Mitrecin A, an endolysin-like bacteriolytic enzyme from a newly isolated soil streptomycete

An open reading frame with homology to known endolysin genes was identified in the genome of Streptomyces sp. strain 212, which is a newly isolated soil bacterium. The heterologously expressed gene product of this endolysin-like gene, called Mitrecin A, demonstrated bacteriolytic activity against several Gram-negative bacteria. The genome of the bacterial strain was sequenced to draft quality using pyrosequencing followed by genome assembly and gene annotation. Within the sequence, a chromosomally located endolysin-like open reading frame was predicted. The gene product, designated Mitrecin A, was heterologously expressed and isolated from contaminating proteins as a fusion protein to a 6-histidine tag. Mitrecin A consists of 127 amino acids arranged in modular domains of activity. It has an estimated molecular weight of 14·3 kDa and retains sequence homology to the M15C peptidase subfamily of zinc metallocarboxypeptidases. The heat-labile purified recombinant protein has an overall positive charge, has optimal catalytic activities at 26°C in solution of pH 9 with 1% saline and has bacteriolytic activity against Gram-negative bacteria of the medically important genera Aeromonas, Escherichia, Salmonella, Shigella, Vibrio and Yersinia.

Significance and Impact of the Study

The gene of a new protein antimicrobial, Mitrecin A, was discovered in the genome of a soil bacterium. The purified recombinant enzyme, resulting from heterologous over expression of the gene, was found to be tolerant of increased pH conditions and to have bacteriolytic activity against Gram-negative bacteria of the medically important genera Aeromonas, Escherichia, Salmonella, Shigella, Vibrio and Yersinia. Characterization of enzymes such as Mitrecin A from previously uncharacterized bacteria provides potential options for new biocontrol agents in medically and economically important applications like therapeutics, disinfectants, food preservatives, agricultural livestock antimicrobials, and inhibitors of biofilm production.

Assessment of faculty perception of content validity of PerioSim, a haptic-3D virtual reality dental training simulator

Haptic technology (sense of touch) along with 3D-virtual reality (VR) graphics, creating lifelike training simulations, was used to develop a dental training simulator system (PerioSim). This preliminary study was designed to evaluate whether faculty considered PerioSim realistic and useful for training and evaluating basic procedural skills of students. The haptic device employed was a PHANToM and the simulator a Dell Xeon 530 workstation with 3D, VR oral models and instruments viewed on a stereoscopic monitor. An onscreen VR periodontal probe or explorer was manipulated by operating the PHANToM for sensing lifelike contact and interactions with the teeth and gingiva. Thirty experienced clinical dental and dental hygiene faculty judged the realism of the system. A PowerPoint presentation on one screen provided instructions for the simulator use with the 3D, VR simulator on a second stereoscopic monitor viewed with 3D goggles. Faculty/practitioners found the images very realistic for teeth and instruments, but less so for gingiva. Tactile sensation was realistic for teeth but not so for gingiva. The onscreen instructions were very useful with high potential for teaching. Faculty members anticipated incorporating this device into teaching and were enthusiastic about its potential for evaluating students' basic procedural skills. This study suggests that the preliminary "evidence-of-concept" was successful and PerioSim may aid students in developing necessary dental tactile skills.

Renal flares are common in patients with severe proliferative lupus nephritis treated with pulse immunosuppressive therapy: long-term followup of a cohort of 145 patients participating in randomized controlled studies

OBJECTIVE

Immunosuppressive agents have become the standard of therapy for proliferative lupus nephritis, but some patients may relapse after discontinuing treatment. We reviewed the cases of renal flares in a cohort of patients who participated in 2 randomized controlled clinical trials at the National Institutes of Health and explored the prevalence, outcome, and predictive factors of renal flares.

METHODS

Data were obtained on 145 patients treated with pulse cyclophosphamide, pulse methylprednisolone, or the combination of both. Patients had not received immunosuppressive therapy for at least 6 months and had experienced complete or partial response according to defined criteria. Renal flares were classified as either proteinuric or nephritic based on changes in urinary protein and sediment. Most patients who experienced a flare received additional immunosuppressive therapy.

RESULTS

Seventy-three patients had a complete response, and 19 had partial response/stabilization. Forty-one of these patients (45%) experienced renal flares (nephritic in 33, proteinuric in 8) after a mean followup of 117 months; 31 of them received additional immunosuppressive therapy. The median time to renal flare was 36 months in the complete responders and 18 months in the partial responders. Eleven of the 41 patients (27%) progressed to end-stage renal disease (ESRD); 9 had nephritic flares (all severe except for 1) and 2 had proteinuric flares (1 in each responder group). Compared with patients who had a complete response, those with a partial response were more likely to experience a flare, to have a severe nephritic flare, or to progress to ESRD. Low C4 at the time of response and African American ethnicity were significant independent risk factors for renal flare, by multivariate Cox proportional hazards analysis.

CONCLUSION

Nephritic flares are common in patients with proliferative lupus nephritis, even in those with a complete response to therapy, but they do not necessarily result in loss of renal function if treated with additional immunosuppressive agents. Renal flares are an important feature of the natural history of lupus nephritis and provide an opportunity for additional preventive strategies, as well as measures of efficacy in future therapeutic trials.

Combination therapy with pulse cyclophosphamide plus pulse methylprednisolone improves long-term renal outcome without adding toxicity in patients with lupus nephritis

BACKGROUND

Controlled trials in lupus nephritis have demonstrated that cyclophosphamide therapy is superior to corticosteroid therapy alone. The long-term effectiveness and side-effect profiles of pulse immunosuppressive regimens warrant further study.

OBJECTIVE

To define the long-term risk and benefit of monthly treatment with boluses of methylprednisolone, cyclophosphamide, or both.

DESIGN

Extended follow-up (median, 11 years) of a randomized, controlled trial.

SETTING

U.S. government research hospital.

PATIENTS

82 patients with proliferative lupus nephritis.

MEASUREMENTS

Rates of treatment failure (defined as need for supplemental immunosuppressive therapy or doubling of serum creatinine concentration, or death) and adverse events.

RESULTS

In an intention-to-treat survival analysis, the likelihood of treatment failure was significantly lower in the cyclophosphamide (P = 0.04) and combination therapy (P = 0.002) groups than in the methylprednisolone group. Combination therapy and cyclophosphamide therapy alone did not differ statistically in terms of effectiveness or adverse events. Of patients who completed the protocol (n = 65), the proportion of patients who had doubling of serum creatinine concentration was significantly lower in the combination group than in the cyclophosphamide group (relative risk, 0.095 [95% CI, 0.01 to 0.842]).

