New Zealand mixed mice: a genetic systemic lupus erythematosus model for assessing environmental effects

Systemic lupus erythematosus (SLE) is a multiphenotypic autoimmune disease. The hallmark of SLE is the production of anti-double-stranded DNA autoantibodies and the deposition of immune complexes in target tissues such as the kidney, skin, and brain. Additional phenotypic traits are the presence of arthritis, anemia, central nervous system involvement, and a variety of autoantibodies. Females of childbearing age are particularly at risk. Recent genetic analysis of murine SLE shows that susceptibility is under complex polygenic control. It is also apparent that environmental factors contribute to the induction and exacerbation of SLE. We describe here the genotypic and phenotypic characterization of a group of recombinant inbred strains of SLE-prone mice that were derived from NZB and NZW progenitors, the parental strains of the classic female F1 hybrid lupus model. Recombination and reassortment of these ancestral genomes resulted in the NZM (New Zealand mixed) strains with strain-specific patterns of renal disease penetrance and other autoimmune traits such as Coombs positive anemia and neurologic deficits. Multiple susceptibility loci of the ancestral strains demonstrate that SLE is inherited as a threshold trait. Because some of these loci co-localize with the susceptibility loci of the insulin-dependent diabetes of nonobese diabetic strain, it is apparent that there are disease-specific as well as autoimmunity-promoting genes. It is proposed that the NZM strains, particularly those with reduced disease penetrance or partial genotypes, provide an improved genetic model for assessment of the effects of environmental agents on SLE and autoimmunity.

Multiplex inheritance of component phenotypes in a murine model of lupus

We analyzed the linkage of GN and a wide spectrum of serological phenotypes associated with systemic lupus erythematosus in a (NZM2410 x C57BL/6)F2 cross. Some phenotypes, such as glomerulonephritis (GN) and anti-chromatin IgG antibody production, were more penetrant in females, but others, such as anti-dsDNA antibody production, did not show a gender bias. These results suggest that gender bias affects only a subset of SLE-component phenotypes, and that NZM2410 can be used to dissect the genetic basis of this phenomenon. Genome scanning linked six chromosomal intervals with the expression of one or more component phenotypes. These loci included two Sle loci previously identified in an (NZM2410 x B6)F1 x NZM2410 backcross, loci identified by others in the NZB/W model. Our analysis also suggested two new intervals on chromosomes (Chrs.) 10 and 11. Detailed analysis of the segregation of different phenotypes within these intervals suggests that they encompass more than one susceptibility locus. This clustering has been a common finding in several murine polygenic traits. Each of NZM2410 susceptibility loci can be aligned with a specific genetic pathways contributing to SLE pathogenesis on the basis of the spectrum of component phenotypes expressed.

Purification, microsequencing, and immunolocalization of p36, a new interferon-alpha-induced protein that is associated with human lupus inclusions

The trace interferon-alpha-induced protein, p36, was induced in Raji cells in association with lupus inclusions. It was solubilized in a nonionic detergent buffer, enriched by differential centrifugation and by preparative isoelectric focusing, and purified to homogeneity on two-dimensional protein gels. Failure to obtain N-terminal amino acid sequence, however, suggested a blocked alpha-amino group. Sequences of six tryptic peptides, 13-19 amino acids in length, were obtained after digestion, microbore-high performance liquid chromotography purification, and chemical sequence analysis. None of the six sequences, which represented approximately 25% of the entire protein, shared any meaningful homologies with entries in protein sequence repositories. Raji-cell p36 was shown in Western blots with antipeptide antibodies to be induced at least 400-fold and by immunofluorescence microscopy to co-localize with the endoplasmic reticulum resident protein, protein disulfide isomerase. These results show that p36 is a new interferon-alpha-induced protein that localizes in the endoplasmic reticulum, the cell region in which the lupus inclusions form, and that p36 is probably physically associated with the lupus inclusions.

Defective antigen-receptor-mediated regulation of immunoglobulin production in B cells from autoimmune strains of mice

