Biocompatibility evaluation of polyamide hemofiltration.

INTRODUCTION: Postdilution hemofiltration with a polyamide membrane is a renal replacement technique widely used, but very little information is available regarding the biocompatibility of this treatment. In this paper we report the results of an acute study of the biocompatibility of polyamide hemofiltration. PATIENTS AND METHODS: Complement activation such as C3a and C5a Des Arg (RIA), granulocyte degranulation like alpha 1 elastase intradialytic increase (ELISA) and the expression of high affinity membrane receptors for IL-2 (anti-TAC) were determined. Beta 2-microglobulin (RIA) intradialytic decrease, as well as its convective removal, was evaluated. The nature of protein layer adsorbed onto the polyamide membrane, at the end of the dialytic session was investigated with a new immunohistochemical technique. Cell-associated cytokine concentration (like IL-1 beta and IL-1Ra - ELISA) was determined on mononuclear cell lysates. RESULTS: A low degree of complement activation was detected with the polyamide membrane when data were adjusted for hemoconcentration and for 1 m2 of membrane surface area. An important convective removal not only of Beta 2-microglobulin (258+/-20 mg/session), but also of the activated anaphylatoxins (225+/-76 ng/ml for C3a and 22.5+/-4 ng/ml for C5a) was revealed. A marked deposition of all coagulation factors with no detectable amount of immunoglobulins and complement factors was revealed on the polyamide membrane at the end of the dialytic session. No intradialytic (for IL-1beta) (from 14. 1+/-3.0 to 13.5+/-2.9 pg/2.5 x 10(6) cell) and interdialytic (for IL-1Ra) (from 4572+/-1076 to 5408+/-615 pg/2.5 x 10(6) cell) cell-associated cytokine expression was induced by hemofiltration. DISCUSSION AND CONCLUSION: Polyamide hemofiltration is a highly biocompatible technique due to the use of a synthetic membrane with a sterile reinfusion fluid and the convective removal of the activated anaphylatoxins and Beta 2-microglobulin.

IgG, IgA and C3 deposits in the extra-thyroidal manifestations of autoimmune Graves' disease: their in vitro solubilization by intravenous immunoglobulin.

OBJECTIVE: To study the involvement of antibodies in the extrathyroidal manifestations of autoimmune Graves' disease, we determined the presence of IgG, IgA and IgM antibodies and C3c in connective tissue samples from patients with Graves' disease and pretibial myxedema (PTM) or thyroid associated ophthalmopathy (TAO). METHODS: Connective orbital tissue samples were obtained from 12 patients undergoing orbital decompression for TAO, and skin samples from lesions on the pretibial area were obtained in 7 patients with PTM. Sections from each tissue sample were stained with fluorescin-isothiocianate conjugated anti-human IgG, IgA, IgM and C3c and were examined by a fluorescence optical instrument. Other serial sections from each sample were incubated with human IgG solutions (concentration 6 mg/ml or 20 mg/ml), human albumin (40 mg/ml), PBS, myoglobin (40 mg/ml), or IgA (20 mg/ml), and were then processed by a standard direct immunofluorescence staining procedure. RESULTS: Among the samples from TAO patients 8/12 (67%) were positive for IgG deposition, 4/9 (44%) were positive for IgA, 1/9 (11%) was positive for IgM and 4/9 (44%) were positive for C3c deposition. Orbital connective samples from 3 non-TAO patients were all negative. Among samples from PTM patients 4/7 (57%) were positive for IgG deposition, 3/ 4 (75%) were positive for IgA, 0/4 was positive for IgM and 3/7 (43%) were positive for C3c deposition. Skin samples from 5 control patients undergoing skin biopsy for non-autoimmune diseases were all negative. Incubation with human IgG (20 mg/ml) resulted in the complete disappearance of IgG and C3c deposition in all positive patients. No significant variation in IgG fluorescent staining after incubation with either 6 mg/ml of IgG solution, human albumin, PBS, myoglobin or IgA was observed. CONCLUSION: The results of our study suggest that different classes of antibodies, mainly IgG and IgA, may be implicated in the disease process in autoimmune TAO and PTM. Activation of the complement cascade, via the classic or the alternative pathway, could take place in about 40% of these patients. IVIG in vitro may solubilize, by a specific mechanism, IgG and complement immune complex deposition in the extrathyroidal manifestations of autoimmune Grave's disease.