CONCLUSION

With extended follow-up, pulse cyclophosphamide continued to show superior efficacy over pulse methylprednisolone alone for treatment of lupus nephritis. The combination of pulse cyclophosphamide and methylprednisolone appears to provide additional benefit over pulse cyclophosphamide alone and does not confer additional risk for adverse events.

Do DNA vaccines induce autoimmune disease?

This report examines whether plasmid DNA vaccines induce the production of anti-DNA or anti-muscle cell autoantibodies. A three-fold increase in the number of B cells secreting immunoglobulin G (IgG) anti-DNA autoantibodies was detected in BALB/c mice immunized and boosted with any of three DNA plasmids (p < 0.004). This correlated with a transient increase in serum anti-DNA autoantibody titers but was not associated with the development of glomerulonephritis or autoimmune disease. None of the DNA vaccines examined stimulated the production of anti-muscle cell autoantibodies or the development of myositis. The effect of DNA vaccines on the development of nascent autoimmunity in lupus-prone (NZB x NZW)F1 mice was also examined. Repeated vaccination did not alter the onset or course of disease in these animals. These findings suggest that DNA vaccines neither initiate nor accelerate the development of systemic autoimmunity.

Testing mode and surface treatment effects on dentin bonding

The goal of this project was to evaluate the effect of the following variables on shear dentin-bonding test results: mode of testing (cyclic fatigue versus static loading), surface treatments (32% phosphoric acid, 10% phosphoric acid, and no treatment [unetched]), and type of shear test (traditional planar versus push-out). All teeth were stored in distilled water and tested in a shear mode at a loading rate of 2 mm/ min. The specimens were loaded in static or cycled for 1000 cycles using a staircase approach or until fracture, whichever occurred first. On samples with etched dentin surfaces, the push-out test did not demonstrate a significant difference in measured bond strength when compared with results from the planar test, although sample preparation was more labor-intensive. The bond strength resulting from cyclic fatigue of the etched specimens was approximately 51% of the static loading value. Ten percent phosphoric acid was as effective as 32% phosphoric acid for dentin bonding. Finite-element analysis indicated that the traditional planar shear test produces flexure of the specimen and high tensile stress magnitudes within the resin bonding layer. The push-out test produces elevated compressive stresses localized in the composite along the circumference of the punch. Shear stresses in the resin bonding layer are similar for both testing methods at the same loading element contact force.

Methylprednisolone and cyclophosphamide, alone or in combination, in patients with lupus nephritis. A randomized, controlled trial

BACKGROUND

Uncertainty exists about the efficacy and toxicity of bolus therapy with methylprednisolone or of the combination of methylprednisolone and cyclophosphamide in the treatment of lupus nephritis.

OBJECTIVE

To determine 1) whether intensive bolus therapy with methylprednisolone is an adequate substitute for bolus therapy with cyclophosphamide and 2) whether the combination of methylprednisolone and cyclophosphamide is superior to bolus therapy with methylprednisolone or cyclophosphamide alone.

DESIGN

Randomized, controlled trial with at least 5 years of follow-up.

SETTING

Government referral-based research hospital.

PATIENTS

82 patients with lupus nephritis who had 10 or more erythrocytes per high-power field, cellular casts, proteinuria (> 1 g of protein per day), and a renal biopsy specimen that showed proliferative nephritis.

INTERVENTIONS

Bolus therapy with methylprednisolone (1 g/m2 body surface area), given monthly for at least 1 year; bolus therapy with cyclophosphamide (0.5 to 1.0 g/m2 body surface area), given monthly for 6 months and then quarterly; or bolus therapy with both methylprednisolone and cyclophosphamide.

MEASUREMENTS

1) Renal remission (defined as < 10 dysmorphic erythrocytes per high-power field, the absence of cellular casts, and excretion of < 1 g of protein per day without doubling of the serum creatinine level), 2) prevention of doubling of the serum creatinine level, and 3) prevention of renal failure requiring dialysis.

RESULTS

Renal remission occurred in 17 of 20 patients in the combination therapy group (85%), 13 of 21 patients in the cyclophosphamide group (62%), and 7 of 24 patients in the methylprednisolone group (29%) (P < 0.001). Twenty-eight patients (43%) did not achieve renal remission. By life-table analysis, the likelihood of remission during the study period was greater in the combination therapy group than in the methylprednisolone group (P = 0.028). Combination therapy and cyclophosphamide therapy were not statistically different. Adverse events were amenorrhea (seen in 41% of the cyclophosphamide group, 43% of the combination therapy group, and 7.4% of the methylprednisolone group), cervical dysplasia (seen in 11% of the cyclophosphamide group. 7.1% of the combination therapy group, and 0% of the methylprednisolone group), avascular necrosis (seen in 11% of the cyclophosphamide group, 18% of the combination therapy group, and 22% of the methylprednisolone group), herpes zoster (seen in 15% of the cyclophosphamide group, 21% of the combination therapy group, and 3.7% of the methylprednisolone group) and at least one infection (seen in 26% of the cyclophosphamide group. 32% of the combination therapy group, and 7.4% of the methylprednisolone group).

CONCLUSIONS

Monthly bolus therapy with methylprednisolone was less effective than monthly bolus therapy with cyclophosphamide. A trend toward greater efficacy with combination therapy was seen.

Platelet association with gingival tissue inflammation

Platelets (PL) may be involved in the inflammatory process through the release of a variety of factors which could contribute to gingival tissue injury. Thus, conditions which result in the localized discharge of PL constitutents could lead to amplification of the inflammatory process at these sites. The purpose of this study was to determine if there was evidence of PL activation in gingival crevicular fluid and whether the degree of gingival inflammation, as measured by the gingival index (GI), was associated with the degree of platelet activation. This was monitored by assaying for beta-thromboglobulin (beta-TG), a platelet specific protein released from alpha granules of PL when activated. One uL samples of the fluids were obtained from human subjects from gingival sites with various GI scores. Fluid samples were also obtained at probe-induced bleeding gingival crevicular sites. beta-TG levels in the various fluids obtained from the crevice were determined by radioimmunoassay (RIA). The RIA data indicated that detectable beta-TG levels were observed in all samples, the means ranging from 5.5 ng/ml to 45.2 ng/ml. Additionally, a positive association between the GI scores of 0 and 1 and the beta-TG levels where observed. For GI scores of 2 and above the beta-TG concentrations appeared to approach a maximum value. These findings provide evidence for PL activation and suggest a relationship with gingival inflammation.