B cells are stimulated by antigens or by polyclonal activators such as bacterial lipopolysaccharide (LPS) to produce antibody. In nonautoimmune strains of mice, LPS-stimulated antibody responses are inhibited by crosslinking the B cell antigen-receptor (BCR), while antigen-driven responses are shut down by co-crosslinking the BCR and the receptor for the Fc portion of IgG (Fc gamma R). BCR signals are poor at shutting off LPS-induced antibody production, including anti-ssDNA antibody production, in B cells from NZB, NZB/WF1, and BXSB lupus-prone mice but not MRL/lpr or NZW mice. In the current studies, the defect in NZB B cells was shown to be independent of T cells and macrophages. The inheritance pattern of resistance to BCR ligation of LPS-induced Ig production in BXSB mice could not be assigned to either founding strain. In New Zealand mixed (NZM) recombinant inbred mice, slightly but significantly more resistance was found in a line (NZM2410) that demonstrates a greater degree of clinical autoimmunity than another line (NZM64) with fewer autoimmune problems. The autoimmune defect is specific to BCR signals because inhibition of LPS activation by ligation of MHC class II occurs normally in NZB B cells. Bypassing the BCR by direct stimulation of second messengers with phorbol esters or ionomycin did not overcome the defect, suggesting that defects in downstream signaling events, rather than in the BCR mechanism itself, are responsible for the reduced ability to inhibit the LPS response in NZB B cells. The inability of the BCR signaling pathway to control LPS-induced Ig production in NZB mice was apparent at the level of H mu-chain mRNA for secreted IgM. These results suggest that autoimmunity-associated B cell defects in BCR signaling and subsequent regulation of LPS-driven antibody responses have a number of inheritance patterns and involve downstream events in signaling pathways in B cells. The defect can result in aberrant regulation of H mu-chain mRNA levels for secreted IgM production, and may be a predisposing factor in murine systemic autoimmune disease.

Polygenic control of susceptibility to murine systemic lupus erythematosus

Susceptibility to glomerulonephritis (GN) and anti-dsDNA autoantibody production was analyzed in crosses with a newly developed systemic lupus erythematosus-susceptible inbred strain, NZM/Aeg2410. The mode of inheritance and the number and location of systemic lupus erythematosus-associated susceptibility loci were analyzed by interval mapping in a backcross with C57BL/6. Three chromosomal intervals containing strong recessive GN susceptibility alleles were identified on chromosomes 1, 4, and 7, each containing several potentially interesting candidate genes. Heterozygosity at H-2 was also found to correlate strongly with GN susceptibility, consistent with previous findings in the NZB/NZW parental strain model. Logistic regression analysis indicated that each of these susceptibility alleles independently accounted for a component of GN susceptibility, and that susceptibility was inherited as a threshold genetic liability in this model system.

Subcellular distribution of adenosine deaminase and adenosine deaminase-complexing protein in rabbit kidney: implications for adenosine metabolism

We evaluated the age-related distribution of adenosine deaminase (ADA) and adenosine deaminase-complexing protein (CP) in rabbit kidney by immunohistochemical staining procedures. Paraffin- or resin-embedded tissue from rabbits < 1 week-4 years of age were stained by the peroxidase-anti-peroxidase (PAP) method for ADA and CP. With the exception of neonates, the qualitative staining pattern of each protein remained generally constant with age. In the cortex, distal tubules, blood vessels, histiocytes, and epithelial cells lining Bowman's capsule stained for ADA. Proximal tubules and glomeruli were positive for CP. In contrast to the segregated pattern in the cortex, staining for ADA and CP overlapped in the corticomedullary junction. ADA and CP co-localized on the brush border of tubule cells of the S3 segment. In the cytoplasm of these cells, staining for ADA was characterized by scattered punctuate deposits of peroxidase reaction product. In some instances these punctuate deposits also appeared to be positive for CP. In medulla, epithelial cells of the thin limb were positive for both ADA and CP, whereas papillary collecting ducts stained only for CP. These results document the age-related, tissue-specific expression and localization of ADA in renal tissue, features that probably reflect the crucial role played by the enzyme in adenosine/deoxyadenosine catabolism. In addition, colocalization of ADA and CP on the brush border of cells in the S3 segment of proximal tubules provides support for the hypothesis that one function of CP may be to position ADA on the plasma membrane of specific cell populations, further expanding the enzyme's utility in nucleoside metabolism.

Monoclonal antibody to native P39 protein from Borrelia burgdorferi

We have produced, by using a sonicate of Borrelia burgdorferi, a monoclonal antibody (MAb), NYSP39H, that is specific for the P39 protein band. This MAb reacted with 13 isolates of B. burgdorferi but not with eight different spirochetes (four borrelias, two leptospiras, and two treponemas). Surface labeling of B. burgdorferi with biotin and subsequent treatment with Nonidet P-40 showed that P39 was not biotinylated but was extracted with Nonidet P-40, indicating that it is present within the outer membrane, but not on the surface of the spirochete. Immunoelectron microscopy revealed the immunogold probe primarily at the cytoplasmic membrane region of the spirochete. The MAb detected B. burgdorferi in the indirect fluorescent-antibody test only when the spirochetes from a culture or in a tick homogenate were fixed with polylysine and not with acetone. NYSP39H appears to be an appropriate probe for use in the specific detection of B. burgdorferi.

