Interactions among structural proteins of varicella zoster virus.

Varicella zoster virus tegument components include the regulatory proteins IE4, IE62, IE63 and the ORFI0 protein, a protein kinase (ORF47) and an abundant protein encoded in ORF9 which is the homolog of HSV VP22. The kinase is able to phosphorylate IE62 and the ORF9 protein specifically in viral particles. We show that interactions among these proteins are, at least in part, dependent on the presence or absence of phosphate groups and we suggest models for tegument formation and for its dissolution in the infected cell.

Interaction of antibody with Forssman antigen in guinea pigs. A mechanism of adaptation to antibody- and complement-mediated injury.

Forssman antigen is a glycosphingolipid with antigenic specificity determined by extra-membrane haptenic sugars similar to blood group antigens and antigens that are the main barrier to xenogeneic organ transplantation. Herein, we describe the localization of Forssman antigen in guinea pig lungs and kidneys and the consequences of its interaction with antibodies in vitro and in vivo (Forssman reaction). Exposure of cultured guinea pig aortic endothelial cells to Forssman antibodies induced rapid redistribution of antigen-antibody complexes at the cell surface, followed by shedding that occurred by blebbing of plasma membrane as vesicles or fragments, and was associated with disappearance of antigen from the cell surface (antigenic modulation). Guinea pigs surviving frequent intravenous infections of increasing amounts of antibodies, for a total of 20 to 40 lethal doses, developed a partial or complete adaptation to generalized Forssman reaction, and adaptation was associated with partial or complete modulation of Forssman antigen at the surface of the pulmonary and, in minor degree, renal endothelial and epithelial cells. These findings support the hypothesis that modulation of endothelial carbohydrate antigens contributes to adaptation of highly vascularized organs exposed to tolerable levels of allo- or xenoantibodies.

The effect of SRI 63-675, a competitive platelet-activating factor receptor-antagonist, in the generalized Shwartzman reaction.

Evidence indicates a role for platelet-activating factor (PAF) in endotoxin (LPS)-induced shock. To determine its involvement in LPS-induced intravascular coagulation, we assessed the efficacy of SRI 63-675, a specific PAF receptor antagonist, to prevent fibrin deposition in the various organs of New Zealand White rabbits 4 h after two intravenous doses of LPS (100 micrograms/kg), spaced 24 h apart. SRI 63-675 significantly lowered peak tumor necrosis factor levels after LPS challenge. Administration of SRI 63-675 around either the first (150 mg/kg) or second LPS dose (120 mg/kg), however, did not prevent coagulation. The unexpected high mortality after combined administration of SRI 63-675 and LPS precluded assessment of PAF inhibition around both LPS doses on coagulation. Sole administration of SRI 63-675 induced rapid and transient changes in peripheral blood cell counts, and blood pressure and heart rate suggestive of intrinsic PAF-like activity. Although some other intrinsic toxic effect of SRI 63-675 cannot be ruled out, it is suggested that endotoxin may have primed the rabbit to the lethal, PAF-like, effects of SRI 63-675.

Transfer of experimental autoimmune thyroiditis by in situ perfusion of thyroids with immune sera.

The role of autoantibodies in the pathogenesis of autoimmune thyroiditis (AT) still remains poorly understood. Serum transfer experiments in experimental AT (EAT) and spontaneous AT (SAT) animal models frequently did not succeed or only resulted in minor thyroid lesions. The inconsistent results may have arisen because of technical problems inherent in serum transfer, the major of which is to obtain high enough concentrations of autoantibodies over long enough periods at the potential site of tissue injury. An attempt was made to circumvent this hurdle by repeated in situ perfusions of the rabbit thyroid via the superior thyroid artery. In situ perfusion of rabbit thyroids with high-titered homologous sera reactive with saline thyroid extract indeed led to thyroiditis characterized by granular deposits of rabbit IgG and C3 in the thyroid follicular basal laminae, cellular infiltrates consisting of mononuclear cells and granulocytes, destruction of the thyroid follicular architecture, and focal fibrosis. Perfusion with control sera lacking thyroid-reactive antibodies did not lead to thyroid lesions. These results demonstrate that humoral antibodies can induce severe AT comparable to actively induced thyroiditis.

Role of late complement components in experimental autoimmune thyroiditis.

