An IgM lambda antibody to Escherichia coli produces false-positive results in multiple immunometric assays.

BACKGROUND: Interferences in immunometric assays as a result of human anti-immunoglobulin antibodies frequently have been described in the literature. The etiology of these interfering antibodies is usually not known but has been associated with rheumatoid factors in some assays. It is known that microorganisms in experimental settings can induce anti-immunoglobulin antibodies. METHODS: Following Escherichia coli septicemia, a 56-year-old male patient had increased immunoassay results for cardiac troponin I, thyrotropin, human chorionic gonadotropin, alpha-fetoprotein, and CA-125 that were consistent with myocardial infarction, hyperthyroidism, and pregnancy, and suggestive of an occult neoplasm such as hepatic or ovarian cancer. None of these diagnoses were consistent with the rest of his medical exam. In addition, the patient had a restricted IgM lambda paraprotein by immunofixation. Plasma from the patient was incubated with Sepharose-conjugated protein A, irrelevant murine monoclonal antibodies, and formalin-killed E. coli organisms from his infection to determine whether these immunoassay values were falsely increased. RESULTS: Incubation of the patient's plasma with irrelevant murine monoclonal antibodies or the E. coli organism produced normal immunoassay values and removed the IgM lambda paraprotein. CONCLUSIONS: The patient produced a very restricted IgM lambda antibody response to the E. coli infection that had anti-immunoglobulin activity and caused falsely increased values in numerous immunometric assays. Microorganism-induced anti-immunoglobulin antibodies are discussed in the context of this patient.

Effects of systemic resiniferatoxin treatment on substance P mRNA in rat dorsal root ganglia and substance P receptor mRNA in the spinal dorsal horn.

Capsaicin depletes the sensory neuropeptide substance P (SP) in the rat due to a combination of neuron loss and decreased synthesis in the surviving cells. Resiniferatoxin (RTX) mimics most, but not all, capsaicin actions. In the present study, the effects of RTX (300 microg/kg, s.c.) were examined on mRNA levels for SP and its receptor in the adult rat. The percentage of dorsal root ganglia (DRG) neuronal profiles showing an in situ hybridization signal for preprotachykinin mRNAs encoding SP was not altered following RTX treatment (up to 8 weeks), though the signal became perceptibly weaker. In accord, 2 weeks after RTX administration a 60% decrease was observed in the steady-state levels of SP-encoding mRNAs using Northern blot analysis, leaving the ratio of beta- and gamma-preprotachykinin mRNAs unchanged. No change was, however, observed in mRNA levels encoding tachykinins NK-1 receptors in the dorsal horn, the spinal targets for SP. The present findings suggest that RTX does not kill SP-positive DRG neurons, though it suppresses the synthesis of SP. Since RTX treatment does not alter NK-1 receptor expression, this reduced SP synthesis is likely to play a central role in the analgesic actions of RTX.

Effects of the capsaicin analogue resiniferatoxin on spinal nociceptive mechanisms in the rat: behavioral, electrophysiological and in situ hybridization studies.

The effect of a single subcutaneous (s.c.) injection of the ultrapotent capsaicin analogue resiniferatoxin (RTX) on responses of adult rats to noxious thermal and mechanical stimulation was examined. The effects of RTX treatment on the nociceptive flexor reflex and activity-dependent increase in spinal excitability after conditioning C-fiber stimulation (CS) were also assessed. Finally, the expression of galanin message associated peptide (GMAP) mRNA in dorsal root ganglion (DRG) cells and the effects of the high affinity galanin receptor antagonist M35 on the flexor reflex in RTX-treated rats were evaluated. RTX, but not vehicle, produced marked thermal hypoalgesia on the hot plate test with partial recovery in about 50% of animals after about 2 weeks and no recovery in the remaining rats after 4 weeks. In all animals there was only a transient and moderate increase in paw withdrawal threshold to mechanical pressure. The flexor reflex in response to a C-fiber CS train was recorded 15-35 days after RTX or vehicle treatment. There was no difference between RTX and vehicle treated rats on baseline response, but RTX treatment lead to less wind-up during the CS and reduced hyperexcitability. This was particularly the case for rats which did not recover from RTX-induced hypoalgesia. The C-fiber mediated hyperexcitability was potentiated by the galanin receptor antagonist M35, more so in the non-recovered rats than in the partially recovered rats. The number of DRG cells expressing GMAP mRNA was significantly higher in non-recovered than in partially recovered rats. Thus, RTX produced marked and prolonged impairment of capsaicin-sensitive afferents and upregulation of the inhibitory neuropeptides GMAP and galanin in DRG neurons, which may underlie the prolonged effect of RTX.