Differences in expression of lupus nephritis in New Zealand mixed H-2z homozygous inbred strains of mice derived from New Zealand black and New Zealand white mice. Origins and initial characterization

BACKGROUND

F1 hybrids of New Zealand Black (NZB) and New Zealand White (NZW) mice develop autoimmune glomerulonephritis resembling human lupus nephritis. Susceptibility to this complex autoimmune syndrome in humans and mice has been linked to genes mapping in or near the major histocompatibility complex that govern immune responses and levels of certain complement components. Previous studies showed that both parental strains contribute major histocompatibility complex-linked genes that are important for disease of the F1 hybrid.

EXPERIMENTAL DESIGN

New inbred strains of New Zealand Mixed (NZM) mice were derived by selective inbreeding of progeny of a cross between NZB and NZW mice. Twelve of the 27 new NZM strains were selected for analysis. Mice were observed for up to 10 months of age to document the occurrence of nephritis and strain-specific differences in disease expression. H-2, Hc, and coat color loci were determined for each strain to establish homozygosity of NZB and NZW polymorphic markers. Strains were screened for the presence of anti-dsDNA autoantibodies.

RESULTS

In some NZM strains early onset of lupus nephritis in females resembled the (NZB x NZW)F1 model, whereas in other strains early disease also occurred in males. Age at death and severity of nephritis vary among the lines; a few strains remain relatively free of glomerular lesions. Histocompatibility (H-2) typing showed that all strains are homozygous for the NZW haplotype (Ku, Au, Sz, Dz). Coat color analysis for four loci on chromosomes 2, 4, and 7 was consistent with specific reassortments and recombinations to explain the grey, tan, and white mice with red/pink eyes and the presence or absence of the fifth component of serum complement (C5) (Hc, chromosome 2). Anti-dsDNA autoantibodies were found in all but one of the NZM strains reported here.

CONCLUSIONS

The NZM strains of mice are a unique set of inbred strains that have inherited various genomic segments of the two parental strains that lead to phenotypic differences in disease expression. These results indicate that the previously proposed strict requirement for H-2 heterozygosity for the development of nephritis in the (NZB x NZW)F1 hybrid mice may not be valid. It is assumed that both the Lpn-1 locus of NZB and the Lpn-2 locus of NZW and a sufficient number of other disease-associated genes of both ancestral strains have been recombined in these new strains to produce the various patterns of renal disease.

Modulation of urinary kallikrein and plasma renin activities does not affect established hypertension in the fawn-hooded rat

Fawn-hooded (FH) rats develop low-renin hypertension which is preceded by a decrease in urinary kallikrein. We examined urinary excretion of active and inactive kallikrein in hypertensive FH male rats and matched animals of the ancestral, normotensive Wistar strain. To determine the effects of modulation of salt intake on the kallikrein profile, rats were given standard rat chow (0.39% NaCl), a low-salt diet (0.02% NaCl), or a high-salt diet (standard chow plus water with 1% NaCl). Control FH rats excreted less active kallikrein (p less than 0.02), had similar amounts of inactive kallikrein, and had a higher inactive/active kallikrein ratio (p less than 0.02) than control Wistar rats. Low salt intake increased active kallikrein 136% (p less than 0.002) and 54% (p less than 0.035) in FH and Wistar rats, respectively, but did not change the level of inactive kallikrein or the inactive/active kallikrein ratio. High salt intake had no effect on kallikrein excretion in either strain. Low salt intake did not change blood pressure in either strain in spite of significant changes in plasma renin activity, angiotensin II and active kallikrein excretion. The low urinary active kallikrein and the high inactive/active kallikrein ratio in FH rats do not appear to play a role in the established hypertension in the FH rat, since modulation of these parameters did not cause a significant change in the elevated blood pressure.

Elevation of plasma fibronectin and serum amyloid P in autoimmune NZB, B/W, and MRL/1pr mice