Complexity of the cytokine and antibody response elicited by immunizing mice with Plasmodium yoelii circumsporozoite protein plasmid DNA

The number, type, and location of cytokine- and Ab-secreting cells activated in mice immunized and boosted with plasmid DNA encoding the circumsporozoite protein of the malarial parasite Plasmodium yoelii (PyCSP) were monitored. The initial humoral response was localized to the draining lymph nodes and was characterized by production of IgG1 anti-PyCSP Abs and the Th2 cytokine IL-4. In contrast, the secondary response was dominated by IFN-gamma production (a Th1 cytokine) and the secretion of IgG2a anti-PyCSP Abs in the spleen. PyCSP DNA and mRNA were detected only in the quadriceps muscles (sites of plasmid injection), yet these sites lacked either cytokine- or Ab-secreting cells. These findings indicate that circulating lymphocytes encounter plasmid-encoded Ag in the muscle bed, initiate a humoral response in the draining lymph nodes, and then seed distal lymphoid organs. Profound differences were observed between the primary and secondary immune responses induced by plasmid immunization, which may influence vaccine efficacy.

Complexity of the cytokine and antibody response elicited by immunizing mice with Plasmodium yoelii circumsporozoite protein plasmid DNA

The number, type, and location of cytokine- and Ab-secreting cells activated in mice immunized and boosted with plasmid DNA encoding the circumsporozoite protein of the malarial parasite Plasmodium yoelii (PyCSP) were monitored. The initial humoral response was localized to the draining lymph nodes and was characterized by production of IgG1 anti-PyCSP Abs and the Th2 cytokine IL-4. In contrast, the secondary response was dominated by IFN-gamma production (a Th1 cytokine) and the secretion of IgG2a anti-PyCSP Abs in the spleen. PyCSP DNA and mRNA were detected only in the quadriceps muscles (sites of plasmid injection), yet these sites lacked either cytokine- or Ab-secreting cells. These findings indicate that circulating lymphocytes encounter plasmid-encoded Ag in the muscle bed, initiate a humoral response in the draining lymph nodes, and then seed distal lymphoid organs. Profound differences were observed between the primary and secondary immune responses induced by plasmid immunization, which may influence vaccine efficacy.

Characterization of in vivo mutated T cell clones from patients with systemic lupus erythematosus

Patients with systemic lupus erythematosus (SLE) have increased percentages of activated T cells and increased numbers of cells with mutations in their hypoxanthineguanine phosphoribosyltransferase (hprt) gene, as judged by growth in the presence of 6-thioguanine. To study the relevance of these mutant T cells to disease pathogenesis, we have assessed the phenotype and functional capabilities of such cells from 21 patients with SLE who never had received cytotoxic drugs. The frequency of T cells with mutations in hprt in the blood of these patients ranged from normal to 25 times normal (mean +/- SEM [21.1 +/- 6.1] x 10(-6) versus [4.8 +/- 0.8] x 10(-6), in 15 age-matched normal individuals, P < 0.001) and correlated significantly with disease duration. CD4+ and CD8+ phenotypes were comparable among mutated and nonmutated clones from both patients and normals. Although the frequency of CD3+CD4-CD8- cells was low, it was increased among SLE-derived T cells (mutated and wild-type) compared with clones derived from normals (5% for SLE vs 1% for normals). A substantial percentage of all clones were able to help autologous B cells to produce anti-ssDNA, 11 of 68 (16%) selected clones and 3 of 28 (11%) nonselected clones. Help for autoantibody production was confined to CD4+ SLE-derived T cell clones. It could be blocked using an anti-HLA-DR mAb, suggesting that classical cognate help was operative. This represents the first estimate of the frequency of T cells able to drive autoantibody production in SLE.

Increased utilization of polyreactive B cells during periods of generalized immune activation

This work examines the hypothesis that B cells secreting polyreactive antibodies (antibodies capable of binding to more than one self or foreign antigen) are preferentially utilized during periods of generalized immune stimulation. Four conditions characterized by such stimulation were examined: chronic virus infection, mitogen treatment, autoimmune disease and neonatal repertoire development. In normal adult mice, polyreactive IgM secreting lymphocytes constituted 8-9% of the actively expressed repertoire. Under conditions of generalized immune activation, this frequency increased to 13-19% (p. < .01). Polyreactive IgG secreting B cells, which were present at frequencies of < 0.5% in normal adult mice, were found at freqeuncies of 6-10% in mice with autoimmune disease, chronic virus infection or following mitogen treatment (p. < .001). We postulate that polyreactive lymphocytes are preferentially activated when the immune system is confronted with stimuli inadequately controlled by antigen-specific responses.

Systemic lupus erythematosus: theories of pathogenesis and approach to therapy

Human systemic lupus is a heterogeneous disorder characterized by multisystem inflammatory disease and the production of a variety of autoantibodies. For many years, in our ignorance, we had the freedom to imagine numerous abnormalities which might give rise to lupus: defects of the immune system, viruses, major histocompatibility driven predispositions, complement or complement receptor defects, biochemical abnormalities, impaired DNA repair, sex hormone imbalances, and many others. Now, the basis for lupus in lpr/lpr mice has been uncovered: a mutation in fas. The normal Fas cell surface molecule is important in programmed cell death, apoptosis. The lpr-associated defect in Fas interferes with normal apoptosis, allowing persistence of self-reactive lymphocytes. This finding is especially exciting to those of us who have stressed lupus-associated defects in tolerance. It also illustrates the apparent antigen-nonspecific nature of an etiologic abnormality leading to lupus. The multigenic NZB disorder is less well dissected. Recent work points to defects in an unusual bone marrow progenitor population. Patients with systemic lupus erythematosus may have different and multiple pathogenic factors, including those listed above. We recently have found that some patients with lupus have persistence of T cells with random mutations, consistent with prior abnormal activation and, perhaps, impaired apoptosis. Future therapies of patients must consider both the heterogeneity and the multifactorial pathogenesis of the syndrome we call "lupus."

