Biomedical subjects
Publications and source records attributed to H Bazin.
Two lines of mice selected for genes controlling the character "quantitative agglutinin production" to heterologous erythrocytes were immunized orally by the intragastric administration of sheep red blood cells (SRBC). The quantity of circulating IgA anti-SRBC and the numbers of splenic plaque-forming cells of IgA and IgM classes were related to the genetic status of the animal lines.
In earlier studies we found that normal rat macrophages, preincubated at 37 degrees C with the serum of syngeneic rats immune to Schistosoma mansoni, strongly adhered to S. mansoni schistosomules whereas no significant adherence was induced with serum from normal rat. Using 51 chromium release assay, it now proved that immune serum-incubated macrophages lysed the schistosomules in 18 h. Absorption experiments and ultracentrifugation of the immune serum showed that immune complexes containing specific IgE antibody against S. mansoni and soluble parasite antigens induced macrophage adherence and cytotoxicity. Using various labeling techniques, the binding of aggregated rat IgE to the macrophage surface at 37 degrees C is evident in conditions where endocytosis is neglible. The binding of immune complexes containing IgE antibody to S. mansoni elicits dramatic ultrastructural changes in the macrophage and an increase of its lysosomal enzymes together with specific lytic activity for the schistosomules. The parallel development of immune serum-induced macrophage adherence or cytotoxicity with the level of circulating IgE antibody to the parasite in correlation with the development of immunity in the rat, suggests that this new mechanism of macrophage activation could play a role in immune effector mechanisms against S. mansoni. Therefore, IgE acts as a humoral mediator of cellular immunity.
A direct solid phase radioimmunoassay for the measurement of total serum IgE in the rat has been developed. The assay is very sensitive with a lower limit of detection of 5 ng/ml. The intra and interassay reproducibility proves to be very acceptable and the specificity is demonstrated by looking at the interferen-e by other immunoglobulins. Preliminary results on total serum IgE levels are given.
Malignant ileo-caecal immunocytomata, which secrete immunoglobulin, frequently arise spontaneously in LOU/C/Wsl rats. The tumors are confined to the ileo-caecal region and could originate either in the wall of the caecum or in the ileo-caecal lymph nodes. After excision of the ileo-caecal lymph nodes, the incidence of the type of tumor was found to be reduced significantly. The results strongly suggest that the first cells to undergo malignant transformation are located in the ileo-caecal nodes.
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Graft hypoperfusion secondary to widespread vascular occlusion by recipient-derived platelet aggregates may be a major determinant of hyperacute cardiac allograft rejection in the rat. Since a hereditary platelet aggregation defect, attributed to decreased platelet levels of serotonin and adenine nucleotides and a depressed release reaction, has been described in the fawn-hooded rat strain, the effects of this intrinsic platelet function defect on the time course and morphologic features of hyperacute rejection have been evaluated. A series of nine heterotopic ACI cardiac allografts in fawn-hooded recipients actively immunized with ACI skin grafts were studied. Functional rejection with asystole was observed in all allografts from 8 to 40 minutes posttransplantation. Widespread platelet aggregation, endothelial cell destruction, interstitial widening, and focal myocardial alterations consistent with ischemic damage characterized all allograft. This study indicates that the platelet aggregation defect described for the fawn-hooded rat strain is one that does not alter the time course of the morphologic features of hyperacute cardiac allograft rejection, and thus this platelet aggregation abnormality has no essential role in the pathogenesis of this type of tissue damage.
We have measured the levels of IgG1, IgG2a, IgG2c, IgA and IgM in the serum of normal rats, and at various times after infection or re-infection with Nippostrongylus brasiliensis, in order to compare these responses with previously measured IgE levels. The results we have to report are that while the levels of the various immunoglobulin classes or subclasses are elevated to a greater or lesser extent, the increments are modest by comparison with the great elevation of total IgE.
Serum IgE levels were measured by radioimmunoassay in four strains of rats, before and after infection by Schistosoma mansoni. Differences were observed in basal IgE levels, depending on the strain considered. Serum IgE rose 10--20 days after infection and the maximum level, between days 30 and 50, ranged from 14 to 60 times the basal level. One of the most characteristic features of IgE production in rat schistosomiasis was the persistence of high IgE levels for a long time after rejection of the worms.
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The possibility that IgE is a secretory immunoglobulin has been examined by studying the tissue and cellular localization of IgE in rats infested with the enteric parasite, Nippostrongylus brasiliensis. The lamina propria of the small intestine and the colonic and pulmonary mucosal surfaces contained numerous anti-IgE-binding cells, but these were shown to be mast cells and not plasma cells. The major site of IgE synthesis was the regional lymph node of the small intestine, the mesenteric node, which contained large numbers of IgE-secreting plasma cells. Smaller numbers of IgE-secreting plasma cells were also found in the axillary node, which drained the site of larvae injection. Peyer's patches, the intrapulmonary bronchial lymphoid tissue and the spleen contained few, if any, IgE-secreting plasma cells. The significance of the IgE which was readily demonstrated in germinal centers of the mesenteric lymph nodes, the Peyer's patches and the axillary lymph nodes, is not known. In contrast to the infested animals, the lymphoid organs of normal rats rarely contained any IgE-CONTAINING CELLS; An unexpected observation was that mast cells in mucosal organs appear to contain intracellular IgE, differing in this respect from connective tissue mast cells. Mast cells lying between epithelial cells, the "globule leukocytes", also appear to contain intracellular IgE, and it is suggested that such cells may be responsible for the presence of IgE in exocrine secretions. This study does not support the suggestion that IgE is a secretory immunoglobulin with a physiology analogous to that of IgA.
