Case report: acyclovir neurotoxicity and nephrotoxicity--the role for hemodialysis.

Severe neurotoxicity and acute renal failure developed in a patient with newly diagnosed AIDS while receiving high-dosage intravenous acyclovir for disseminated herpes zoster. Hemodialysis resulted in a rapid resolution of neurologic symptoms and was associated with a reduction in plasma acyclovir concentration. Acute hemodialysis therapy should be considered in cases of serious neurotoxicity secondary to acyclovir, especially when accompanied by renal failure.

Inhibition of calcium oxalate crystal growth in vitro by uropontin: another member of the aspartic acid-rich protein superfamily.

The majority of human urinary stones are primarily composed of calcium salts. Although normal urine is frequently supersaturated with respect to calcium oxalate, most humans do not form stones. Inhibitors are among the multiple factors that may influence the complex process of urinary stone formation. We have isolated an inhibitor of calcium oxalate crystal growth from human urine by monoclonal antibody immunoaffinity chromatography. The N-terminal amino acid sequence and acidic amino acid content of this aspartic acid-rich protein, uropontin, are similar to those of other pontin proteins from bone, plasma, breast milk, and cells. The inhibitory effect of uropontin on calcium oxalate crystal growth in vitro supports the concept that pontins may have a regulatory role. This function would be analogous to that of other members of the aspartic acid-rich protein superfamily, which stereospecifically regulate the mineralization fronts of calcium-containing crystals.

Antithrombotic agents from salivary glands of hematophagous animals.

The introduction of thrombolytic agents and adjunctive anticoagulant therapy in acute myocardial infarction and heparin-aspirin combinations in unstable angina have resulted in major gains in the acute management of these disorders; however, it is widely believed that available therapeutic agents, such as streptokinase and tissue plasminogen activator (t-PA), anticoagulants, such as heparin, and antiplatelet agents, such as aspirin, may not possess the optimal efficacy and safety profile. A major surge was initiated to identify alternative thrombolytic and antithrombotic drugs, and as a part of these efforts the isolation and characterization of protein salivary anticoagulants from hematophagous animal species has assumed importance. In the following, we briefly review these proteins and the development of peptides and peptidomimetic compounds based on their structures and discuss the potential utility of these compounds in cardiovascular disease therapy.

Molecular characterization of a major nephritogenic domain in the autoantigen of anti-tubular basement membrane disease.

Anti-tubular basement membrane (alpha TBM) disease is a form of primary interstitial nephritis mediated by autoimmune T cells and alpha TBM antibodies. In mice and humans the nephritogenic immune response is directed to a glycoprotein (3M-1) found along the proximal tubule of the kidney. We have isolated cDNAs from an expression library that encodes for the common framework domain of the 3M-1 antigen. This common domain was once related evolutionarily to a family of intermediate filament-associated proteins. Northern hybridization revealed that all isoforms of 3M-1 range between 1700 and 1900 base pairs and in situ hybridization studies indicate that transcripts are found in tubular epithelium. Candidate peptide fragments were deduced and synthesized from the sequence encoding this common framework domain, and one of the peptide residues was able to bind a monoclonal 3M-1-reactive alpha TBM antibody, stimulate the growth of 3M-1-reactive helper T cells, and induce nephritogenic effector T cells capable of producing interstitial nephritis. Our results indicate that a unique, immunodominant region of the 3M-1 antigen is an informative participant in the emergence of autoimmune injury to certain basement membranes.

After coronary thrombolysis and reperfusion, what next?

Thrombolytic therapy for the removal of intravascular thrombi was introduced when streptokinase was first given to humans 40 years ago, the same year the American College of Cardiology was founded. Streptokinase was first administered to patients with acute myocardial infarction in 1959. Today, thrombolytic therapy has been established to offer significant benefits to patients with acute myocardial infarction provided they are brought to medical attention early enough after the onset of symptoms. The two major agents, streptokinase and recombinant tissue-type plasminogen activator (rt-PA), have been shown to result in reperfusion of infarct-related arteries, to salvage ischemic myocardium, to improve myocardial performance and to reduce mortality. In spite of these impressive gains, this novel therapy has shortcomings. The interval from the start of thrombolytic treatment to coronary reperfusion varies significantly from patient to patient and may, at times, be too long to produce a real benefit in terms of salvage of ischemic myocardium. The rate of reocclusion lies somewhere between 10% and 20% and appears not to be influenced by concomitant heparin anticoagulation. The rate of bleeding complications even with the "fibrin-specific" rt-PA is higher than anticipated and may range from 10% to 30%. As a consequence, intensive efforts are being directed at the development of improved thrombolytic agents and for adjunctive therapy evaluating better anticoagulants than heparin and better antiplatelet agents than aspirin. This review is a status report summarizing where we are in thrombolytic therapy in acute myocardial infarction, where we need to improve treatment results and what is being done mainly at the preclinical level to bring about such improvements.