Studies of marrow progenitor abnormalities in lupus-prone mice. II. Further studies of NZB Thy 1(neg)Lin(neg) bone marrow cells

Bone marrow cells from NZB mice were fractionated and enriched in cells lacking surface markers characteristic of mature lineages, termed Thy 1neg Lineage(neg) cells. These cells represent approximately 1% of all marrow cells and constitute a much greater fraction of the bone marrow than do Thy 1lo Lineage(neg) cells. The NZB Thy 1neg Lineage(neg) cells were able to protect nonautoimmune, histocompatible DBA/2 recipients from lethal doses of irradiation, suggesting that this subpopulation contained progenitor cells. Consistent with this observation, fractioned Lip 6+ Thy 1neg Lineage(neg) cells, representing early B lineage cells, were less effective than Lip 6neg Thy 1neg Lineage(neg) cells in radioprotection. NZB marrow contains a great many more CFU-S than does marrow from nonautoimmune strains. DBA/2 mice transplanted with Thy 1neg Lineage(neg) cells from NZB marrow had substantial numbers of CFU-S, much greater than controls. This CFU-S potential was found primarily in the Lip 6neg Thy 1neg Lineage(neg) fractionated marrow, suggesting that that population contained early progenitor cells that had not yet differentiated into B lineage cells. Both radioprotection and increased CFU-S were transmitted serially by bone marrow from DBA/2 recipients of Thy 1neg Lineage(neg) NZB marrow to secondary and tertiary (irradiated) DBA/2 recipients. Also serially transplanted were precursors of antibody forming cells. These findings suggest that NZB Thy 1neg Lineage(neg) marrow cells play a critical role in the development of the abnormal phenotype of NZB mice. However, because this probably is not a homogeneous population, additional work will be necessary to define the surface and molecular properties of the cell or cells within the NZB Thy 1neg Lineage(neg) marrow population which serve as progenitors of the cells which mediate NZB disease.

Modulation of the expression of murine lupus by gonadotropin-releasing hormone analogs

Recent studies have suggested that hypothalamic and pituitary hormones may directly influence the immune system. One such hormone with immunomodulatory properties is GnRH. We hypothesized that GnRH and/or the gonadotropins might alter the severity of autoimmune disease through mechanisms distinct from their effects on gonadal hormones. This possibility was tested in a murine model of lupus. We assessed disease severity over time in intact and castrated, male and female, lupus-prone (SWR x NZB) F1 hybrid mice during treatment with GnRH agonist, GnRH antagonist, or vehicle. Compared to vehicle administration, GnRH antagonist administration significantly decreased total serum immunoglobulin G and anti-DNA antibodies in castrated male and female mice and significantly improved survival. In contrast, GnRH agonist administration exerted reciprocal effects in castrated mice, leading to early increases in serum anti-DNA and total immunoglobulin G levels. We conclude that GnRH and/or the gonadotropins can modify the expression of murine lupus independently of their regulation of gonadal steroid secretion.

Role of endogenous retroviruses in autoimmune diseases

Retroviruses have been implicated in the pathogenesis of murine and human lupus; however, many positive findings have been followed by alternative explanations. Initial findings implicating xenotropic retroviruses were subsequently invalidated. The first solid demonstration that endogenous retroviruses mediate disease was the study of SL/Ni mice. Here budding ecotropic retroviral particles from arterial smooth muscle cells caused an antibody response to the particles with subsequent complement deposition. Our laboratory has focused on derangements in endogenous MCF retroviral expression. We found that lupus-prone NZB, BXSB and MRL strains have a marked increase in expression of Mpmv RNA in their thymuses while bone marrow expression did not differ from normal strains. Sequence analysis demonstrated mutations in the NZB endogenous retroviruses which could alter expression. A phosphorothioate antisense oligonucleotide to the initiation sequence of Mpmv caused lymphocyte activation in vivo in normal mice, providing further evidence for in vivo effects of Mpmv and potential for pathological abnormalities in lupus-prone strains.

MRL-lpr/lpr disease: theories meet Fas

It has been exciting for scientists to postulate all sorts of derangements to explain the numerous observations regarding the disease of MRL-lpr/lpr mice. Until recently, our imaginations have had almost free reign, unconstrained by any true knowledge. Now, however, it has been found that the lpr gene represents a mutation which causes a defect in a cell surface molecule, Fas. Since the normal Fas is thought to be important in programmed cell death, apoptosis, the lpr-associated defect in Fas is thought to interfere with normal apoptosis. Therefore, we are forced to reconsider all hypotheses regarding lpr/lpr mice in terms of a defect in Fas. This paper represents such an attempt. It suggests that failure of peripheral apoptosis of CD4+ cells allows self-reactive helper T cells to persist and drive autoantibody production. Failure of apoptosis of self-reactive CD8+ cells leads to down-regulation of CD8 and persistence as CD4-, CD8- T cells which contribute to the lymphadenopathy.

Assessment of clinical parameters associated with increased frequency of mutant T cells in patients with systemic lupus erythematosus

OBJECTIVE

To determine the clinical features that contribute to an increased frequency of mutant T cells (FMC) in patients with systemic lupus erythematosus (SLE).

METHODS

During in vivo T cell division, there are errors in replication which give rise to mutations throughout the genome. An estimate of such mutations may be obtained by focusing on mutations in the hprt gene, which can be screened by assessing relative growth of T cell clones in the presence and absence of 6-thioguanine. In this study, peripheral blood T cell clones from 47 patients with SLE were assessed, and the frequency of mutant T cells (FMC) determined. An attempt was made to correlate the FMC with disease measures.

RESULTS

Patients with SLE had a spectrum of FMC values, ranging from normal to almost 1,000 times normal. Total duration of active disease (rs = 0.94), past highest disease activity index (rs = 0.80), and number of lupus flares (rs = 0.76) correlated most strongly (P < 0.0001) with FMC by Spearman's rank order analysis. In contrast, current disease activity index and current anti-DNA level did not correlate with FMC. Similar correlations between FMC and cumulative past lupus disease activity were found by linear regression analysis (rp = 0.89 for the correlation between the natural logarithm of FMC and cumulative duration of active disease). By both statistical tests, therapy was found to be only a minor contributor to FMC.

CONCLUSION

In our patient population, a high FMC value appears to reflect cumulative clinical lupus disease activity, involving both intensity and duration of past active disease.