Availability of a line of rabbits deficient in the sixth complement component (C6-D) made it possible to evaluate the role of the terminal complement complex (TCC) in the development of experimental autoimmune thyroiditis (EAT) of the rabbit. Immunization with saline extract of homologous thyroid, known to be composed predominantly of thyroglobulin, led in normocomplementemic (NC) rabbits to severe thyroiditis, with cellular infiltrates occupying 50-95% of the thyroid, and to minimal or moderate thyroiditis, with 1-35% of thyroids infiltrated in C6-D rabbits. Cellular infiltrates consisted predominantly of mononuclear cells with appreciable numbers of granulocytes. Destruction of thyroid follicles was extensive and diffuse in NC rabbits, but it was only minimal and focal in C6-D rabbits. Immunohistology revealed in both groups of rabbits deposits of IgG and C3 along follicular basal laminae. In addition, NC rabbits showed deposition of C6 and MAC in thyroid follicles. These results suggested that TCC is necessary for the development of fully expressed, severe EAT; simultaneously, however, they showed that a significantly reduced EAT can develop without TCC. Administration of NC but not of C6-D rabbit serum to C6-D rabbits resulted in a significant increase in the severity of EAT. It was also shown that C6-D rabbits have "normal" T-cell activity, since they developed experimental autoallergic encephalomyelitis as readily as NC rabbits. Therefore, it is likely that development of EAT is indeed impaired by the C6 deficiency in rabbits. The requirement for TCC observed in this study may be relevant to the understanding of the pathogenesis of Hashimoto's thyroiditis, in which thyroid tissue was recently shown to contain TCC deposits.

Glomerulonephritis in NZW kidneys grafted into NZB/W mice.

After left nephrectomy, 3 10-week old NZB/W mice received orthotopic grafts of kidneys from parental NZW mice of the same age. At autopsy conducted at the age of 33-38 weeks, glomerulonephritis of similar extent was noted in the recipients' own and in the grafted kidneys. Also, very similar granular deposits of immunoglobulins and complement were demonstrated in these kidneys. It was concluded that the absence of glomerulonephritis in NZW mice cannot be attributed to the refractoriness of their kidney to this disease.

Studies on immunological tolerance induced in mice by kidney allografts.

(C57BL/6 x A/J)F1 murine recipients of DBA/2 kidney allografts developed tolerance to DBA/2 tissues, which was measured by observation of growth of a DBA/2 tumor. Eleven, 14 and 18 days after inoculation, the size of the tumor was considerably larger in kidney-grafted than in nongrafted animals. Still, the susceptibility of grafted animals to the tumor did not equal the susceptibility of the DBA/2 mice syngeneic with the tumor. Removal of the renal graft left the recipients with significant tolerance which, however, was weaker than that of the mice in which the kidney graft was left undisturbed. In parabiosis experiments, it was noted that the size of the DBA/2 tumor was equal in the partner which received the DBA/2 kidney graft and in the partner which was not grafted. These experiments rather clearly showed that the tolerance studied was of an 'infectious' type and that it was apparently transferred by some suppressing factor(s) present in the circulation.

Humoral transplantation antibodies play a role in protracted rejection of murine renal allografts.

Murine renal allografts were studied using (C57BL/6J x A/J)F1 mice as recipients and DBA/2 mice as donors. In this strain combination, protracted rejection was noted in that the circulation was maintained in the graft for over 10 weeks. In all grafts examined after 3 weeks, mononuclear cell infiltrates were noted; in addition, all grafts had immune deposits, apparently containing transplantation antibodies, in glomeruli, tubuli and vessels. These results stressed the role of humoral immunity in protracted renal allograft rejection.

Interaction of antibodies with human glomerular epithelial cells.

We tested the hypothesis that the pathogenesis of human idiopathic membranous glomerulonephritis is similar to that of Heymann glomerulonephritis, a model of membranous glomerulonephritis induced in rats by immunization with renal brush border preparations; the characteristic subepithelial deposits result from interaction of antibodies with a brush border antigen (gp330) expressed on the plasma membrane of glomerular visceral epithelial cells (GEC), followed by redistribution and shedding of gp330 immune complexes. The experiments were performed in cultured glomerular visceral epithelial cells, in living monkeys and rats, and in isolated perfused human, monkey, and rat kidneys. Antigens from plasma membranes of human renal brush border vesicles (HBBV) and GEC vesicles (HGECV) and their corresponding polyclonal and monoclonal antibodies reactive with human and monkey GEC were prepared. First, polyclonal antibodies to HGECV bound diffusely to cultured GEC; monoclonal antibody 8G5, recognizing a 60-kDa protein, mainly bound to the coated pits and apical invaginations; both polyclonal HGECV and 8G5 monoclonal antibodies induced antigen redistribution (capping) at 37 degrees C. Second, monkeys were actively or passively immunized, and isolated human and monkey kidneys were perfused with the antibodies. Active immunization with HBBV induced tubular immune deposits, whereas active immunization with HGECV did not provoke renal lesions. After passive immunization HBBV and HGECV antibodies bound diffusely to glomerular cells, and subepithelial deposits were observed during the autologous phase; in contrast, 8G5 induced early (day 3) granular deposits. Third, fine granular deposits developed in glomeruli of human and monkey kidneys perfused for 4 hours at 37 degrees C with 8G5; these deposits were more difficult to detect by electron microscopy than those occurring in kidneys of Lewis rats perfused with sheep antiHBBV. The results show that some antibodies redistribute antigens at the surface of human and monkey GEC in vitro, in vivo, and ex vivo and induce formation of granular deposits in human glomerular capillary walls. Failure to induce more severe lesions in human and monkey kidneys may be ascribed to lack of GEC antigens comparable to rat gp330, insufficient cross linking by monoclonal antibody, lack or insufficient concentration of epitope-specific antibodies, insufficient time of kidney perfusion, or a combination of these factors.

