Immunological communications最新文献

The acute phase of inflammation is characterized by numerous changes in blood composition, perhaps the most dramatic of these being the elevation of C-reactive protein levels. C-reactive protein (CRP) is known to bind to molecules containing phosphocholine-substituents following reaction with Ca2+ ions. Luminescence energy transfer (LET) has been used effectively to study the Ca2+ and Mg2+ binding properties of many proteins by employing appropriate lanthanides (III). We have used Tb3+ as an isomorphous analogue to study Ca2+ binding to CRP. Energy transfer occurs effectively and demonstrates the importance of aromatic residues (viz., tyrosine and tryptophan) in the binding of Tb3+. The binding of Tb3+ is remarkably dependent on the pH and indicates the requirement of a deprotonated residue in the pH range 6.4 +/- 0.2 for effective Tb3+ binding. A 50-fold molar excess of Ca2+ is sufficient to displace the Tb3+ suggesting that Tb3+ is bound with greater affinity to CRP than the natural analogue Ca2+. We propose that Tb3+ (by inference Ca2+) binding takes place near the CRP subunit disulfide bond, where two histidine residues are present. The pH dependency of Tb3+ binding is best explained by the deprotonation of a histidine residue(s) in CRP.

Previously, we have shown by radioimmune antibody binding studies that immunization with each of the five synthetic antigenic sites of sperm-whale myoglobin (Mb), in their free form (i.e. not coupled to a carrier), resulted in the formation of antibodies that bound specifically to Mb and exclusively to the peptide that was used in immunization. In the present series of studies we have immunized separate groups of Balb/cByJ mice with different amounts of each of the free synthetic antigenic sites so as to determine the optimum immunizing dose for eliciting serum antibodies that bind specifically to Mb. The synthetic peptides corresponded to: Site 1 (peptide 15-22), Site 2 (peptide 56-62), Site 3 (peptide 94-100), Site 4 (peptide 113-120, and Site 5 (peptide 145-151). The dose range of each of the antigenic sites used in immunization was from 6 micrograms to 100 micrograms. Radioimmune antibody binding studies indicated that there is an optimal immunizing dose for each of the five antigenic sites which was smaller than anticipated. The significance of these findings is discussed.

Rabbits were immunized with a cytosolic fraction prepared from human adenocarcinoma cells of the colon (GW-39). The antibodies obtained were analyzed using crossed immunoelectrophoresis and were found to precipitate 23 distinct antigens in the cytosolic fraction from colon tumor cells. After preabsorption with human serum and plasma as well as acetone powders prepared from 2 normal human tissues and 4 normal hamster tissues, 1 major immunodominant cytosol antigen (CA-3) and two less intense immunoprecipitin peaks (CA-1 and CA-5) remained detectable by the crossed immunoelectrophoretic method. The preabsorptions with normal tissues were sufficiently complete to remove anti-carcinoembryonic antigen antibodies and showed that antigens CA-1, CA-3 and CA-5 are immunologically distinct from carcinoembryonic antigen. Indirect immunofluorescence localization studies with preabsorbed anti-cytosol antibodies and FITC-conjugated second antibody showed that these antigens were expressed in the cytoplasm and at the cell surface in several human colon tumor cell lines, their subclones and in primary colon tumor specimens.

The influence of zinc on the in vitro antibody response to antigen or mitogen stimulation was studied by adding various concentrations of ZnCl2 to cultures of spleen cells stimulated with sheep erythrocytes, trinitrophenyl-lipopolysaccharide or with the polyclonal B cell activator E. coli lipopolysaccharide (LPS). Addition of ZnCl2 in concentrations ranging from 10(-8) or 10(-7) to 10(-5) M increased the specific antibody response to antigens or the polyclonal antibody synthesis induced by stimulation with LPS, when the response of the assayed population in the control cultures without ZnCl2 was low, as observed in cultures without 2-mercaptoethanol (2-ME). However, in cultures supplemented with 2-ME, the potentiating effect of ZnCl2 diminished or disappeared or even the antibody response was inhibited. Higher concentrations of ZnCl2 markedly depressed (5 X 10(-5) M) or abolished (10(-4)) the in vitro induced antibody response in all cultures. The various mechanisms which could mediate the effects of zinc are discussed.

