Anti-beta2 glycoprotein I and anticardiolipin antibodies in leptospirosis, syphilis and Kala-azar

OBJECTIVE

Reports have shown that anticardiolipin (aCL) antibodies present in patients with autoimmune diseases are dependent on the cofactor,beta2 glycoprotein I (beta2 GPI), as opposed to aCL antibodies seen in infectious diseases such as syphilis, HIV hepatitis C, etc. The assay for anti-beta2GPI antibodies has been reported to be more specific for antiphospholipid syndrome (APS). However, the prevalence of these antibodies in diseases such as leishmaniasis and leptospirosis remains unknown. The aim of the present study was determine the prevalence of antibodies to cardiolipin and to beta2GPI in patients with different infectious diseases, including leptospirosis, syphilis and leishmaniasis.

METHODS

Samples from patients with Kala-azar (visceral leishmaniasis), syphilis or leptospirosis were tested for IgG and IgM anticardiolipin and IgG anti-beta2GPI antibodies by ELISA.

RESULTS

In patients with Kala-azar the prevalence of IgG aCL, IgM aCL and anti-beta2GPI was 6% (2/30), 3% (1/30) and 53% (16/30), respectively. In syphilis the prevalence was 18% (14/74), 13% (10/74) and 10% (8/70), respectively. In leptospirosis the frequency of these antibodies was 23% (9/39), 10% (4/39) and 17% (6/34), respectively. There was no statistical correlation between aCL and anti-beta2GPI antibodies in these diseases.

DISCUSSION

This study clearly shows a significant prevalence of anti-beta2GPI antibodies in leptospirosis and leishmaniasis and syphilis. This indicates that the assay for antibeta2GPI antibodies should be thoroughly validated before it is introduced as a definitive tool for the diagnosis of APS, testing a larger number of sera from patients with a wider range of clinical conditions.

A study of high-index-contrast 90 degree waveguide bend structures

We present an evaluation of the parameters involved in designing low-loss right-angle waveguide bends based on a high index contrast materials system. We apply the finite difference time domain method (FDTD) to several two-dimensional bend structures and study the effects of varying the bend geometry. Such a study is relevant for the understanding of bend mechanisms and for the optimization and fabrication of high-density high-contrast integrated optical components. The study indicates that high bend transmission can be achieved with the addition of a low- Q resonant cavity; however, similar or even better performance can be achieved with a structure that combines a corner mirror with a phase retarder. The use of a double corner mirror structure is shown to further increase the bend transmission, with little increase in bend area.

Identification of an Fc gamma receptor-independent mechanism by which intravenous immunoglobulin ameliorates antiphospholipid antibody-induced thrombogenic phenotype

OBJECTIVE

Patients with the antiphospholipid antibody syndrome (APS) often experience recurrent arterial and venous thrombosis and pregnancy losses. Intravenous immunoglobulin (IVIG) therapy has prevented pregnancy loss in some women with APS and has reversed fetal resorption rates in murine models of pregnancy loss. Although the basis for these effects is unknown, effector mechanisms of pathogenic antibodies often involve receptors for IgG (Fc gamma receptors [Fc gammaR]). We examined the potential mechanisms of action of WIG in an in vivo murine model of antiphospholipid antibody (aPL)-induced thrombosis and endothelial cell activation.

METHODS

Mice infused with IgG containing human anticardiolipin antibodies (aCL) were treated with IVIG (36 microg i.v.), saline, or ovalbumin. Surgically induced thrombus formation and in vivo leukocyte adhesion to endothelial cells were measured. Circulating levels of aCL were measured by enzyme-linked immunosorbent assay. To determine whether Fc gammaR are required for the effects of IVIG, we treated mice deficient in stimulatory Fc gammaR. To examine the effects of IVIG on endogenously generated antibody, we treated mice immunized with beta2-glycoprotein I (beta2GPI).

RESULTS

IVIG treatment inhibited aPL-induced endothelial cell activation and enhancement of thrombosis in mice passively infused with human aPL-containing IgG, and this was associated with a decrease in aPL levels. Similarly, IVIG lowered aPL levels and inhibited thrombogenesis in mice immunized with beta2GPI. The thrombophilic effects of aPL were evident in Fc gammaR-deficient mice.

CONCLUSION

Treatment with IVIG inhibits the thrombogenic effects of aPL in vivo and reduces the levels of aCL in the circulation. Blockade of stimulatory Fc gammaR on inflammatory cells is not necessary for this effect. The mechanism of action of IVIG is more likely saturation of the IgG transport receptor, leading to accelerated catabolism of pathogenic aPL. These results have implications in the management of thrombosis in APS and may have applications for pregnant patients with a history of APS.