Vancomycin allergy presenting as fever of unknown origin.

A 37-year-old woman receiving long-term hemodialysis was admitted to the hospital with a fever of unknown origin (6 weeks of unexplained, persistent, low-grade fever). Although she had received vancomycin hydrochloride 5 days before the onset of fever, the drug was not suspected as the cause because of the duration of fever, the administration of vancomycin on prior occasions without incident, and the lack of allergic stigmata. After hospitalization, vancomycin and gentamicin sulfate were administered empirically. Immediately thereafter, her temperature rose to 40 degrees C, and over the ensuing 24 hours, eosinophilia and a maculopapular rash developed that resolved entirely when antibiotic therapy was stopped and low-dose steroid therapy was instituted. The prolonged hypersensitivity reaction after a single dose of vancomycin is consistent with the greatly extended half-life of this drug in the population with end-stage renal disease and should alert physicians to the possibility of such persistent idiosyncratic reactions in this group.

Clonotypic heterogeneity in experimental interstitial nephritis. Restricted specificity of the anti-tubular basement membrane B cell repertoire is associated with a disease-modifying crossreactive idiotype.

Experimental anti-tubular basement membrane (anti-TBM) disease is an autoimmune interstitial nephritis elicited in susceptible rodents after immunization with renal tubular antigen. The nephritogenic antigen in the immunizing preparation is 3M-1, a 48,000 Mr noncollagenous glycoprotein. The hallmarks of the renal lesion are the presence of anti-TBM antibodies (anti-TBM-Ab) and a dense mononuclear cell infiltrate. The anti-TBM B cell repertoire in this disease was analyzed using a library of 22 anti-TBM mAbs generated in a prototypically susceptible Brown Norway rat. These anti-TBM mAbs were all demonstrated to be 3M-1 specific and their characterization formed the basis for the following observations: (a) The size of the anti-TBM B cell population is estimated at 58 distinct clones; (b) by competitive inhibition criteria, all anti-TBM mAbs recognize the same (or spatially close) epitope(s) on 3M-1. This focused recognition was maintained in spite of considerable variability in affinity. Epitopic dominance could also be demonstrated in human polyclonal anti-TBM antisera from a patient with anti-TBM disease; and (c) a crossreactive idiotype was documented, and antisera directed toward this set of variable region determinants was shown to be effective as a prophylactic regimen to abrogate disease, and as a therapeutic modality to arrest the progression of disease; (d) analysis of VH gene families suggested biased usage of Q52- and 7183-like families, although at least three gene families are used in the anti-TBM-Ab response. Thus, the anti-TBM B cell compartment in BN rats is moderately large, but is primarily focused to a single epitope on the nephritogenic antigen and is associated with a disease-modifying crossreactive idiotype.

Elution of kidney-bound antibody by pH-shift does not discriminate between antibodies differing in functional affinity for their ligand.

Antibodies eluted from kidneys by traditional methods of pH shift have been used as reagents in a wide variety of experimental analyses without knowledge of whether their ligand affinity influenced their removal from parenchymal tissue. In the current study we employed two monoclonal antibodies, differing only in their functional affinity (high; K = 2.1 x 10(8)/M and low; K = 6.2 x 10(6)/M) to a common ligand found on the renal basement membrane, to evaluate whether a standard elution technique might selectively facilitate the removal of one antibody over the other. Our findings indicate, however, that the routine methods of elution by pH shift remove both antibodies equally well (41-48%), and without loss of paratypic function. These results provide new evidence that elution by pH shift can produce eluate antibodies which are not biased by preferred affinities.

Murine interstitial nephritis. VI. Characterization of the B cell response in anti-tubular basement membrane disease.

