Complement Activation ; Humans ; Thrombosis ; immunology

Hepatitis ; immunology ; Humans ; Liver Cirrhosis ; immunology ; Receptors, Complement ; blood

B cell activated co-receptor plays important roles in linkage of innate and acquired humoral immune responses. CD21 molecule in the co-receptor complex is a receptor for C3dg and CD19 molecule enhances BCR signal transduction. CD21 also expresses on the surface of follicular dendritic cells, which mediates the long-term maintenance of antigens and is indispensable for maintaining the memory of B cells. B cell activated co-receptor also has an effect on the negative selection of B cells reactive to autoantigens.
Animals ; Antigens, CD19 ; immunology ; Autoantigens ; immunology ; B-Lymphocytes ; immunology ; Humans ; Receptors, Complement 3d ; immunology ; Receptors, Immunologic

Proteins of the complement system are known to interact with many charged substances. We recently characterized binding of C1q and factor H to immobilized and liposomal anionic phospholipids. Factor H inhibited C1q binding to anionic phospholipids, suggesting a role for factor H in regulating activation of the complement classical pathway by anionic phospholipids. To extend this finding, we examined interactions of C1q and factor H with lipid A, a well-characterized activator of the classical pathway. We report that C1q and factor H both bind to immobilized lipid A, lipid A liposomes and intact Escherichia coli TG1. Factor H competes with C1q for binding to these targets. Furthermore, increasing the factor H: C1q molar ratio in serum diminished C4b fixation, indicating that factor H diminishes classical pathway activation. The recombinant forms of the Cterminal, globular heads of C1q A, B and C chains bound to lipid A and E. coli in a manner qualitatively similar to native C1q, confirming that C1q interacts with these targets via its globular head region. These observations reinforce our proposal that factor H has an additional complement regulatory role of down-regulating classical pathway activation in response to certain targets. This is distinct from its role as an alternative pathway down-regulator. We suggest that under physiological conditions, factor H may serve as a downregulator of bacterially-driven inflammatory responses, thereby fine-tuning and balancing the inflammatory response in infections with Gram-negative bacteria.
Binding, Competitive ; immunology ; Complement Activation ; immunology ; Complement C1q ; chemistry ; immunology ; metabolism ; Complement C4b ; analysis ; Complement Factor H ; chemistry ; immunology ; metabolism ; Complement Pathway, Classical ; immunology ; Escherichia coli ; immunology ; metabolism ; Humans ; Iodine Radioisotopes ; Isotope Labeling ; Lipid A ; immunology ; metabolism ; Liposomes ; immunology ; metabolism ; Protein Binding ; immunology ; Recombinant Proteins ; chemistry ; immunology ; metabolism ; Substrate Specificity

Neisseria gonorrhoeae (NG), as a pathogen of gonorrhea, is strictly limited to growth on the human host. In case of gonococcal infection, the body may recruit such inflammatory cells as neutrophils to resist the invasion of NG or initiate its adaptive immune response by antigen presentation to eliminate the pathogen. However, a series of immune escape mechanisms of NG make it difficult to clear up the infection. In the innate immune system, NG can not only secrete thermonuclease to degrade neutrophile granulocytes, inhibit respiratory burst to resist killing by neutrophils, activate NLRP3 to prompt the pyronecrosis of inflammatory cells, but also regulate the differentiation of macrophages to reduce the inflammatory response, combine with factor H to evade complement-mediated killing. NG infection can hardly give rise to effective adaptive immune response and immune memory, but can promote TGF-β production to inhibit Th1/Th2-mediated adaptive immune response, bind to CEACAM1 on the B cell surface to promote apoptosis in B cells, and combine with CEACAM1 on the T cell surface to inhibit helper T cell proliferation, which makes it difficult for B cells to produce high-affinity specific antibodies. With the increasing drug-resistance of NG, immunological studies may play a significant role in the development of novel therapies and effective vaccines against the infection.
Adaptive Immunity ; Antibodies ; immunology ; Antigens, CD ; immunology ; Cell Adhesion Molecules ; immunology ; Complement Factor H ; immunology ; Gonorrhea ; immunology ; Humans ; Immune Evasion ; immunology ; Immunity, Innate ; immunology ; Neisseria gonorrhoeae ; immunology

OBJECTIVETo investigate the effects of complement inhibiting component of Ephedra sinica on immunological inflammation following acute spinal cord injury (SCI) in rats.