Vanilloid receptor loss is independent of the messenger plasticity that follows systemic resiniferatoxin administration.

Resiniferatoxin (RTX) depletes vanilloid (capsaicin) receptors from lumbar dorsal root ganglia (DRG) of the rat. In addition, RTX causes changes in neuropeptide and nitric oxide synthase expression in lumbar DRG neurons, similar to those described following axotomy; this latter phenomenon is referred to as messenger plasticity. These findings suggested that vanilloid receptor loss may be part of the plasticity that follows RTX treatment. Here we show that vanilloid receptor expression, as detected by [3H]RTX autoradiography, is not changed in lumbar DRGs of axotomized rats, nor is it altered in a rat model (chronic constriction injury) of neuropathic pain. Thus, the in vivo expression of vanilloid receptors detected by specific [3H]RTX binding does not require the presence of intraaxonally transported trophic factors such as nerve growth factor. We conclude that messenger plasticity and vanilloid receptor loss are mediated by distinct mechanisms.

Vanilloid (capsaicin) receptors in the rat: distribution in the brain, regional differences in the spinal cord, axonal transport to the periphery, and depletion by systemic vanilloid treatment.

Vanilloid (capsaicin) receptors were visualized by [3H]resiniferatoxin (RTX) autoradiography in the brain of newborn as well as adult (both control and colchicine-treated) rats. Specific labelling was seen in the brain stem only, in the nucleus of the solitary tract extending into the area postrema and the spinal sensory nucleus of the trigeminal nerve. Also, a strong signal was seen in the dorsal horn, dorsal root, trigeminal and nodose ganglia. Membranes obtained from the cervical, thoracic, and lumbar segments of the spinal cord showed similar affinities for RTX and likewise for capsaicin and capsazepine; maximal receptor density was similar in the cervical and thoracic segments (approximately 70 fmol/mg protein) but was twice as high in the lumbar segment. 24 h after ligation of the vagal or the sciatic nerves, a strong accumulation of specific RTX binding sites was observed mainly proximal to the ligature, implying intraaxonal receptor transport from the nodose and dorsal root ganglia, respectively, to the periphery. Systemic (s.c.) vanilloid treatment depleted specific [3H]RTX binding sites from the brain stem, the sensory (dorsal root as well as trigeminal) ganglia, and the spinal cord. RTX was approximately 200-fold more potent than capsaicin for eliminating vanilloid receptors from the spinal cord. The present results suggest a discrete expression of vanilloid receptors in the brain stem (sensory nuclei); although intrinsic vanilloid receptor-expressing neurons are though to exist in the rat brain, they remain undetected by the present [3H]RTX autoradiography methodology.

Increased levels of GMAP, VIP and nitric oxide synthase, and their mRNAs, in lumbar dorsal root ganglia of the rat following systemic resiniferatoxin treatment.

Using in situ hybridization, the expression of mRNA encoding galanin, vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), and nitric oxide synthase (NOS), respectively, was studied in lumbar dorsal root ganglia of rats given a single s.c. dose of 300 micrograms kg-1 resiniferatoxin (RTX), an ultrapotent capsaicin analogue. In control animals, 10% of the DRG neurones were positive for galanin mRNA, whereas no message for VIP, NPY or NOS could be detected. One week after RTX treatment, a markedly increased number (approximately 30%) of the neurones expressed galanin mRNA. Simultaneously, VIP and NOS mRNA became detectable in 6-8% of the neurones. The number of galanin-positive neurones declined after 2 weeks and returned to control levels by 8 weeks. The increase in number of VIP-, or NOS-positive neurones persisted up to 4 weeks after RTX treatment and declined thereafter. Also, there was a small increase in NPY mRNA-positive neurones. In parallel immunohistochemical experiments, similar increases were observed for galanin message-associated protein (GMAP)-, VIP- and NOS-like immunoreactivities. Our findings suggest that RTX can cause changes (messenger plasticity) in galanin, VIP and NOS expression in capsaicin-sensitive sensory neurones of the rat, similar to those described following axotomy.

High nitric oxide production in human paranasal sinuses.

Nitric oxide (NO) is present in air derived from the nasal airways. However, the precise origin and physiological role of airway-derived NO are unknown. We report that NO in humans is produced by epithelial cells in the paranasal sinuses and is present in sinus air in very high concentrations, close to the highest permissible atmospheric pollution levels. In immunohistochemical and mRNA in situ hybridization studies we show that an NO synthase most closely resembling the inducible isoform is constitutively expressed apically in sinus epithelium. In contrast, only weak NO synthase activity was found in the epithelium of the nasal cavity. Our findings, together with the well-known bacteriostatic effects of NO, suggest a role for NO in the maintenance of sterility in the human paranasal sinuses.