In the present study we have examined the murine B cell response in anti-tubular basement membrane (alpha TBM) disease. Whereas only certain strains of mice are susceptible to the development of interstitial lesions after immunization with heterologous renal tubular antigen, all strains make anti-tubular basement membrane antibodies (alpha TBM-Ab), and all express the 3M-1 kidney antigen which is the target of disease. The magnitude of the alpha TBM-Ab response in serum and renal eluates, measured by radioimmunoassay against crude tubular antigen or affinity-purified 3M-1, also mapped independently of susceptibility. The fine specificity of epitope binding was further analyzed using a rat monoclonal alpha 3M-1 antibody to competitively inhibit the binding of renal eluate antibody to 3M-1. Maximum inhibition among nearly all tested strains ranged from 46 to 56% with no discernible difference between susceptible and nonsusceptible mice. Idiotypic representation of renal eluate alpha TBM-Ab was then evaluated by competitive inhibition using a polymorphic anti-idiotypic antisera. All mice examined possessed almost identical competitive inhibition patterns, indicating surprisingly similar idiotypic representation. Thus, in susceptible or nonsusceptible mice, neither the quantitative alpha TBM-Ab response, the epitopic fine specificity of that response, nor the idiotype of eluted alpha TBM-Ab serve as distinguishing markers for susceptibility to interstitial injury. Finally, passive transfer experiments with high-titered (greater than 1:10,000) alpha TBM-Ab from SJL mice were performed to test the hypothesis that alpha TBM-Ab alone may be sufficient for the induction of alpha TBM disease. Whereas this antiserum was capable of causing typical, severe alpha TBM disease in naive susceptible SJL mice, this treatment in allotype-identical, nonsusceptible B10.S(8R) mice was completely without effect. These data demonstrate, in conclusion, that, in the absence of appropriate susceptibility genes, alpha TBM-Ab are incapable of causing alpha TBM disease. The findings support previous observations that the ability of passively transferred alpha TBM-Ab to initiate interstitial injury is dependent on the host also expressing other susceptibility genes which promote the cooperative engagement of the cell-mediated immune response.

Murine interstitial nephritis. VII. Suppression of renal injury after treatment with soluble suppressor factor TsF1.

We prepared soluble suppressor T cell factor (TsF1) from donor spleens harvested from mice primed with tubular antigen-derivatized lymphocytes to analyze both its functional interactions with a larger suppressor T cell network and its influence on the nephritogenic effector T cell response producing interstitial nephritis to a parenchymal antigen. Our findings indicate that TsF1 is antigen-specific, genetically restricted by I-J in its direct mediation of suppression, and capable of inhibiting the development of interstitial lesions. TsF1 also provides an inducing signal for the activation of effector Ts-2 suppressors following presentation by accessory cells. The induction of a Ts-2 effect, however, requires that the factor-presenting cell and the recipient of such cells share homology at I-J, and that the TsF1, the precursor Ts-2 cells, and the recipient of the Ts-2 effect share the same Igh-V allotype. Finally, the results of this current report clearly demonstrate a possible therapeutic role for soluble suppressor factors in the management of interstitial renal disease.

Effector T cell differentiation in experimental interstitial nephritis. I. The development and modulation of effector lymphocyte maturation by I-J+ regulatory T cells.

Because mice susceptible to interstitial nephritis use different effector T cells than nonsusceptible mice, we analyzed the differentiation process of the effector T cell repertoire by using an in vitro culture technique. In the presence of helper T lymphocytes, accessory cells, IL 2, tubular antigen, and precursor effector cells, both Lyt-2+ nephritogenic effector cells and L3T4+ nonnephritogenic effector cells can be initially induced in both susceptible and nonsusceptible strains within 3 days of culture. In nonsusceptible mice, however, the Lyt-2+ nephritogenic cell is inhibited from further development and disappears, whereas in susceptible mice, its presence is preserved with a resulting effect of tissue destruction. This selection of effector T cell preference is regulated by I-J+ T lymphocytes which are co-functionally expressed with effector cell expansion. Unlike precursor effector lymphocytes, however, the maturation of the regulatory process requires a subset of I-J+ accessory cells and structurally intact tubular antigen. Our findings indicate, therefore, that both susceptible and nonsusceptible mice have the potential for the expression of interstitial nephritis, but nonsusceptible mice are formally protected from autoimmunity by the regulation of lymphocyte preference.