Cross-reactivity of IgG anti-DNA-secreting B cells in patients with systemic lupus erythematosus

This study is the first to analyze the cross-reactivity of in vivo activated B cells from patients with systemic lupus erythematosus. A chamber ELIspot assay was used to determine whether lymphocytes secreting antibodies that bound to DNA or 2,4,6-trinitrophenol (TNP)-keyhole limpet-hemocyanin (KLH) could simultaneously bind to the unrelated antigens actin or ovalbumin. IgM anti-DNA-, IgM anti-TNP-KLH- and IgG anti-TNP-KLH-secreting B cells from patients and controls showed similar levels of cross-reactivity (ranging from 6% to 23%, depending upon the antibody isotype and antigen pair examined). In general, IgG-producing cells were less cross-reactive than IgM producers from the same individual (on the average threefold, p < 0.001). In contrast, IgG anti-DNA-secreting B cells from lupus patients (i) showed no decrease in cross-reactivity when compared to IgM anti-DNA-secreting cells and (ii) were significantly more cross-reactive than control IgG anti-DNA-secreting cells and IgG anti-TNP-KLH secreting cells from patients (p < 0.001). The degree of IgG anti-DNA cross-reactivity correlated with disease activity (r = 0.52, p < 0.02). The implications of these findings with respect to repertoire expression and disease pathogenesis are discussed.

Have animal data been used inappropriately to estimate risks to humans from environmental trichloroethylene?

Trichloroethylene (TCE) is widely viewed as an environmental hazard. Its major metabolite, chloral hydrate, is a currently used medicine. Regulation of TCE is based on a linear extrapolation from effects of high doses in rodents to risks for humans at low doses. However, metabolic, toxicologic, and epidemiologic data on trichloroethylene and chloral hydrate as well as water chlorination studies call this approach into question. The mechanism of carcinogenesis of TCE and chloral hydrate in rodents is nonlinear: very high doses, sufficient to cause cellular necrosis, are necessary. Malignancy arises from repeated cycles of necrosis and regeneration with the ultimate emergence of hyperplasia and then neoplasia. Metabolites of TCE, trichloroacetic acid and dichloroacetic acid, mediate this toxic effect of TCE. These chloroacetic acids also induce similar lesions in rodents given high doses of the medicine, chloral hydrate. Human epidemiologic data show no increase in mortality or malignancy from substantial chronic exposure to trichloroethylene. Chlorination of drinking water produces much higher levels of chloroacetic acids than could be obtained from metabolizing TCE under current regulations. We conclude that the assumptions underlying current regulations are not applicable to TCE. Instead of a straight-line extrapolation model, a threshold model may be more appropriate. The data suggest that it is possible to increase substantially the allowable trichloroethylene in drinking water without increasing health hazards.

Should chloral hydrate be banned?

OBJECTIVE

Current federal regulations of potentially carcinogenic environmental chemicals are based on the assumption that risks for humans can be extrapolated from the effects of chronic high-dose exposure of rodents. It is assumed that all chemicals induce cancer by a genotoxic mechanism (direct interaction with DNA) and that humans metabolize chemicals by the same pathways as the test rodents. Trichloroethylene, a former medicine, is now regulated because of rodent studies. Its major metabolite, chloral hydrate, widely used as a sedative in both adults and children, is in danger of being banned by comparable studies. This paper assesses the safety of chloral hydrate.

DESIGN

Analysis of the literature regarding the metabolic, toxicologic, and epidemiologic data on trichloroethylene and chloral hydrate.

RESULTS

The dose-response relationship for carcinogenesis of chloral hydrate and other chemicals in its metabolic breakdown pathway is nonlinear in rodents: very high doses given chronically, sufficient to cause cellular necrosis, are necessary for induction of malignancies. In addition, epidemiologic data on people exposed to substantial amounts of trichloroethylene (which is metabolized to chloral hydrate) show no increase in mortality or cancers.

CONCLUSIONS

The assumptions underlying current regulatory practices for environmental chemicals are not applicable to the medicinal use of chloral hydrate. Instead, a threshold model is appropriate. The data do not suggest the need to ban chloral hydrate as a medicine; however, possible modifications in its use are suggested.

Administration of a phosphorothioate oligonucleotide antisense to murine endogenous retroviral MCF env causes immune effects in vivo in a sequence-specific manner

Previous in vitro studies had suggested that a product of the env gene of murine MCF (polytropic)-related sequences plays a role in regulating lymphocyte activation. To determine whether such an effect occurs in vivo, we have studied mice injected with phosphorothioate oligonucleotides antisense to such sequences. Injection of mice with antisense to the initiation region of the env gene resulted in (i) increased spleen cell numbers, primarily due to an increase in splenic B cells, (ii) increased class II MHC expression on B cells, (iii) increased RNA and DNA synthesis, and (iv) increased numbers of Ig producing cells. These results obtained with the antisense to MCF-related env did not occur with two scrambled phosphorothioate oligonucleotides or with antisense oligonucleotides to the initiation region of the env gene of xenotropic or ecotropic retroviral sequences. These data suggest that products of certain endogenous retroviral sequences regulate lymphocyte activation in vivo.

Studies of T cell deletion and T cell anergy following in vivo administration of SEB to normal and lupus-prone mice

This study examines the responses of lupus-prone NZB, (NZB x NZW) F1, BXSB, MRL-lpr/lpr and control mice (H-2 and Mls matched) to in vivo administration of the superantigen staphylococcal enterotoxin B (SEB). Two weeks after i.v. administration of 500 micrograms SEB, CD4+V beta 8+ lymph node T cells were deleted equivalently by lupus-prone and control mice. However, IE+ strains deleted a greater proportion (47% to 77%) of their CD4+V beta 8+ cells than did IE- strains (24% to 27%). CD8+V beta 8+ cells were deleted less than CD4+V beta 8+ cells by injection of 500 micrograms SEB. IE- strains failed to delete CD8+V beta 8+ cells, whereas six of seven IE+ strains deleted > 25% of their CD8+V beta 8+ cells. IE+ MRL-lpr/lpr mice showed some impairment in deletion: they failed to delete CD8+V beta 8+ cells at all doses of SEB and had reduced deletion of CD4+V beta 8+ cells at low doses of in vivo SEB (10 and 50 micrograms). Peripheral expansion of the intrathymically deleted V beta 7 TCR family was not observed in lupus-prone mice 2 wk after 500 micrograms in vivo SEB. In vitro restimulation with SEB of mice previously injected with 500 micrograms SEB demonstrated anergy in T cells from all strains, including the IE- and MRL-lpr/lpr. This result contrasts with previous reports of tolerance defects in lupus-prone strains using B cell read-out assays as measures of tolerance. The present study demonstrates that there is no global defect in peripheral T cell deletion or anergy in lupus-prone mice to the superantigen SEB. Although additional Ag would need to be studied, these experiments raise the possibility that some reported tolerance defects in lupus-prone strains may reflect excessive B cell responses to relatively normal T cell signals.