Functional analyses of patient-derived IgG monoclonal anticardiolipin antibodies using in vivo thrombosis and in vivo microcirculation models

Antiphospholipid antibodies (aPL) have been associated with thrombosis and pregnancy losses in patients diagnosed with antiphospholipid syndrome (APS) and enhance thrombus formation in vivo in mice, but the mechanism of thrombosis by aPL is not completely understood. It has been proposed that aPL may affect endothelial cell (EC) function and/or induce their activation, transforming their anticoagulant surface into procoagulant, thus predisposing to thrombosis. It has been proposed that aPL may affect EC cell function and/or induce their activation, transforming their anticoagulant surface into procoagulant, thus predisposing to thrombosis. This study proposes to test the hypotheses that some IgG anticardiolipins (IgG aCL) with thrombogenic properties in mice, exert their effects through activation of endothelium. We studied seven patient-derived monoclonal aCL for their thrombogenic properties in an in vivo pinch-induced thrombosis model, and their functional activities in activating EC by analyzing in vivo leukocyte adhesion to endothelium in microcirculation in venules in exposed murine cremaster muscle and in vitro adhesion molecule expression in cultured EC. The binding of the monoclonal aCL to EC was also tested. In addition to the previous identified thrombogenic IS2, four of the five new more IgG monoclonal aCL (from two patients) were found to be thrombogenic. Of these five thrombogenic aCL, three caused more in vivo leukocyte adhesion to EC in microcirculation, as compared to that induced by the H2 control human monoclonal IgG, and enhanced expression of adhesion molecules (particularly VCAM-1) on cultured EC. These data show that about 2/3 patient-derived IgG monoclonal aCL are thrombogenic and suggest that some thrombogenic IgG aCL exert their effects through activating EC.

[Treatment of idiopathic thrombocytopenic purpura with danazol]

PURPOSE

To assess the response to danazol in our patient population with ITP.

PATIENTS AND METHODS

We evaluated 17 patients with ITP (11 women and 6 men) with average age 67.3 +/- 9.9 years (range 46-83): 10 patients with acute ITP without response to corticosteroids during 4-6 weeks; 4 patients with acute ITP without treatment; 2 patients with chronic ITP and 1 patient with recurrent ITP resistant to corticosteroids. The dose of danazol ranged between 100 and 600 mg/d. The patients were included in two groups: 1) Responders if they achieved complete or partial remission; 2) Non-responders if they achieved transient or fair response.

RESULTS

The overall response rate was 58.8% and in patients previously treated 46.1%. The time to response was 35.6 +/- 48.5 days (range 14-180 days). Among the 10 responder patients 6 have remained in remission, 1 died 6 months after the remission for unrelated disease, and 3 relapsed after discontinuation of treatment with a good response after the reinstitution of therapy. Two patients resistant to treatment with danazol were splenectomized with transient response, and they responded favorably to the reinstitution of danazol. The treatment had a good tolerance.

CONCLUSION

1) The treatment with danazol in ITP is a good alternative therapeutical approach as initial treatment in ITP and ITP patients without response to corticosteroids. 2) ITP patients resistant to danazol may response to this treatment after splenectomy.

[Idiopathic myelofibrosis with extramedullary hematopoiesis foci in the skin and testicles. Report of a case]

Idiopathic myelofibrosis (IMF) is a clonal chronic myeloproliferative syndrome characterized by the proliferation of the three haemopoietic series and the marrow connective tissue and by the development of extramedullary haemopoiesis in the liver, spleen and lymph nodes. Cutaneous extramedullary haemopoiesis is an uncommon event and we could not find any reported cases of testicular involvement in this disease. We report the case of a 28 year-old male with diagnosis of idiopathic myelofibrosis in November 1988. During the course of the disease, three years later, he developed a tumor on his right testis. Histologic examination showed extramedullary haemopoiesis with cells of the myeloid, erythroid and megakaryocyte series, in the interstice. Eight months later, numerous red-purple papules and nodules developed on the patients's trunk. The biopsy of a skin lesion revealed an infiltration of the dermis by myeloid, erythroid cells and few megakaryocytes. The patient's clinical condition worsened, and he died in February 1993 following progressive deterioration of the general condition. We describe a case of IFM with extramedullary hemopoiesis involving the skin and the testis pointing out the rarity of these localization.

A 13-mer peptide straddling the leucine33/proline33 polymorphism in glycoprotein IIIa does not define the PLA1 epitope

We confirm the recent report (J Clin Invest 83:1778, 1989) of a polymorphism at amino acid 33 of platelet GPIIIa associated with the PLA1/PLA2 phenotype by using the polymerase chain reaction on cDNA derived from platelet RNA, using the base-pair primers 105-129 and 452-428. Platelet cDNA from three PLA2-homozygous individuals, when digested with Nci I, gave two bands of 256 bp and 91 bp, whereas eight PLA1 cDNAs gave a single band of 347 bp. Two 13-mer amino acid peptides straddling the amino acid polymorphism: SDEALP (L/P) GSPRCD were synthesized for epitope studies. Two mouse polyclonal antibodies were raised: one against the PLA1-associated peptide, the other against the PLA2 peptide. Both antibodies react with either peptide, as well as with both PLA1 and PLA2 platelets. The PLA1 peptide did not block the binding of two different human anti-PLA1 antibodies to the 100-Kd GPIIIa band on immunoblot of platelet extracts; neither did it block the binding of the same antibodies to PLA1-platelet extracts in an enzyme-linked immunosorbent assay. Further studies were performed on the PLA1 epitope following subtilisin digestion of purified GPIIIa. A 55-Kd fragment was obtained that retained the PLA1 epitope as well as the first 13 N-terminal amino acids of GPIIIa. Reduction of the 55-Kd fragment resulted in loss of the PLA1 epitope with production of a 67-Kd, 21-Kd, and 10-Kd band on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The 55-Kd band does not react with LK-2, a monoclonal antibody versus GPIIIa that inhibits adenosine diphosphate, collagen, epinephrine, and thrombin-induced aggregation. Thus, the PLA1 epitope is conformation-induced, resides on an N-terminal 55-Kd fragment composed of two or more peptides held together by -SH bonds, and is not required for platelet aggregation.