METHODSThe complement inhibiting component of Ephedra sinica was isolated by multiple precipitation steps and thin layer chromatography, and then the activity was analyzed. Fifty healthy SD rats were selected and randomly divided into the control group and the experimental group, 25 in each group. Induction of SCI was performed following a modified Allen's weight-drop method. The complement inhibiting component from Ephedra sinica (15 mg/kg) dissolving in 5 mL normal saline was immediately administered by gastrogavage after SCI, once daily. Equal volume of normal saline was administered to rats in the control group by gastrogavage. Hematoxylin and eosin (H&E) staining and C3 immunohistochemical staining were performed in SCI tissue at 12 h, day 1, 3, 7, and 14 after SCI. C3 positive expressions and myeloperoxidase (MPO) activity were assessed. Intercellular adhesion molecule-1 (ICAM-1) mRNA expression level was evaluated by Real-time PCR technique.

RESULTSC3 positive expression, MPO activity, and ICAM-1 mRNA level were significantly weaker in the Ephedra sinica group than in the control group at all time points (12 h, day 1, day 3, day 7, and day 14 after SCI) (P < 0.01, P < 0.05).

CONCLUSIONSThere existed complement system activation following acute SCI. The complement inhibiting component of Ephedra sinica significantly reduced immunological inflammation after SCI, and played an important role in secondary SCI.

Animals ; Complement Activation ; drug effects ; immunology ; Complement Inactivating Agents ; pharmacology ; Ephedra sinica ; chemistry ; Inflammation ; immunology ; Rats ; Rats, Sprague-Dawley ; Spinal Cord Injuries ; immunology ; metabolism ; pathology

Autoantibodies ; Child ; Complement Factor H ; immunology ; Female ; Hemolytic-Uremic Syndrome ; immunology ; Humans

Of the many theoretical causes of rheumatoid arthritis(RA), the most widely held theory is the autoimmune mechanism. In order to clarify the clinical significance of the immunological tests in RA, we studied immunoglobulin and complement levels in sera and synovial fluids of 118 RA patients and the following results were obtained. 1) The levels of immunoglobulins were elevated in both serum and synovial fluid and this was more prominent in the seropositive cases than the seronegative ones. 2) The levels of C3 component were decreased in both serum and synovial fluid, while those of C4 were decreased only in synovial fluid. Serum C3 and C4 component levels were more decreased in the seropositive cases than the seronegative ones. 3) The immunoglobulin levels in serum (IgG, IgM and IgA) and synovial fluid (IgG and IgA) and the levels of C3, C4 component in serum were well correlated with the clinical forms of rheumatoid arthritis. 4) The IgA level in serum and IgM level in synovial fluid were more increased in the exacerbated cases than the chronic ones. 5) Serum IgG level was decreased after steroid medication over one month.
Arthritis, Rheumatoid/blood/*immunology/metabolism ; Complement 3/analysis ; Complement 4/analysis ; Female ; Human ; Immunoglobulins/analysis ; Immunologic Tests ; Male

Antibodies ; immunology ; Antibody Formation ; Complement C4b ; immunology ; pharmacology ; Diagnosis ; Graft Rejection ; diagnosis ; immunology ; Humans ; Kidney Transplantation ; immunology ; Peptide Fragments ; immunology ; pharmacology ; Transplantation, Homologous ; immunology

A 45-year-old woman with epidermolysis bullosa aquisita is presented. The clinical, histological, and immunopathological features were in keeping with the previous reports of this disease. The patient also had anti-basal cell cytoplasmic antibodies at a significant titer, which is considered an unusual finding associated with this disorder. Treatment with a moderate dose of corticosteroid was effective in controlling the bullous lesions
Autoantibodies/*analysis ; Complement C3/analysis ; Cytoplasm/*immunology ; Epidermis/*immunology ; Epidermolysis Bullosa Acquisita/diagnosis/*immunology ; Female ; Humans ; Middle Aged