The acute-phase proteins, fibronectin (Fn) and serum amyloid P (SAP), are opsonins which by virtue of their adhesive properties may be involved in the glomerular nephritis associated with splenic lupus erythematosus (SLE). Because of their possible involvement in the pathophysiology of lupus, plasma Fn and SAP levels from three strains of autoimmune mice were measured over time to determine if Fn and SAP rose as the mice sickened and renal function degenerated. Baseline levels of Fn and SAP were measured when the mice were between 1.5 and 3 months of age. The characteristic rapid onset of autoimmune disease in MRL/1pr mice was accompanied by a two- to threefold increase in plasma Fn and SAP by Day 100. The B/W mice, which develop autoimmune disease more slowly, did not have a significant increase in plasma Fn and SAP until Day 240. The NZB mice, with the most delayed onset of disease, exhibited a modest but significant elevation of plasma Fn and SAP by Day 360. Histologic examination of the kidneys of B/W and NZB mice indicated that pathological abnormality of the glomeruli and tubules coincided with the elevation of plasma Fn and SAP levels. In contrast, blood samples taken over time from normal BALB/c mice did not possess abnormal levels of Fn or SAP. It appears that elevation of plasma Fn and SAP in the MRL/1 pr, B/W, and NZB mice is related to the onset and severity of autoimmune disease and the subsequent loss of renal function.

Characterisation of IgE-mediated histamine release from equine basophils in vitro

In vitro IgE-mediated histamine release by equine blood basophils was characterised as the basis for a screening test for immediate hypersensitivity responses in horses. The responses are initiated by inducing agents that are capable of crosslinking or bridging the membrane-bound IgE molecules. The release process is complete within 40 mins. In vitro histamine release is dose-dependent, with a submaximal response at less or greater than the optimal dose of inducing agent. Exogenous calcium is required but not magnesium; the optimal release calcium concentration is 1.0 to 1.5 mM. If an IgE-mediated inducing agent is added in the absence of exogenous calcium, the basophils become desensitised. The pH and temperature optima for release are physiological (pH 7.4, 37 degrees C). Histamine release is potentiated by deuterium oxide.

Lack of passive transfer of renal tubulointerstitial disease by serum or monoclonal antibody specific for renal tubular antigens in the mouse

Mice immunized with rabbit renal basement membranes form autoantibodies to their kidney glomerular and tubular basement membranes (GBM/TBM). Development of renal tubular disease (RTD) consists of deposition of autoantibodies along the GBM/TBM with the inter- and intratubular accumulation of lymphocytes and macrophages and destruction of the TBM. Transfer of this disease in mice with either serum or monoclonal antibodies, however, has been difficult to demonstrate and, therefore, attempts were made to confirm a report that RTD is passively transferred by anti-TBM autoantibodies. Using the revised protocol in this later report, we found that 12 weeks after transfer autoantibodies were deposited along the GBM and/or TBM of the recipients, yet RTD was not observed. Although qualitative and quantitative characteristics of the antibody may play a role in the pathogenesis in the murine model of RTD, we could not obtain evidence to support and confirm this study.

HLA and survival in lung cancer

HLA A and B antigens were determined in a study of 125 patients with lung cancer. Differences between antigen frequencies in cancer and control populations were determined by chi 2 analysis or Fisher's exact test. Survival data were analyzed using the Cox model for censored data. Cancer patients had an increased frequency of the antigen Aw33 (relative risk = 10.5, P less than 0.016). The Cox model (D. R. Cox, J. R. Stat. Soc. B, 34, 187, 1972) indicated that four covariates had a significant effect on mean survival time independently: the presence of A3 (P less than 0.005) and of Aw33 (P less than 0.05) increased mean survival time of the cancer population; patients with anaplastic carcinoma and stage three of any histological type of cancer had a decreased mean survival time. The determination of HLA phenotypes, cancer type, and the stage of the disease can provide the expected mean survival time of any particular patient. This could be of importance for evaluating prognosis. The effect of Aw33 and A3 on survival time may be related to HLA closely linked genes, possibly coding for resistance to the disease.

Contrasting effects of early and late orchiectomy on hypertension and renal disease in fawn-hooded rats

Fawn-hooded (FH) rats, primarily males, develop spontaneous low-renin hypertension associated with reduced urinary excretion of kallikrein as early as 2 months of age, followed by progressive glomerular sclerosis and proteinuria as early as 3 months of age. In the present study we determined the effects of early (5-7 weeks) or late (5 months) orchiectomy on the blood pressure and nephropathy of FH rats, compared to sham-operated (control) FH males. Early orchiectomy reduced significantly the progression of glomerular sclerosis and of proteinuria and ameliorated the hypertension but had no significant effect on excretion of urinary kallikrein. Late orchiectomy, in contrast, had no significant effect on the progression of glomerular sclerosis or proteinuria but did significantly reduce the blood pressure and marginally increase the excretion of urine kallikrein. These results suggest that (a) male sex hormones may play a role in the pathogenesis of hypertension and nephropathy in the FH rats and (b) renal disease in this strain progresses in spite of improvement in blood pressure.