The Limulus amebocyte lysate assay. A rapid and sensitive method for diagnosing early gram-negative peritonitis in patients undergoing continuous ambulatory peritoneal dialysis.

The Limulus amebocyte lysate (LAL) assay was used in a blinded, prospective fashion to analyze peritoneal fluids from 35 consecutive patients undergoing continuous ambulatory peritoneal dialysis (CAPD), who presented with clinical peritonitis. The results were correlated with standard microbiologic culture results. The LAL assay was positive in all three patients with gram-negative peritonitis, was appropriately negative in 24 of 28 gram-positive infections (sensitivity, 100%; specificity, 86%) and was positive in two of five cases in which there was no microbiologic growth. One of the two patients in this last group yielded a gram-negative organism two days later. It was then demonstrated that therapeutic concentrations of a variety of antibiotics (cefazolin sodium, gentamicin sulfate, tobramycin sulfate, ticarcillin disodium, penicillin G potassium, vancomycin hydrochloride, metronidazole hydrochloride, piperacillin sodium, and trimethoprim/sulfamethoxazole) did not interfere with the LAL assay. Together, these data indicate that the LAL assay is useful for identifying patients at high risk for gram-negative peritonitis and for excluding from possible aminoglycoside exposure the majority of patients with peritonitis undergoing CAPD, most of whom will have gram-positive infections. Furthermore, lack of antibiotic interference allows the possibility of monitoring treatment efficacy.

Therapeutic immune regulation in experimental interstitial nephritis with suppressor T cells and their soluble factors.

The therapeutic application of immune regulation and suppressor T cells to the control and modulation of autoimmune disease is an area of growing experimental interest. Our group has been studying experimental interstitial nephritis, both to better understand the disease process itself and to test immunoregulatory strategies for their inhibitory and protective effects. This report gives a brief overview of this work.

Experimental strategies for the study of cellular immunity in renal disease.

This overview has examined some of the current experimental options available for the study of cellular immunity in the immunopathogenesis of renal disease. T cell immunity, where it has been examined, seems to have a particularly pivotal role in orchestrating and regulating functional patterns of renal injury. The use of the research methods presented here for the study of cell-mediated interactional events in kidney disease, however, has lagged behind similar efforts in other organ systems. We hope, therefore, this report will serve to stimulate and strengthen further interest in the cell biology of the nephritogenic immune response.

Isolation of the target antigen of human anti-tubular basement membrane antibody-associated interstitial nephritis.

Using a monoclonal anti-tubular basement membrane antibody (alpha TBM-Ab) affinity column, we isolated from collagenase-solubilized human renal tissue (HSRTA) a predominantly 48,000-mol-wt moiety (H3M-1) which is selectively recognized by antisera from two patients with alpha TBM-Ab-associated interstitial nephritis (alpha TBM disease). Whereas both antisera had alpha TBM-Ab titers of 1:64-1:128 by immunofluorescence on tissue sections, their reactivity with H3M-1 in a solid-phase radioimmunoassay was demonstrable at dilutions up to 1:10,000. While these sera displayed some reactivity with pre-column HSRTA, this was markedly less than with H3M-1. HSRTA depleted of H3M-1 by passage over the alpha TBM-Ab affinity column was almost completely depleted of reactivity. Neither pooled normal human sera nor sera from patients with a variety of renal lesions not associated with alpha TBM-Ab (including interstitial nephritis and antiglomerular basement membrane disease) were reactive with H3M-1. Both patient antisera containing alpha TBM-Ab were also highly reactive with R3M-1, the 48,000-mol-wt rabbit glycoprotein antigen of experimental alpha TBM disease. Furthermore, a competitive inhibition radioimmunoassay revealed that alpha TBM-Ab from rodents with experimental alpha TBM disease could inhibit 45-98% of the R3M-1 binding reactivity of patient antisera and 85% of the H3M-1 binding reactivity of patient antisera, thus suggesting paratypic cross-reactivity. We conclude, therefore, that tubular basement membrane target epitopes and their paratypic recognition are highly conserved among mammals.