Local formation of immune deposits in rabbit renal proximal tubules.

Rabbits passively immunized with goat antibodies to rabbit angiotensin converting enzyme (ACE), an enzyme synthesized in the endoplasmic reticulum and mainly expressed on the apical membranes of the cells of proximal tubules, developed mild and transient immune deposits in this segment of the nephron. Granular deposits of goat IgG, rabbit ACE and C3 were found in the basolateral compartment and were maximal during the first week of immunization when the highest titers of anti-ACE antibodies were present. As the antibody titer fell to an undetectable level, the immune deposits were rapidly cleared and were virtually absent 21 days after the injections. Artificial increase of glomerular permeability allowed focal binding of ACE antibodies to the brush border of some tubules, but did not significantly alter the pattern of immune injury at the base of tubular cells. The data are consistent with the interpretation that the immune deposits result from in situ formation of immune complexes. This mechanism would involve passage of circulating antibodies across the tubular basement membrane and their combination with ACE associated with tubular cell surface membranes.

Effect of chlorpromazine on the development of experimental glomerulonephritis and Arthus reaction.

Chlorpromazine blocks antibody-mediated redistribution of cell surface antigens in vitro and in vivo and inhibits the development of passive Heymann glomerulonephritis, a disease characterized by in situ formation of immune complexes (Camussi et al J Immunol 1986, 136:2127-2135). The aim of this study was to establish whether chlorpromazine exerts similar effects in other rat models characterized by in situ formation of immune complexes. In glomerulonephritis induced by antibodies reactive with an exogenous antigen "planted" in glomeruli pretreatment with chlorpromazine prevented formation of "humps" and exudative and proliferative lesions. Likewise, chlorpromazine prevented passive reverse Arthus reaction in the skin. In contrast, the drug was ineffective when these lesions were already established, and also failed to inhibit the fulminant course of nephrotoxic serum glomerulonephritis with an enhanced autologous phase. It is proposed that the antiinflammatory effect of chlorpromazine is due to its ability to block the recruitment of inflammatory cells and the release of inflammatory mediators.

Release of platelet-activating factor from rabbit heart perfused in vitro by sera with transplantation alloantibodies.

During "hyperacute rejection" of rabbit heart perfused with transplantation alloantibodies, platelet activating factor (PAF) was released into the coronary effluent, which appeared to have physicochemical and functional properties similar to the 1-octadecyl-2-acetyl-sn-glyceryl-3-phosphorylcholine (synthetic PAF) and to PAF obtained from IgE-sensitized rabbit basophils. The release of PAF was associated with an early tachycardia, followed by increasing bradycardia and conduction arrhythmias, as well as decrease of coronary flow and of amplitude of electrogram. The heart stopped beating within 30 min. The release of PAF as well as the "rejection" required the presence of fresh rabbit serum as a source of complement. The PAF receptor antagonist SRI 63-072 in a dose of 0.6 mg, reversed by 70% the reduction of coronary flow within 2-4 min after its addition to the perfusate; ED50 was 0.4 mg. Bradycardia and arrhythmia were reduced; however, the normal electrical activity was only occasionally restored. The cessation of heart action was delayed up to 50 min after the beginning of perfusion with transplantation alloantibodies and complement, but it was not prevented. These results suggest that PAF is released during "rejection" of the heart perfused in vitro with serum containing transplantation alloantibodies in the absence of inflammatory cells and that this mediator is at least in part responsible for the deterioration of cardiac function.