mixed clot or Gelfoam in 18 dogs. The dogs were sacrificed at 24 hours, two weeks and two months. Angiography was done before and after embolization, three hours after embolization and prior to sacrifice. White blood counts and hematocrit values were evaluated weekly in the dogs sacrificed at two months. The results of this study reveal differences in the effects of the two embolic materials. Because Amicar-mixed clot was partially lysed in the first several hours and also pushed peripherally, the depression of hematologic function seen with its use was transient and most spleens returned to a relatively normal gross and histologic appearance. With Gelfoam, although the embolic material was also pushed peripherally into the branches of the splenic artery in several of the dogs, the depression of hematologic function was prolonged, and moderate splenic parenchymal fibrosis was seen. The areas between the bands of fibrosis appeared normal. The results indicate that selective embolic occlusion of the splenic artery and its branches may offer a method of depressing splenic function in patients who are not candidates for splenectomy.

The effect of heparin on the affinity chromatography of plasminogen. Demonstration of heparin-plasminogen interaction

Evidence is presented that heparin binds rabbit plasminogen types I and II under affinity chromatographic conditions using the single stage technique earlier described (Hatton, M.W.C. and Regoeczi, E. (1974) Biochim. Biophys. Acta 359, 55-65). Thus, the affinity of types I and II for Sepharose-lysine is markedly increased in the presence of heparin and elution by epsilon-aminohexanoic acid requires a steeper gradient to recover the plasminogen types. Furthermore by adding sufficient epsilon-aminohexanoic acid to non-heparinised plasma to suppress plasminogen affinity, the presence of heparin is shown to encourage binding of plasminogen (type II more so than type I) to the gel. However, the heparin effect is quickly reversed by washing the column with 0.5 M NaCl prior to elution by epsilon-aminohexanoic acid. No evidence of a stable plasminogen-heparin complex has been found from gel filtration studies and any interaction between plasminogen and heparin probably only takes place when heparin is bound to an affinity site. Studies with 35-S-labelled heparin have shown the mucopolysaccharide to bind to the free amino group of Sepharose-lysine and Sepharose-cadaverine and to be displaced by 0.5 M NaCl elution but not by 0.1 M epsilon-aminohexanoic acid. The plasminogen types produced from heparinised plasma are free from heparin and closely resemble preparations from non-heparinised plasma when compared by polyacrylamide gel electrophoresis, Sephadex gel filtration and arginine esterase activity after urokinase activation.

Studies on the control of antibody synthesis. IX. Effect of boosting on antibody affinity

The effect of boosting on antibody affinity was studied in a haptenic system. Generally, boosting results in the prompt synthesis of high affinity anti-hapten antibody. However, repeated boosting frequently leads to a decrease in the amount and affinity of the serum antibody. Repeated boosting with hapten on a carrier different from that used for priming selectively stimulates synthesis of the highest affinity anti-hapten antibody and does not result in a decrease in affinity. Priming with soluble antigen without adjuvants results in the synthesis of low affinity antibody. After such priming, boosting stimulates low affinity antibody synthesis and repeated boosting leads to a moderate increase in antibody affinity.

A comparison of the Farr technique with equilibrium dialysis for measurement of antibody concentration and affinity

The Farr technique has been compared with equilibrium dialysis in regard to its ability to measure antibody concentration and affinity. An excellent qualitative agreement between the two techniques was obtained. Quantitatively, the Farr technique tended to underestimate antibody concentration and overestimate antibody affinity. It is likely that these observations are due to the failure of some low affinity antibodies to bind hapten under the conditions of the Farr assay.

Isolation, subunit structure, and proteolytic modification of bovine factor VIII

A new method has been described for the isolation of factor VIII. The method results in a high yield of factor VIII that is homogeneous by several different criteria. The purified protein is very stable and is not dissociated in the presence of 1 M NaCl or 0.25 M CaCl2. The highly purified protein is readily activated and inactivated by various proteolytic enzymes, such as thrombin, plasmin, and trypsin. The molecular events that lead to the activation reaction, however, have not been established.

Enhancement of nitroblue tetrazolium dye reduction by leukocytes exposed to a component of complement in the absence of phagocytosis

Enhancement of in vitro nitroblue tetrazolium dye reduction by human polymorphonuclear leukocytes may be mediated by a low molecular weight fluid phase component of the complement system. This occurs in the absence of phagocytosis and is associated with an increase in leukocyte hexose monophosphate shunt activity. The stimulatory component may be generated by activating the alternate complement pathway in serum, and shares many of the properties of human C5a. Thus, the enhanced spontaneous reduction of nitroblue tetrazolium by leukocytes from patients with bacterial sepsis may not necessarily be due to the phagocytic activity of these cells, but rather may occur as a consequence of in vivo complement activation by either intact microorganisms or their products.