Studies of T cell deletion and T cell anergy following in vivo administration of SEB to normal and lupus-prone mice

This study examines the responses of lupus-prone NZB, (NZB x NZW) F1, BXSB, MRL-lpr/lpr and control mice (H-2 and Mls matched) to in vivo administration of the superantigen staphylococcal enterotoxin B (SEB). Two weeks after i.v. administration of 500 micrograms SEB, CD4+V beta 8+ lymph node T cells were deleted equivalently by lupus-prone and control mice. However, IE+ strains deleted a greater proportion (47% to 77%) of their CD4+V beta 8+ cells than did IE- strains (24% to 27%). CD8+V beta 8+ cells were deleted less than CD4+V beta 8+ cells by injection of 500 micrograms SEB. IE- strains failed to delete CD8+V beta 8+ cells, whereas six of seven IE+ strains deleted &gt; 25% of their CD8+V beta 8+ cells. IE+ MRL-lpr/lpr mice showed some impairment in deletion: they failed to delete CD8+V beta 8+ cells at all doses of SEB and had reduced deletion of CD4+V beta 8+ cells at low doses of in vivo SEB (10 and 50 micrograms). Peripheral expansion of the intrathymically deleted V beta 7 TCR family was not observed in lupus-prone mice 2 wk after 500 micrograms in vivo SEB. In vitro restimulation with SEB of mice previously injected with 500 micrograms SEB demonstrated anergy in T cells from all strains, including the IE- and MRL-lpr/lpr. This result contrasts with previous reports of tolerance defects in lupus-prone strains using B cell read-out assays as measures of tolerance. The present study demonstrates that there is no global defect in peripheral T cell deletion or anergy in lupus-prone mice to the superantigen SEB. Although additional Ag would need to be studied, these experiments raise the possibility that some reported tolerance defects in lupus-prone strains may reflect excessive B cell responses to relatively normal T cell signals.

In-vivo comparisons of clot formation on titanium and hydroxyapatite-coated titanium

We investigated in vivo clot formation on the surface of hydroxyapatite (HA)-coated titanium (Ti) implants and on non-coated Ti implants. Immediately after tooth extraction implant samples were inserted into the blood clot, in the same extraction site, for 1, 30, 60, or 120 seconds. Samples were processed for scanning electron microscopy (SEM). Qualitative observations of clotting topography were made by direct SEM viewing. Neither of the implant surfaces appeared to differ markedly in the degree of clotting during the 120 seconds of implantation; they revealed very early clot formation and limited clot attachment. These results were compared to the findings obtained in a previous study using identical methods with an intact periodontal ligament (PDL), root planed roots, and roots planed and treated with pH 1 citric acid. The PDL surface had the most rapid clot formation at all time periods. By 120 seconds, all root surfaces had completed clot formation.

Heterogeneous expression and coordinate regulation of endogenous retroviral sequences in human peripheral blood mononuclear cells

This study examines the expression of human endogenous retroviral or retroviral-like (ERV) sequences in peripheral blood mononuclear cells (PBMC). Probes to 12 human ERV were used in Northern analyses of 38 patients with autoimmune muscle diseases and 31 blood donor controls. All patients and controls expressed multiple classes of ERV RNA. This expression was quite heterogenous: for each of the nine ERV classes for which expression was detected, some individuals showed high RNA levels whereas others showed low levels. ERV expression was independent of disease and autoantibody production. Statistical analysis of densitometric data indicated that expression of several classes of ERV was coordinately regulated. ERV expression in individual patients showed coordinate fluctuations with time. These studies demonstrate the heterogeneity and coordinate regulation of human ERV expression. To evaluate whether ERV expression might be affected by lymphocyte activation, PBMC were cultured with or without lymphocyte mitogens before RNA extraction. These studies demonstrated complex changes in ERV expression after lymphocyte activation. Murine ERV have several immunoregulatory activities. If human ERV have analogous effects, their heterogeneous expression and association with lymphocyte activation may have important biologic consequences.

Controlled trial of pulse methylprednisolone versus two regimens of pulse cyclophosphamide in severe lupus nephritis

Pulse cyclophosphamide is more effective than prednisone alone in preventing renal failure in lupus nephritis. We undertook a randomised, controlled trial to find out whether pulse methylprednisolone could equal pulse cyclophosphamide in preserving renal function in patients with lupus nephritis, and whether there was a difference between long and short courses of pulse cyclophosphamide in preventing exacerbations. 65 patients (60 female, 5 male; median [range] age 29 [10-48] years) with severe lupus nephritis were assigned randomly to monthly pulse methylprednisolone for 6 months (25 patients), monthly pulse cyclophosphamide for 6 months (20), or monthly cyclophosphamide for 6 months followed by quarterly pulse cyclophosphamide for 2 additional years (20). Patients treated with pulse methylprednisolone had a higher probability of doubling serum creatinine than those treated with long-course cyclophosphamide (p less than 0.04). Risk of doubling creatinine was not significantly different between short and long course cyclophosphamide. However, patients treated with short-course cyclophosphamide had a higher probability of exacerbations than those treated with long-course cyclophosphamide (p less than 0.01). An extended course of pulse cyclophosphamide is more effective than 6 months of pulse methylprednisolone in preserving renal function in patients with severe lupus nephritis. Addition of a quarterly maintenance regimen to monthly pulse cyclophosphamide reduces the rate of exacerbations.

A linkage map of mouse chromosome 1 using an interspecific cross segregating for the gld autoimmunity mutation

An interspecific backcross was used to define a high resolution linkage map of mouse Chromosome (Chr) 1 and to analyze the segregation of the generalized lymphoproliferative disease (gld) mutation. Mice homozygous for gld have multiple features of autoimmune disease. Analysis of up to 428 progeny from the backcross [(C3H/HeJ-gld x Mus spretus)F1 x C3H/HeJ-gld] established a map that spans 77.6 cM and includes 56 markers distributed over 34 ordered genetic loci. The gld mutation was mapped to a less than 1 cM segment on distal mouse Chr 1 using 357 gld phenotype-positive backcross mice. A second backcross, between the laboratory strains C57BL/6J and SWR/J, was examined to compare recombination frequency between selected markers on mouse Chr 1. Significant differences in crossover frequency were demonstrated between the interspecific backcross and the inbred laboratory cross for the entire interval studied. Sex difference in meiotic crossover frequency was also significant in the laboratory mouse cross. Two linkage groups known to be conserved between segments of mouse Chr 1 and the long arm of human Chrs 1 and 2 where further defined and a new conserved linkage group was identified that includes markers of distal mouse Chr 1 and human Chr 1, bands q32 to q42.