Ocular larva migrans and histopathological lesions in mice experimentally infected with Baylisascaris transfuga embryonated eggs.

The ability of Baylisascaris transfuga larvae to cause ocular larva migrans (OLM) in mice was examined. Mice were given approximately 3500 infective eggs of B. transfuga per os. Their eyes were removed and examined either microscopically or histologically at various intervals post-infection. Larvae were recovered beginning 7 days after infection. Histologically, free larvae were observed in the posterior chamber and within the ocular membranes. Larval granulomas were present in the choroid with involvement of retinal layers. It was concluded that B. transfuga larvae have the ability to produce OLM in mice following oral infection and should be considered as possible agents of OLM in other animals and in human beings.

Acute suppression of parathyroid activity during hemofiltration.

Hemofiltration (HF) induces a significant reduction in parathormone (PTH). This effect is related not only to the convective removal of PTH molecules but also to the biological suppression of parathyroid glands by plasma-ionized calcium (iCa) increase. The acute inhibitory effect on parathyroid gland activity, ionized calcium mass balance, phosphate kinetics and intact PTH (PTHi) dialytic removal during post-dilution polyamide HF were studied in 31 chronic uremic patients. HF ensures good phosphate removal (from 2.54 +/- 1.19 to 1.27 +/- 0.35 mEq/l; p < 0.01), a positive iCa mass balance (8 +/- 4 mmol/session) with a iCa plasma increase and negligible convective PTHi removal (9 +/- 2 pg/ml). Study of the PTHi profile during HF characterized two different parathyroid responses: 26/31 patients showed a physiological parathyroid gland response to the iCa increase (from 1.17 +/- 0.09 to 1.42 +/- 0.07 mmol/l; p = 0.002) with a significant PTHi decrease (from 123 +/- 111 to 35 +/- 28 pg/ml; p = 0.01) and a maximal PTH inhibition of 88%. In 5 patients, with more severe hyperparathyroidism, in spite of a comparable increase in iCa (from 1.28 +/- 0.12 to 1.46 +/- 0.08 mmol/l; p = 0.02), this physiological calcium-PTHi feedback was lost, revealing an autonomization of the gland (maximal inhibition of 45%). In our experience, study of the PTHi profile during a single HF session may represent a clinical test for the functional exploration of parathyroid glands, suggesting future (medical or surgical) clinical strategy.

Protein layer on hemodialysis membranes: a new immunohistochemistry technique.

In order to investigate the nature of the protein layer deposited on hemodialysis membranes we developed a direct immunohistochemical technique using fluoresceinated antibodies to plasma membranes. Fifteen patients on regular dialytic treatment were dialyzed with CU, HE, PAN, PS and PMMA and the dialyzers analyzed at the end of a standard dialytic session. Snap frozen sections of hollow fiber devices were treated with flourescein-isothiocyante conjugated antibodies for IgG, IgA, IgM C3c, fibrinogen, factor VIII, factor XIIIa-s, antithrombin III, fibrinogen degradation products (PDF) and plasminogen. Protein deposits were evaluated by a quantitative criteria, which evaluates the intensity of fluorescence and the area of the capillary wall occupied by this fluorescence by using an image analysis software. The coagulation cascade is activated by all membranes and similar deposits of these proteins were revealed, whereas important differences in C3c deposition were found.

Parenteral infection in mice with Baylisascaris transfuga (Nematoda: Ascaridae) infective eggs.