Increased catecholamine output in the hypertensive fawn-hooded rat

The total 24 hour urinary outputs of the catecholamines norepinephrine (NE), epinephrine (E), dopamine (DA) and the DA metabolite homovanillic acid (HVA) were measured in hypertensive fawn-hooded rats and compared to the ancestral strain of normotensive Wistar rats. The hypertensive fawn-hooded rats demonstrated significantly higher urinary outputs of the catecholamines NE and DA, and of the DA metabolite HVA. Following treatment with the antihypertensive, debrisoquin sulfate, the blood pressure of the fawn-hooded rats decreased until it approached the levels observed in normotensive Wistar rats. By inhibiting sympathetic nervous activity and monoamine oxidase, the debrisoquin treatment significantly decreased the output of DA, NE and HVA but not E. The data suggest the fawn-hooded rat is a model of neurogenic hypertension which is characterized by an increased sympathetic output.

Analysis of lead effects on in vivo antibody-mediated immunity in several mouse strains

The effect of administration of lead acetate (10 mM in the drinking water) for 8 weeks on the in vivo sheep red blood cell (SRBC) specific plaque-forming cell (PFC) responses of inbred A, BALB/c, C57Bl/6, DBA/1, SJL, and NZW/NZB F1 mice and outbred CFW mice was examined to determine if lead was immunomodulatory in a genetically related manner. Lead did not suppress the SRBC-specific PFC/10(6) splenocytes or PFC/spleen response in any mouse strain when compared to the responses of strain-matched control mice. In addition, 10 mM lead-treated BALB/c mice manifested augmented PFC/10(6) splenocytes (17%; p less than .05) but unchanged PFC/spleen responses. Correspondingly, serum concentrations of SRBC-specific antibody (measured by radioimmunoassay) and serum immunoglobulin G, M, or A isotypes were also unchanged by lead acetate treatment in all tested mouse strains. There were no observable lead-related histopathological changes or deposition of immune complexes or antibasement membrane antibody in the kidneys of treated mice. Further, splenocytes from lead-treated, SRBC-immunized mice cultured with T-independent antigens (TNP-LPS, TNP-Ficoll) or with a T-dependent antigen (SRBC) exhibited direct and indirect specific PFC responses that were unchanged from those of control mice. The H-2K/D haplotypes of the outbred CFW mice were determined by microcytotoxicity to include r, q, u, and s. These results suggest that lead acetate (10 mM) administered po for 8 weeks does not suppress the primary direct humoral immune response to SRBC in inbred and outbred mice of several H-2 haplotypes (k/d; d; b; q; d,z; s; r; and u).

Differences in the occurrence of hypertension among (NZB X NZW)F1, MRL-lpr, and BXSB mice with lupus nephritis

Lupus-prone (NZB X NZW)F1 (B X W) mice and MRL-lpr and BXSB mice were examined for the prevalence of hypertension and levels of plasma renin activity (PRA). Hypertension (greater than 145 mmHg) was observed only in female and male B X W mice with severe nephritis; in female MRL-lpr and male BXSB mice severe nephritis developed without blood pressure elevation (80-135 mmHg). The B X W parental strains, NZB and NZW, and the MRL-lpr congenic partners, MRL- +, did not become hypertensive as they aged. Other strains of mice, aged 3-32 months (A/HeN, BALB/cJ, BALB/cByJ, B10.S/Sg, B10.D2/ oSn , CBA/J, C3H/HeJ, SJL/J and [SJL X NZW]F1), also had normal blood pressure (98-122 mmHg). All mice with lupus nephritis had low PRA, even those with hypertension; furthermore, the MRL-lpr strain had low or undetectable PRA (2 +/- 1 ng/ml/hr), even when kidneys were normal. NZB, NZW, and MRL- + mice had normal PRA (10-16 ng/ml/hr). Thus, B X W mice frequently developed low renin hypertension during the last phase of their renal disease; whereas MRL-lpr and BXSB mice died from renal disease without observable increases in blood pressure.

Experimental autoimmune glomerulonephritis induced by anti-glomerular basement membrane antibody. II. Effects of injecting heterologous, homologous, or autologous glomerular basement membranes and complete Freund's adjuvant into sheep

The effects of injecting human, rabbit, rat, or single-kidney homologous glomerular basement membrane (GBM) or autologous GBM, each in complete Freund's adjuvant (CFA), into 15- to 18-month-old sheep are compared. All sheep receiving heterologous GBM and 3 of 6 sheep receiving homologous GBM had anti-GBM nephritis, but such sheep did not bind autoantibodies or have Goodpasturelike lesions in their lungs. Sheep given injections of human GBM had autoantibodies to antigenic determinants shared by fetal or adult sheep and human GBM, by lung basement membranes, and by certain nonvascular basement membranes. Sheep given homologous GBM had two populations of autoantibodies: one was neither species- nor organ-specific; the other was sheep-specific. No sheep given autologous GBM had any evidence of anti-GBM autoantibodies or nephritis. Their kidneys were indistinguishable by histologic, immunohistologic, and functional studies from CFA-treated controls. Thus, sheep seem very tolerant to autologous GBM. These findings suggest that human anti-GBM nephritis may occur if the GBM is altered so that it becomes cross-reacting and induces autoantibodies, as does homologous GBM.