Mapping of a gene causing familial Mediterranean fever to the short arm of chromosome 16

BACKGROUND

Familial Mediterranean fever is an autosomal-recessive disease characterized by acute attacks of fever with sterile peritonitis, pleurisy, or synovitis. The biochemical basis of the disease is unknown, but determining the chromosomal location of the gene for the disorder should be a first step toward defining the biochemical events.

METHODS AND RESULTS

As part of a systematic genome-wide search, we sought evidence of linkage between familial Mediterranean fever and chromosome 16 DNA markers in 27 affected non-Ashkenazi Jewish families from Israel. Two loci from the subtelomeric region of the short arm of chromosome 16 (16p) had lod scores sufficient to establish linkage (a score greater than or equal to 3). One DNA marker (D16S84) gave a maximal lod score of 9.17 (odds of 10(9.17) to 1 in favor of linkage) at a recombination frequency (theta) of 0.04. A probe associated with the hemoglobin alpha complex (5'HVR) gave a maximal lod score of 14.47 at a theta of 0.06. Multipoint linkage analysis indicated that the following was the most likely gene order: the centromere, the gene for familial Mediterranean fever, D16S84, hemoglobin alpha, and the telomere. The maximal multipoint lod score was 19.86. There was a striking degree of homozygosity at chromosome 16p loci in the affected offspring of eight consanguineous couples.

CONCLUSIONS

The gene that causes familial Mediterranean fever in non-Ashkenazi Jews maps to the short arm of chromosome 16.

Studies of bone marrow progenitor cells in lupus-prone mice. I. NZB marrow cells demonstrate increased growth in Whitlock-Witte culture and increased splenic colony-forming unit activity in the Thy-1-, lineage- population

Previous studies have demonstrated that NZB marrow can transfer features of autoimmunity. Therefore, we undertook a study of NZB marrow to determine whether it demonstrated any phenotypic abnormalities. In Whitlock-Witte cultures, NZB marrow cells generated nonadherent cells at low seeding densities, densities at which marrow from other strains did not generate nonadherent cells. In contrast, NZB marrow grew less well than controls in Dexter cultures. Inasmuch as the latter favor growth of granulocyte-macrophage precursors and the former B cells, these results suggest a possible skewing of NZB marrow cells toward lymphocyte production. Unfractionated marrow cells from NZB mice were found to produce 10-fold more splenic colonies in lethally irradiated recipients than marrow cells from control mice. This result was independent of the genotype of the recipient. When the progenitor Thy-1lo, Lin- marrow subpopulation was studied, NZB mice did not differ substantially from controls regarding splenic CFU. Therefore, Thy-1-, Lin- marrow cells were studied as a possible source of the excess splenic CFU in NZB mice. Indeed, the NZB Thy-1-, Lin- population contained 30-fold more splenic CFU than did the Thy-1-, Lin- population from control mice. These results suggest that NZB mice have unusual marrow progenitor cells; such cells may play a role in their autoimmune disease.

Studies of bone marrow progenitor cells in lupus-prone mice. I. NZB marrow cells demonstrate increased growth in Whitlock-Witte culture and increased splenic colony-forming unit activity in the Thy-1-, lineage- population

Previous studies have demonstrated that NZB marrow can transfer features of autoimmunity. Therefore, we undertook a study of NZB marrow to determine whether it demonstrated any phenotypic abnormalities. In Whitlock-Witte cultures, NZB marrow cells generated nonadherent cells at low seeding densities, densities at which marrow from other strains did not generate nonadherent cells. In contrast, NZB marrow grew less well than controls in Dexter cultures. Inasmuch as the latter favor growth of granulocyte-macrophage precursors and the former B cells, these results suggest a possible skewing of NZB marrow cells toward lymphocyte production. Unfractionated marrow cells from NZB mice were found to produce 10-fold more splenic colonies in lethally irradiated recipients than marrow cells from control mice. This result was independent of the genotype of the recipient. When the progenitor Thy-1lo, Lin- marrow subpopulation was studied, NZB mice did not differ substantially from controls regarding splenic CFU. Therefore, Thy-1-, Lin- marrow cells were studied as a possible source of the excess splenic CFU in NZB mice. Indeed, the NZB Thy-1-, Lin- population contained 30-fold more splenic CFU than did the Thy-1-, Lin- population from control mice. These results suggest that NZB mice have unusual marrow progenitor cells; such cells may play a role in their autoimmune disease.

Molecular aspects of systemic lupus erythematosus: murine endogenous retroviral expression

Systemic lupus erythematosus is an immune-mediated disease in which the etiology is unknown. Full-length (8.4 kb), type C, modified polytropic (Mpmv) retroviral transcripts from the thymus are characteristic of murine lupus. Reciprocal bone marrow transplantation studies determined that this thymic expression maps to the pre-T bone marrow stem cell. In vitro and in vivo oligonucleotide antisense work suggest that type C retroviruses play a role in immune activation. This paper summarizes our studies of endogenous retroviruses in murine lupus.

Concepts of pathogenesis of systemic lupus erythematosus

It is likely that different disease-inducing factors interfere with normal immune regulatory processes in different patients (1, 3). Some people may have such a strong genetic predisposition to disease that environmental insults may not be very important. Other individuals, with a much weaker genetic predisposition, may require strong environmental stimulation for disease induction (2). Defects in self-tolerance mechanisms could provide the genetic basis of disease or the target for environmental triggers. However, induction and perpetuation of pathogenic autoantibody production may frequently be a "multi-hit" process. The greater the number and/or degree of abnormalities (genetic and environmental), the greater the probability of disease.