In order to investigate the ability of infective larvae of the nematode Baylisascaris transfuga (Rudolphi, 1819) Sprent, 1968 to hatch from the egg-shells and then to migrate in tissues, parenteral infections of mice with embryonated eggs were performed. Two groups of outbred albino mice were infected with approximately 3500 B. transfuga infective eggs subcutaneously (s.c.) or intraperitoneally (i.p.). B. transfuga larvae in the i.p. group rapidly hatched and migrated to the intestine, liver, lungs, brain and carcass. Subcutaneous inoculation of eggs was followed also by migration of hatched larvae in the examined organs. In the s.c. mice, extensive encapsulating reactions involving the subcutaneous tissues and carcass, and containing large numbers of hatched eggs and free motile larvae, were found at the sites of inoculation. Some differences in the migratory behaviour were observed between the two groups. It is shown that B. transfuga infective larvae are able to hatch and migrate in tissues of mice, and tend to settle and/or to be trapped in the intestinal wall and muscles, even after parenteral inoculations of embryonated eggs. These results could provide basic data for further investigations on the migratory pathways of B. transfuga larvae or to perform immunological and therapeutical studies.

Visceral larva migrans in mice experimentally infected with Baylisascaris transfuga (Ascarididae: Nematoda).

Laboratory bred albino mice, weighing 20 to 25 g, were orally infected with 2000 Baylisascaris transfuga infective eggs each. Mice were randomly chosen and sacrificed on days 1, 2, 3, 10, 15, 24 and 70 post-infection. Samples of intestine, mesenteric lymph nodes, liver, lungs, heart, spleen, kidneys, uterus, brain and skeletal muscles were collected and processed for conventional histopathology. In the early infection the major necropsy findings were focal haemorrhages on the intestinal wall, liver, lungs and brain. Histologically, larvae were found in haemorrhagic areas. In the subacute-chronic infection white nodules were scattered through all the examined organs, except the brain. Histologically, the white nodules corresponded to granulomas containing larvae surrounded by lymphocytes, eosinophil leukocytes and macrophages. The migration of B. transfuga larvae in spleen, kidneys and uterus of infected mice appears to have not been reported by previous workers. The possible role of B. transfuga larvae in the Visceral Larva Migrans syndrome is discussed.

Observations on the infectivity of Baylisascaris transfuga eggs for mice.

To investigate the potential pathogenicity of Baylisascaris spp. nematodes, mice were experimentally infected with Baylisascaris transfuga eggs, which had been cultured in 0.1 N sulphuric acid, for a period in excess of 1 year. Infectivity for mice appeared after 2 weeks in cultures (2.8%), peaked after 4 weeks (37.4%) and then waned over the next 18 months. The implications of B. transfuga as a possible agent of visceral larva migrans in animals and humans was demonstrated.

Experimental infection in chickens with larvae of Baylisascaris transfuga (Nematoda: Ascaridoidea).

The larvae of Baylisascaris transfuga (Rudolphi, 1819) were able to penetrate the liver, lungs, carcass and brain of infected chickens, but a great number of larvae accumulated in the liver. No clinical signs were seen. Birds may serve as paratenic hosts of the parasite, but B. transfuga seems not to be a possible agent of avian cerebrospinal nematodosis.

Renal involvement in mice experimentally infected with Toxocara canis embryonated eggs.

Histological examination of kidneys from mice experimentally infected with Toxocara canis embryonated eggs demonstrated the presence of a segmental or diffuse mesangioproliferative glomerulonephritis. Immunohistochemical studies established that renal alterations were associated with glomerular deposits of IgG, IgM and third component of complement (C3). These findings suggest that an immunomediated mechanism might possibly be involved in the genesis of kidney damage observed in mice infected with T. canis embryonated eggs.

Circulating thymic hormone activity in young cancer patients.

We measured serum levels of Facteur Thymique Sérique (FTS) in 56 young cancer patients compared to normal controls. All patients who received immunosuppressive therapy had low age-corrected titres of FTS. Low levels were also found at diagnosis and off therapy. Plasma from 22 patients contained factors capable of inhibiting biological activity of FTS in vitro. The nature of this inhibitor has not been elucidated. No zinc deficiency was found in the patients studied, suggesting that FTS is secreted in its active form. Our study points out the importance of monitoring FTS activity in young cancer patients for its implications on immunological surveillance. The practical applications of thymic hormone therapy in cancer patients are discussed.