Immunoregulation in experimental interstitial nephritis: immunization with renal tubular antigen in incomplete Freund's adjuvant induces major histocompatibility complex-restricted, OX8+ suppressor T cells which are antigen-specific and inhibit the expression of disease.

We utilized a model of experimental interstitial nephritis induced by renal tubular antigen in complete Freund's adjuvant to examine a mechanism of immunologic tolerance produced by priming immunization with tubular antigen in incomplete Freund's adjuvant. Brown Norway rats primed with tubular antigen in incomplete adjuvant do not develop significant nephritis after challenge with antigen in complete adjuvant, and this tolerance can be transferred to naive recipients with donor T cells. These T cells also specifically suppress a delayed-type hypersensitivity response to soluble tubular antigen in recipients immunized to produce disease. This suppression is MHC-restricted and is mediated by OX8+ T cells which bind antigen and bear idiotypes cross-reactive with those on antibodies eluted from the tubular basement membrane. Despite the suppression of histologic disease, tolerized animals were able to produce significant titers of antibodies to tubular basement membrane. Our findings demonstrate an additional strategy for altering the natural history of immune-mediated renal disease, and further refine the characterization of the suppressive effect produced by incomplete Freund's adjuvant.

Isolation and characterization of the nephritogenic antigen producing anti-tubular basement membrane disease.

Using monoclonal antibody affinity chromatography, we isolated a 48,000 mol wt, glucose-rich glycoprotein (3M-1) from collagenase-solubilized rabbit renal tubular basement membrane (SRTA). The purified 3M-1 protein is noncollagenous, and is capable of inducing anti-TBM (tubular basement membrane) antibodies and interstitial nephritis in susceptible hosts. Further, when SRTA, at a normally nephritogenic dose, was selectively depleted of 3M-1, it lost its ability to induce disease. As shown by immunofluorescent techniques, 3M-1 appears to be localized on rodent TBM to the exclusion of the glomerular basement membrane, but was lacking in the TBM of the LEW rat, a strain devoid of the relevant antigen of anti-TBM disease. Immunoelectron microscopy revealed that 3M-1 was associated with the most lateral aspect of the TBM, which borders, and lies in the interstitium. These results indicate that 3M-1 is the nephritogenic antigen producing experimental anti-TBM disease.

Spontaneous interstitial nephritis in kdkd mice. I. An experimental model of autoimmune renal disease.

Mice of the kdkd strain predictably develop a spontaneous tubulointerstitial nephritis after 8 wk of life. In this report we have examined several aspects of the nephritogenic immune response that seemed potentially relevant to the expression of this progressively destructive renal lesion. Of particular interest is that by direct immunofluorescence we were unable to demonstrate the presence of antibodies to determinants in the tubulointerstitium. Serum and kidney eluates from nephritic mice, furthermore, did not stain any renal structures in normal kidney. We did observe, however, that disease could be transferred through kdkd----CBA/Ca bone marrow chimeras, and prevented, in the reverse direction, by CBA/Ca----kdkd chimeras. The development of the interstitial lesion was markedly inhibited by thymectomy with T cell depletion, but disease could not be adoptively transferred with cells or serum from nephritic mice. The interstitial lesions also did not appear in (kdkd X CBA/Ca)F1 hybrids, and the development of disease in kdkd mice could be inhibited by treatment with adoptively transferred T cells from CBA/Ca mice. With these new findings we now hypothesize that susceptibility to the expression of interstitial nephritis in kdkd mice involves the cellular limb of the immune system, and may be related, in part, to alterations in regulatory T cell function.

Antiidiotypic immunity in interstitial nephritis. II. Rats developing anti-tubular basement membrane disease fail to make an antiidiotypic regulatory response: the modulatory role of an RT7.1+, OX8- suppressor T cell mechanism.

Antiidiotypic immunity can successfully inhibit the development of antitubular basement membrane (alpha TBM) disease that produces interstitial nephritis. Rats normally immunized to produce disease, however, do not develop this regulatory and protective antiidiotypic effect. The failure to see such a regulatory response is functionally related to the influence of a nonspecific, RT7.1+, OX8-suppressor T cell that appears shortly after immunization. While this suppressor cell system can partially reduce the intensity of disease, it also limits the host's ability to specifically regulate the alpha TBM immune response and, hypothetically, leaves the disease process in an operationally active mode.