Diabetic glomerulopathy in the SHR/N-corpulent rat: role of dietary carbohydrate in a model of NIDDM.

We evaluated the course of diabetes and nephropathy in the SHR/N-cp (corpulent) rat characterized by genetic obesity, non-insulin-dependent diabetes (NIDDM), and hypertension, and examined whether the nephropathy in this model is influenced by the type of carbohydrate intake. Two groups of obese and lean SHR/N-cp rats were fed diets containing 54% carbohydrate, as either sucrose or starch for 3 months (group I) and 9 months (group II). After 3 months on either diet, group I obese rats had higher 2-h response serum glucose levels and urinary glucose excretion than lean rats. Sucrose feeding was associated with greater proteinuria and a higher percentage of abnormal glomeruli in obese rats. Morphometric evaluation of glomeruli (by computerized image analysis) showed greater mean renal corpuscular volume and mesangial fraction in obese than in lean rats fed similar diets. Mean renal corpuscular volume and mesangial fraction were also greater in sucrose-fed obese rats than in starch-fed obese rats. After 9 months, group II obese rats had substantial reductions in serum and urine glucose levels but they were still hyperinsulinaemic and showed more proteinuria than lean rats and a higher percentage of sclerotic glomeruli compared with group I obese rats. At this time, mean mesangial fraction but not renal corpuscular volume was still higher in obese than in lean rats.(ABSTRACT TRUNCATED AT 250 WORDS)

HIV-associated immune-mediated renal disease.

Although focal glomerulosclerosis is the most common renal disease, other proliferative glomerulonephritides are encountered in HIV-infected patients. We studied four HIV-infected patients with renal insufficiency, proteinuria, and proliferative glomerulonephritis, consistent with immune-mediated disease, to investigate the role of the virus and immune complexes in the pathogenesis of the nephropathy. Circulating immune complexes (CICs) and HIV-reactive antibodies were measured and characterized in each patient. Renal biopsy tissue was acid eluted, and the eluate analyzed. DNA extracted from biopsies was subjected to the polymerase chain reaction (PCR) to detect HIV genome. CICs were detected in each patient: an IgA-p24 HIV antigen complex and an IgG antibody-gp 120 HIV antigen complex in two patients; two patients had an IgG-p24 HIV antigen complex. Identical complexes were eluted from renal tissue in the first three patients; p24 HIV antigen, and complement from the fourth. The eluted antibodies reacted with the HIV antigens from the isolated CICs. Direct immunofluorescence for viral antigen in the eluted glomerular tissue revealed HIV antigens; PCR confirmed the presence of gag genome in all four biopsies. We conclude both circulating and in-situ HIV antigen-specific immune complexes may be associated with glomerulonephritis in HIV infected patients. Viral incorporation into renal tissue may be important in the pathogenesis of HIV-associated renal disease.

Viral DNA in microdissected renal biopsy tissue from HIV infected patients with nephrotic syndrome.

Focal glomerulosclerosis (FGS) has been considered as HIV-associated nephropathy, a specific renal complication of infection. To determine whether renal disease in HIV infected patients has one highly prevalent pathologic expression, and whether renal parenchymal viral genomic incorporation affects pathologic outcome, we reviewed renal biopsies performed at our center. Twenty-eight HIV infected patients with nephrotic range proteinuria underwent renal biopsy for diagnosis of renal disease: 85.7% led homosexual or bisexual lifestyles; 10.7% admitted to intravenous drug use; and 85.7% were Black. Only 53.6% had FGS; 28.6% had glomerulonephritis. Two patients had diabetic renal disease; 93.3% of patients with FGS and 87.5% of patients with glomerulonephritis were Black. Paraffin slides of twenty-two of the patients' renal biopsies were evaluated by polymerase chain reaction (PCR) for the presence of HIV DNA, using primers and probes to the gag gene, detected by liquid hybridization and polyacrylamide gel electrophoresis. Twenty-one of the twenty-two evaluated tissue specimens showed the presence of HIV DNA. Microdissection studies of glomeruli, tubules, interstitial cells and infiltrating inflammatory cells showed the presence of HIV genome in all but interstitial cells. HIV infected patients without renal disease also had positive PCR evaluations of microdissected tissue, while non-infected patients were all negative. We conclude that although focal glomerulosclerosis is the most common renal pathologic lesion in patients with HIV infection and nephrotic range proteinuria, glomerulonephritis is a relatively frequent finding. HIV genome is present in renal tissue in HIV infected subjects with nephrotic range proteinuria, but is also found in HIV infected subjects without nephropathy.(ABSTRACT TRUNCATED AT 250 WORDS)