Decreased lung clearance of Staphylococcus aureus has been reported in mice homozygous for the cribriform degeneration (cri) autosomal recessive mutation. In the present study, the phagocytic capacities of alveolar and peritoneal macrophages were quantitated by applying kinetics of the first order reaction criteria. The characteristics of the pulmonary and peritoneal mononuclear cell populations from mutant and control mice were indistinguishable. The kinetic assays revealed decreased phagocytosis work in both alveolar and peritoneal macrophages from cri/cri mice. The results lend support to this mutation as a possible model system to study the early stages of lung disease physiopathology in cystic fibrosis.

This study was conducted to determine if hypothyroidism has an effect on humoral immunity in immature male chickens. Two week old Single Comb White Leghorn male chicks were used as experimental animals. Two experiments were conducted using different methods to induce hypothyroidism. In Experiment 1, birds were surgically thyroidectomized (Tx group) and in Experiment 2, hypothyroidism was induced by supplementing the feed throughout the experiment with 0.1% propylthiouracil (PTU group). Antibody production against sheep red blood cells (SRBC) (thymus-dependent antigen) and Brucella abortus (BA) (thymus-independent antigen) was tested at 4 weeks of age. Serum concentrations of T4 and T3 were measured in birds from each treatment group at 5 and 9 weeks of age. Body weights were recorded and birds were then autopsied and thyroid gland weights were measured. Hypothyroidism was successfully induced in both Tx and PTU birds, as reflected by significant reduction in body weights in both groups, enlargement of thyroid glands in PTU birds and absence of thyroid glands in Tx birds. Though T4 and T3 were reduced in sera of treated birds, considerable amounts of these hormones were detected. Hypothyroidism did not seem to have profound or consistent effects on antibody production against SRBC or BA. The possibility that thyroid hormones play a role in antibody production was not ruled out. However, it was suggested that within the physiological range of thyroid gland activity, thyroid hormones may not significantly regulate antibody production.

Experimental allergic encephalomyelitis (EAE) is an experimental, T-cell dependent, autoimmune disease of the central nervous system that can be induced in most mammals by the injection of myelinated neural tissue in complete Freund's adjuvant. Relatively small doses, 10(4.6) Units/kg, of rat interferon (IFN), specific activity 10(7.6) Units/kg, delayed the onset of the disease and significantly ameliorated the severity of EAE symptoms observed in Lewis rats. Injection of IFN at 10(5.6) U/Kg suppressed hind limb paralysis in 70 to 80% of the rats.

Antisera to human brain (AHBS) and human thymocytes (AHTS) were produced in rabbits and selectively absorbed to render them specific for T cells. After absorption AHBS, but not AHTS, lost most of its cytotoxic activity against T cells. Absorbed AHBS bound up to 95% of peripheral blood T lymphocytes as detected by indirect immunofluorescence and inhibited up to 46% of the lytic activity of AHTS; however, it was incapable of inhibiting the E-rosette formation of T lymphocytes. All 10 samples of human peripheral blood lymphocytes, pretreated with AHBS, were significantly suppressed in their response to antigens, but fewer samples were affected in their response to mitogens and to allogeneic stimulation, indicating diversity in the nature of the receptors involved in the cellular responses.

Cyclic AMP-dependent protein kinase activity has been measured in DEAE-cellulose elution profiles of highly enriched murine splenic T and B Lymphocytes. B Lymphocytes were found to contain about 10% of the amount of enzyme activity associated with T lymphocytes and several non-lymphoid tissues. Cyclic AMP-independent casein kinase activities were equivalent in T and B lymphocytes. Lymphocytes contained predominantly type I isozyme as opposed to several non-lymphoid tissues which all contained predominantly the type II form.

Rat alloantigens expressed on normal hepatocytes have been utilized in a cell "panning" procedure to mediate the haplotype-specific adherence of collagenase-isolated hepatocytes to antibody-coated polystyrene dishes. A polyvalent F344 anti-WF alloantiserum was prepared by immunizing F344 rats with WF tissue. The alloantibody IgG purified from the alloantiserum, when reacted with either WF or (WF X F344)F1 hybrid rat hepatocytes, caused the adherence of these hepatocytes to bacteriological-grade polystyrene dishes coated non-specifically with a xeno-antibody, rabbit anti-rat IgG. Similarly-treated hepatocytes of the F344 strain, which lack WF alloantigenic determinants, failed to be adsorbed above background level to the coated dishes.