Comparative effects of proteinase inhibitors, plasminogen antiactivators, heparin and acetylsalicylic acid on the experimental disseminated intravascular coagulation induced by thormbin

In an experimental study in the rabbit, the modifications of some haemostasis parameters (platelet count, platelet retention and aggregation, platelet factors 3 and 4, platelet and plasma plasmin inhibiting activities, fibrinogen and other plasma factor levels, FDP), and histological findings are compared in both the normal animal and the animal with disseminated intravascular coagulation (DIC) induced by thrombin perfusion after administration of fibrinolytic inhibitors (plasminogen antiactivators and proteinase inhibitors). In the normal animal, the administration of fibrinolytic inhibitors is followed by haemostatic changes similar to those found in thrombophilic states. The modifications are more pronounced with plasminogen antiactivators than with proteinase inhibitors. In the animal with DIC, the administration of fibrinolytic inhibitors enhances the haemostatic and the biological disorders produced by thrombin perfusion. The effect of the plasminogen antiactivators is even more evident. The preventive administration of heparin reduces or abolishes the biological and histological disorders induced by thrombin; its beneficial effect is considerably reduced when thrombin is combined with fibrinolytic inhibitors. The administration of acetylsalicylic acid appears to be ineffective for the prevention of haemostatic and histological changes induced by thrombin perfusion.

Selective roles of thymus-derived lymphocytes in the antibody response. II. Preferential suppression of high-affinity antibody-forming cells by carrier-primed suppressor T cells

Passive transfer of thymocytes and spleen cells from donors primed with keyhole limpet hemocyanin (KLH) caused significant decrease in the average avidity of anti-DNP antibodies produced by direct and indirect PFC in the recipients in both primary and adoptive secondary antibody responses against DNP-KLH. The analysis of the avidity distribution of antibodies produced by plaque-forming cells (PFC) indicated that the observed decrease in the average avidity is primarily due to the selective loss of high avidity subpopulation of PFC leaving low avidity subpopulation relatively unaffected. The degree of suppression in antibody avidity did not correlate with the reduction in the number of PFC, and thus causing the "shift" of avidity distribution of PFC to the low avidity end. These results indicate that the "maturation" of antibody in the T-cell-dependent antibody response is influenced by the carrier-specific suppressor T cells with respect to the emergence and selection of B cells having high affinity receptors for hapten. It is suggested that B cells binding antigen with high affinity receptors would be more easily affected than those with low affinity receptors by specific suppressor T cells which are capable of reacting the carrier portion of the same antigen.

Binding studies on isoelectrofocused fractions from a DNP antibody population

Preparative liquid isoelectric focusing has been used to isolate antibody fractions of restricted heterogeneity from typically heterogeneous anti-DNP antibody populations. The focusing distributions of anti-DNP antibody isolated from different rabbits and from different bleed periods (separated by 120 days) of the same rabbit were qualitatively very similar. All antibody preparations contained major components focusing in the pH ranges 7.5–8.5, 6.4–6.6, 5.8–6.1, and 5.3–5.7. However, demonstrable quantitative differences in the relative proportions of the pH 6.4–6.6 component and the pH 5.3–5.7 component were seen in comparing the focusing distributions of antibody isolated from the two bleed series of the same rabbit.

Three of the focused fractions from the later bleed period were refocused over appropriate pH ranges yielding components considerably restricted in charge heterogeneity. Binding parameters determined for the refocused fractions were indicative of functional homogeneity. There was no correlation between binding affinity and antibody electrical charge. Additionally, there was no consistent relationship between the spectral properties (extinction coefficients and maximum quench values) of the refocused fractions and their relative affinities.

The qualitative similarities and the quantitative differences observed in the focusing distributions of antibody isolated from different bleed series of the same rabbit are consistent with a selectional theory of antibody production. The results of binding experiments suggest a somewhat anomalous role for antibody tryptophan in the binding of dinitrophenyl ligands.

Affinity labelling of isoelectrofocused fractions from a DNP antibody preparation with the photoactive labels 2,4-dinitrophenyl-1-azide and 2,4-dinitrophenyl-epsilon-aminocaproyldiazoketone

Isoelectric (I.E.F.) fractions from two DNP antibody preparations have been affinity labelled with the photo-active labels 2,4-dinitrophenyl-1-azide (DNP—N₃) and 2,4-dinitrophenyl-ε-aminocaproyl diazoketone (DNP—EACDK). The ratios of heavy to light chains labelled for I.E.F. fractions A, B and C of antibody preparation A-2, labelled with DNP-N₃, were 4.5, 3.1 and 2.4 respectively. In excellent agreement with these results were the ratios found for the labelling of I.E.F. fractions A, B and C of a second antibody preparation A-1 pool I, which were 4.4, 3.8 and 2.0 respectively. A second fraction of DNP antibody preparation A-1 (pool II) was isoelectrically focused, and the I.E.F. fractions A′, B′ and C′ were affinity labelled with the label DNP—EACDK. The ratios of heavy to light chains labelled for the I.E.F. fractions A′, B′ and C′ were 3.4, 0.12 and 5.6 respectively. Mass spectral analyses of the predominant radioactive fraction isolated from the nagarse digestion of the DNP-N₃ labelled heavy chains from I.E.F. fractions A-2 A and A-2 C indicated that fraction A was labelled primarily on a phenyl-alanine residue and that fraction C contained most of the label on an alanine residue. The labelling results support the view that the combining sites of anti-DNP antibodies are distinct and differ substantially and the `characteristic' heavy/light chain ratio of 2 to 4 represents an average of individually homogeneous sites which are labelled by a given affinity reagent exclusively on either light or heavy chains but not both.