Experimental autoimmune antiglomerular basement membrane antibody-induced glomerulonephritis. I. The effects of injecting sheep with human, homologous or autologous lung basement membranes and complete Freund's adjuvant

We compared the effects of injecting human, homologous or autologous lung basement membrane (LBM) and complete Freund's adjuvant into 6-month-old sheep and injecting the same antigens into guinea pigs. All sheep receiving human LBM died of antiglomerular basement membrane (GBM) nephritis by Day 126. They had autoantibodies to antigenic determinants shared by fetal or adult sheep and human LBM and GBM and certain nonvascular basement membranes, but these autoantibodies did not localize in the lung in vivo or cause lung hemorrhages. No sheep injected with homologous or autologous LBM had any evidence of anti-GBM autoantibodies or nephritis or specific lung lesions. Their kidneys are indistinguishable by histologic, immunohistologic, and functional studies from kidneys of age-matched controls. Thus, sheep are very tolerant to their own LBM. Although all guinea pigs developed anti-GBM autoantibodies, they did not get anti-GBM nephritis or specific lung lesions. A hypothesis for the pathogenesis of Goodpasture's syndrome is presented.

Effect of sulfhydryl-reactive ATPase inhibitors upon mast cell and basophil activation

Ethacrynic acid is an inhibitor of Ca2+-Mg2+-activated ATPases which also inhibits histamine release. By testing analogs of ethacrynic acid, the molecular structural requirements for ATPase inhibition and for inhibition of histamine release were compared. The results indicated that effective inhibition involves several structural features of the molecule. Analogs void of chlorine atoms were ineffective as inhibitors of histamine release and ATPase activity. Inhibition of both ATPase and histamine release requires a sulfhydryl-reactive olefinic bond, but sulfhydryl reactivity alone is not sufficient, as certain analogs which have a high capacity to react with sulfhydryl moieties were not active. Replacement of carboxy by highly ionized moieties like sulfo, rendered the molecules ineffective as an inhibitor of histamine release. Compounds which did not inhibit ATPase activity did not inhibit histamine release. The data indicate that mast cells and basophils require an intact ATPase system for histamine release, and raises the question of whether both ecto and endo ATPases are essential.

Spontaneous hypertension in fawn-hooded rats

By 2 to 3 months of age, many fawn-hooded rats, particularly males, had indirect systolic blood pressures of greater than 145 mm Hg; by 4 months of age, most males had persistent elevations in blood pressure (greater than 160 mm Hg). Female fawn-hooded rats developed hypertension at 4-5 months of age. Concurrently, fawn-hooded rats develop a severe form of focal glomerular sclerosis. The causes of the hypertension and focal glomerular sclerosis are yet not known, nor has a relation been found between these abnormalities.

Plasma renin activity decrease precedes spontaneous focal glomerular sclerosis in aging rats

An association between the activity of the renin-angiotensin system and the development of spontaneous focal glomerular sclerosis (FGS) in rats has been observed: the onset is preceded by a decrease in plasma renin activity (PRA). This observation was facilitated by the use of Fawn-hooded rats, which develop spontaneous FGS at an early age. Male Fawn-hooded rats develop severe FGS as early as 3 months of age. Male Wistar rats do not develop similar lesions until after 1 year of age. Correspondingly the PRA drops much sooner in Fawn-hooded than in Wistar rats. The low PRA appears to be due to low plasma renin rather than a limitation of the renin substrate, angiotensinogen, which appears to be present in the Fawn-hooded plasma in nonlimiting quantities. In the FH male rats renin content of the kidney drops only after severe glomerular pathology is evident, implying that the low PRA may be due to a decrease in renin secretion by the chromaffin cells of the juxtaglomerular apparatus.