Timing of immunosuppression in the natural history of autoimmune diseases

We have insufficient data to guide us to the optimal timing of immunosuppression in the natural history of any autoimmune disease. Moreover, there are differences among the many autoimmune diseases and the many drugs available for use. Nevertheless, certain principles have emerged. Prophylactic non-specific immunosuppression prior to the onset of the immune-mediated process often is of minimal benefit. Vigorous immunosuppression shortly after the onset of the immune-mediated process is most effective; many agents are of benefit at such times. If the disease has progressed to substantial clinical involvement, certain drugs previously useful may no longer be effective. At such a time of moderately advanced clinical involvement, only selected agents may suppress the disease. With substantial loss of function of irreplaceable organs, or parts thereof, immunosuppression becomes progressively less effective. Such drugs can interfere with inflammatory processes, but are of little benefit after deletion of cells or scarring of an organ. Therefore, to have any benefit, immunosuppression must be instituted prior to the time of irreversible loss of critical organs or parts thereof.

Assessment of in vivo frequency of mutated T cells in patients with systemic lupus erythematosus

The frequency of mutant T cells (FMC) in blood lymphocytes from patients with systemic lupus erythematosus (SLE) was measured by growing cells in the presence and in the absence of 6-thioguanine. Patients with SLE had a spectrum of FMC ranging from normal to about 100 times normal. This high FMC among cells from SLE patients appears to reflect excessive in vivo activation and proliferation during the course of the disease. This represents the first demonstration of such a T cell abnormality in SLE; it supports the hypothesis that SLE T cells demonstrate increased in vivo division and/or survival.

In vitro platelet serotonin secretion and inhibition on variously treated root surfaces

Platelet degranulation can result in the release of a variety of factors which are chemotactic, mitogenic, and angiogenic, making platelets extremely important in the regulation of the repair process. This study examines how various types of root surfaces affect platelet deposition and the release of serotonin from dense granules. In addition, experiments were performed to evaluate the effects of the cyclo-oxygenase inhibitor, indomethacin, on platelet deposition and dense granule release. Roots from freshly extracted teeth from sites with periodontal disease (PD) and from healthy sites were sectioned and had the following surface conditions: 1) periodontal ligament present; 2) PD; 3) PD, root planed; 4) PD, root planed and demineralized; and 5) condition 4 treated with collagenase. In addition, rabbit calcaneal tendon collagen was used. All samples were incubated with platelets labeled with both 111Indium and 14C serotonin, with and without the addition of indomethacin. It was observed that the greatest number of platelets deposited on the tendon collagen. Furthermore, serotonin release occurred on all samples except PD and indomethacin partially inhibited platelet deposition on all samples except tendon collagen. Finally, indomethacin inhibited serotonin release on all surfaces. These results suggest that attachment of platelets to the root surface is facilitated by metabolism through the cyclo-oxygenase pathway and that limited platelet deposition can occur in the absence of dense body release.

Quantitation of IgM- and IgG-secreting B cells in the peripheral blood of patients with systemic lupus erythematosus

An enzyme-linked immunospot assay was used to quantitate the number of autoantibody-secreting B cells in the peripheral blood of 67 patients with systemic lupus erythematosus. These patients had 1.5-4-fold more lymphocytes secreting IgG and IgM per million peripheral blood lymphocytes than did normal controls. There was a concomitant increase in the number of B cells secreting antibodies reactive with a diverse panel of foreign and self antigens (including actin, myosin, tri-nitrophenylated keyhole limpet hemocyanin, ovalbumin, and retroviral gp160). By comparison, the number of B cells producing anti-DNA antibodies was increased disproportionately. The magnitude of this anti-DNA response correlated significantly with disease activity. Thus, B cell activation in human systemic lupus erythematosus had characteristics of both generalized (polyclonal) B cell activation and (auto)antigen-specific immune stimulation.

Cytokine gene expression after in vivo primary immunization with goat antibody to mouse IgD antibody

Cytokines are important mediators of effector lymphoid cell function during an immune response, but their expression during an in vivo immune response has not been well documented. We analyzed the kinetics of cytokine gene expression during the course of an in vivo primary immune response to goat antibody to mouse IgD antibody. Total RNA was purified from spleens taken from freshly killed BALB/c mice 1 to 7 days after immunization. The reverse transcriptase polymerase chain reaction was used to evaluate the expression of seven cytokine genes, all of which encode cytokines that are secreted by T cells and are important in T and/or B cell activation and differentiation. These were IFN-gamma, IL-2, IL-4, IL-5, IL-6, IL-9, and IL-10. IL-2 and IL-9 exhibited an early elevated expression at days 2 to 3, and declined as the expression of IL-4, IL-6, IL-10, and IFN-gamma increased. In contrast, IL-5 gene expression showed little change, exhibiting a similar pattern to the housekeeping gene, hypoxanthine-guanine phosphoribosyl transferase. Cell sorting of CD4+ and CD4- cells at day 3 and day 5 after immunization revealed that CD4+ cells were the predominant source of the elevated cytokines (with the exception of IL-6). Our results demonstrate a specific and highly reproducible cytokine gene expression pattern during the course of a primary in vivo immune response that is marked by an absence of a clear-cut Th1/Th2 dichotomy.

Cytokine gene expression after in vivo primary immunization with goat antibody to mouse IgD antibody

Cytokines are important mediators of effector lymphoid cell function during an immune response, but their expression during an in vivo immune response has not been well documented. We analyzed the kinetics of cytokine gene expression during the course of an in vivo primary immune response to goat antibody to mouse IgD antibody. Total RNA was purified from spleens taken from freshly killed BALB/c mice 1 to 7 days after immunization. The reverse transcriptase polymerase chain reaction was used to evaluate the expression of seven cytokine genes, all of which encode cytokines that are secreted by T cells and are important in T and/or B cell activation and differentiation. These were IFN-gamma, IL-2, IL-4, IL-5, IL-6, IL-9, and IL-10. IL-2 and IL-9 exhibited an early elevated expression at days 2 to 3, and declined as the expression of IL-4, IL-6, IL-10, and IFN-gamma increased. In contrast, IL-5 gene expression showed little change, exhibiting a similar pattern to the housekeeping gene, hypoxanthine-guanine phosphoribosyl transferase. Cell sorting of CD4+ and CD4- cells at day 3 and day 5 after immunization revealed that CD4+ cells were the predominant source of the elevated cytokines (with the exception of IL-6). Our results demonstrate a specific and highly reproducible cytokine gene expression pattern during the course of a primary in vivo immune response that is marked by an absence of a clear-cut Th1/Th2 dichotomy.