The stimulatory as well as the inhibitory capacity of alloantisera has been investigated with respect to rat mast cell functions. Alloantibody against alloantigens coded for by the major histocompatibility (H-1) gene region promoted histamine release from purified LEW mast cells. This process was found to be complement-independent but demonstrated an absolute requirement for calcium. Pretreatment of mast cells with anti-H-1 antisera in the absence of calcium markedly suppressed the IgE-dependent histamine release challenged either by antigen or by anti-IgE antibody. The alloantisera, however, did not interfere with the ability of compound 48/80-associated histamine liberation. Additionally, antibodies specific for H-1 antigens were highly effective in inhibiting the binding of IgE to the mast cell surface. Alloantisera absorbed with erythrocytes lost their capacity to block mast cell functions. Based on these data the possible ralationship between H-1 alloantigens and the IgE receptor on the mast cell surface is discussed.
Partial amino acid sequences have been determined for several kappa-type light chains prepared from sera or urine of inbred LOU/C/Wsl rats bearing plasma cell tumors. Comparison of these sequences with those of human, rabbit, and mouse kappa-chains available in the literature indicates that the constant region of rat kappa-chains shows more amino acid sequence homology to that of the mouse kappa-chain than to human and rabbit kappa-chains, a result expected from the phylogenetic relationship of the species compared. Examination of the N-terminal amino acid sequences indicated that the variable regions of rat kappa-chains can also be classified into subgroups according to degree of sequence homology in a manner similar to that done for kappa-chains of other species (e.g., human, rabbit, and mouse). However, the prototype amino acid sequences of kappa-chain variable region subgroups of the rat were not homologous to those of other species including the closely related mouse. The implications of this observation with respect to the genetics and evolution of immunoglobulins are discussed.
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The bacterial strain L.16.1 isolated from coastal waters polluted by oil-waste, close to the genus Alcaligenes, utilizes preferentially alkanes with a carbon number greater than 9. Sugars and amino-acids cannot serve as carbon source to this bacterium. Cells grown on hydrocarbon the chain length of which ranges from C10 to C18 exhibit very high yield (98%) with a growth rate of 0.47. From our studies it appears that strain L.16.1 is strictly dependent on the presence of the Na+ ion and that this Na+ dependence can be seen at each level of the physiological activity. Alkane-grown cells show morphological features namely disc shaped cytoplasmic vesicles (6-8 per cell). Such vesicles are to be regarded as a consequence of the very high lipid content (twice the standard) which characterizes these cells. Additional lipids belong essentially to the nonsaponifiable fraction (20 times more in hexadecane grown cells); on the contrary, the phospholipid content at both qualitative and quantitative points of view does not depend on the nature of the growth substrate.
The growth of the marine bacterium (L.16.1) is strictly dependent on the presence of well-defined NaCl concentrations (100 mM on alkanes and 75 mM on acetate, pyruvate or propionate) in the medium. L.16.1 cells undergo lysis on transfer from high to low ionic environment. This lytic phenomenon, which can be prevented by the presence of Na+ or divalent cations, appears to be due to the loss of Mg++ and Ca++ by the cells. Evidence for this hypothesis is provided by the assays of intracellular and extracellular Na+, K+, Mg++ and Ca++ concentrations. The maintenance of the cell integrity of the organism does not depend on the medium osmolarity, since osmotic compounds such as sucrose, glycerol or mannitol cannot prevent lysis. All of the ions which can maintain the cell integrity are not likewise able to keep viability; this has been found to be a function of Na+ concentration (70% survival after 24 hours in 400 mM NaCl, only 10% in 50 mM MgSO4).
The oxidation of exogenous hexadecane by cells of strain L.16.1 is a function of intracellular and extracellular Na+ and K+ concentrations. The cells which lost their Na+ as a result of washing in the absence of sodium chloride oxidize hexadecane at a very low rate. Washings in the absence of Mg++ and Ca++ do not result in a similar decrease of the respiratory activity. The latter cannot be maintained--or restored after decrease--by the divalent cations which are active in preventing cytolysis (see the preceding paper). A possible explanation for this Na+ dependence could lie in a particular role played by Na+ inthe cytoplasmic membrane and in some function related to the oxidative activities of the cell membrane. From other studies carried out with ionic detergents it was observed that growth and respiratory activity are inhibited by very low concentrations of these compounds contrary to non ionic detergents which can serve as growth substrates and are oxidized like hexadecane or acetate. It is concluded that the bulk of our results could best be accounted by assuming that the membranes of halophilic bacteria are organized according to a specific organization scheme.
Reaginic antibody synthesis following parenteral and/or oral administration of ovalbumin and Bordetella pertussis organisms as adjuvant has been evaluated in LOU/M/Wsl inbred rats. These rats are able to produce high reaginic antibody serum levels after intraperitoneal injection of this antigen. Primary oral administration of ovalbumin doses between 10 and 100 mg with Bordetella pertussis organisms given as adjuvant by the intraperitoneal or the oral route led to characteristic reagnic responses. Secondary reaginic responses were obtained by oral administration of ovalbumin without any adjuvant in animals sensitized by the oral or the intraperitoneal route. A hundred micrograms of ovalbumin was enough to induce reaginic responses but more constant and higher reaginic levels were obtained with a 50 mg dose in the experimental model employed.