Murine lupus nephritis is accelerated by anti-glomerular basement membrane autoantibodies

We have tested the effect of deposition of non-pathogenic amounts of induced anti-glomerular basement membrane (GBM) autoantibodies on the development of the spontaneous lupus nephritis of female (NZB x NZW) F1 (B x W) mice. Female and male B x W mice were immunized with rabbit renal tubular basement membrane in adjuvant at 2 months of age and their kidneys were examined 35 to 66 days later; control B x W mice were injected with adjuvant only or remained untreated. By immunofluorescent and histopathological criteria, only the 4-month-old female B x W mice with anti-GBM autoantibody deposits had an accelerated onset of lupus nephritis resembling the findings not seen until 6 to 8 months of age in unmanipulated mice. Thus potentially pathogenic amounts of immune complexes are present in young female B x W mice, but these do not deposit in glomeruli until much later in life. Evidently, the anti-GBM autoantibodies modified the glomerular milieu sufficiently to facilitate accelerated immune complex deposition.

Studies on the pathogenesis of experimental autoimmune renal tubulointerstitial disease in guinea pigs. VI. Induction of renal lesions by active or passive immunization of strain 2 guinea pigs

It has been reported that strain 2 guinea pigs do not develop experimental autoimmune renal tubulointerstitial disease (RTD) by active or passive immunization. Under our experimental conditions strain 2 guinea pigs are susceptible to the induction of RTD. Typical moderate to severe renal lesions were seen 22 days after immunization with rabbit tubular basement membrane in complete Freund's adjuvant. Most Albany strain guinea pigs had severe RTD. Susceptibility to induction of RTD by passive transfer of antitubular basement membrane autoantibodies was studied in Albany (A) and strain 2 (2) guinea pigs, as well as in A leads to A, A leads to 2, and 2 leads to A radiation chimeras. Only some strain 2 guinea pigs had mild to severe renal lesions by day 9, but by day 19 all had typical histologic renal abnormalities. Albany guinea pigs already had moderate to severe RTD by days 9-10. Strain 2 differed from Albany recipients by a noticeable delay in the onset of lesions. Bone marrow transplants between Albany and strain 2 did not affect these susceptibility differences. A leads to 2 recipients responded like strain 2, and 2 leads to A like Albany. This indicates that the delay of onset of RTD in strain 2 is not a defect in the bone marrow-derived inflammatory cells.

Renal tubulointerstitial lesions in CBA/J mice

Renal tubulointerstitial lesions (RTL) were observed with high frequency in CBA/J mice more than 2 months old. RTL were characterized by interstitial infiltrates of lymphocytes and macrophages in the corticomedullary zone. Multinucleated structures sometimes resembling giant cells were present, and there was destruction of tubules and tubular basement membranes in areas of infiltration. Glomeruli appeared normal. RTL were first seen in 12 to 22 CBA/J mice 2.5 to 3 months old. By the age of 7 to 9 months, 35 to 45 mice were affected, and all 24 mice 12 months old or older had RTL. CBA/J mice had these unique renal lesions whether they were purchased and examined immediately, were obtained as weanlings andreared in our quarters or those of another institution, or were fourth generation descendants of purchased breeders. The propensity to develop RTL has been present in this strain for at least 2 years. RTL were not observed in C57BL/6J mice housed for 14 months with affected animals or in a survey of CBA/HUmc, C57BL/6J, A/J, BALB/cJ, or C3H/HeJ mice. Immunofluorescent examination of CBA/J kidneys appears to rule out antitubular basement membrane autoantibodies or immune complexes in the pathogenesis of RTL.

Studies on the pathogenesis of experimental autoimmune renal tubulointerstitial disease in guinea-pigs. IV. failure to inhibit mononuclear cell accumulation with niridazole

Niridazole is a potent inhibitor of certain expressions of delayed-type hypersensitivity; however, its effect and specificity on other immunologically induced mononuclear cell infiltrates has not been determined. We therefore tested this drug in a model of auto-antibody-induced renal tubulointerstitial disease (RTD), which is characterized by the accumulation of lymphocytes and macrophages in the cortical interstitium. Niridazole-treated (100 mg/kg) and untreated guineapigs were injected with potent anti-tubular basement membrane serum from donors with RTD. Drug treatment was repeated 2-3 times during the course of 10 days. The characteristic renal lesions were found in both groups. However, a single dose of niridazole inhibited skin reactivity in tuberculin sensitive guinea-pigs for at least 8 days. These findings further support the contention that immunologic tissue injury in RTD does not involve mechanisms of delayed-type hypersensitivity.

C4 in glomerular lesions of NZB/NZW mice

Antisera to human C4 can discriminate circulating Ss protein (C4) levels in mice. Since there has been no information on early complement components (C1, C4, C2) in the renal lesions of B/W mice, we applied the indirect immunofluorescence technique to post-mortem sections of kidney from B/W female mice with advanced renal disease. C4 was present in fifteen of the sixteen specimens, usually in a distribution similar to that of IgG or C3. Specificity was demonstrated by differential absorptions with high-Ss serum from C57BL/6 male mice and low-Ss serum from C3H/HeJ female mice. High-Ss-absorbed antiserum did not stain, while low-Ss-absorbed antibody retained much of its activity. This finding parallels the demonstration of early complement components in lesions of clinical lupus nephritis, and is consistent with classic complement pathway activation in B/W disease.

Studies on the pathogenesis of experimental autoimmune renal tubulointerstitial disease in guinea-pigs. III. The role of adjuvants in the induction of disease

Experimental renal tubulointerstitial disease is induced in guinea-pigs by anti-tubular basement membrane autoantibodies. The complete mechanism of mononuclear cell accumulation in the target organ is not known; however, in addition to antibody, complement and radiosensitive leucocytes are important. In the present experiments we explored the influence of adjuvant in the accumulation of mononuclear cells in kidneys of actively or passively immunized guinea-pigs. We found that renal disease could be induced without adjuvant, by multiple injections of rabbit tubular basement membrane. Lesions were comparable to those groups which received a single dose of antigen in Freund's complete or pertussis vaccine adjuvant. Passive transfer of nephritis confirmed that adjuvant is not necessary for either the accumulation of mononuclear cells or the formation of antibodies with particularly potent pathogenicity.

C4 synthesis in C4-deficient guinea pig radiation chimeras: restoration of the classic complement pathway

Bone marrow transplants from normal Albany strain guinea pigs established a functional classical pathway of complement (C) in C4-deficient (C4D) guinea pigs. Seventeen days after transplant the Albany leads to C4D chimeras had detectable C4 and total hemolytic C activities. Maximum C4 levels (2 to 8% of normal were reachered by day 73 and restored total C to 40% of normal. Classical pathway function persisted for about 150 days and, thereafter, declined to undetectable levels by day 385. In contrast, Albany guinea pigs transplanted with C4D marrow maintained normal C4 levels throughout the experiment, suggesting that the C4-producing cells are radioresistant and long-lived. Unlike unmanipulated C4D animals, Albany leads to C4D chimeras were unable to produce antibodies to guinea pig C4 when immunized with normal guinea pig serum. These experiments suggest that bone marrow cell progeny produce C4 in vivo.

Synthesis of C4 by C4 Deficient NIH-Albany Strain Guinea Pig Radiation Chimeras: Restoration of the Classical Pathway of Complement

We have detected significant hemolytic C4 activity after transplant of normal guinea pig bone marrow into lethally irradiated guinea pigs genetically deficient in C4. Each of five C4-deficient guinea pigs received 640 rads total body irradiation. They were immediately injected intracardially with 93 to 200 × 106 allogeneic nucleated marrow cells from Albany strain normal guinea pigs. The recipients were followed by sequential white cell counts and titrations of total complement, C1, C4, and C2. C4 activity, initially undetectable, was present as early as 24 days after transplantation and reached maximum levels by 45 to 60 days. C4 protein was also identified by using monospecific anti-guinea pig C4 serum. Amounts of C4 were sufficient to restore classical pathway function. C1 activity, initially 2 S.D. below normal, rose dramatically to normal or greater than normal levels. C2 activity also increased. These data demonstrate that allogeneic donor stem cells protected the lethally irradiated C4-deficient recipients and these allogeneic radiation chimeras subsequently synthesize circulating functional C4.

Immune complexes in skin of NZB/NZW mice

Skin biopsies were performed on female (NZB X NZW)F1 mice (B/W) at ages ranging from 1 to 12 months. The control strain was the C57B1/6. Immunoglobulin G and beta 1C globulin deposition was sought using the indirect immunofluorescence method. Both globulins were detected consistently at the dermal-epidermal junction from the age of 6 months. The pattern of staining was granular, and progressed from focal deposition to confluent and diffuse involvement of the basement membrane at 9-10 months of age. No staining was observed in any of the C57B1/6 mice up to 14 months of age. These findings increase the resemblance of B/W disease to human systemic lupus erythematosus.

The significance of a positive cutaneous immunofluorescence test in systemic lupus erythematosus

Direct cutaneous immunofluorescence microscopical examination of uninvolved skin is an important diagnostic test in systemic lupus erythematosus. Its prognostic significance is undetermined. In twenty-four patients there was an increased incidence of leukopenia, hypocomplementaemia, and LE cells in patients with positive skin immunofluorescence. Positive cutaneous immunofluorescence of uninvolved skin was correlated with the most severe forms of lupus renal disease, membranous glomerulonephritis, and diffuse proliferative glomerulonephritis.