Common epitope on HIV p24 and human platelets

Expression and prognostic value of C-reactive protein in adult immune thrombocytopenia (ITP) patients

The aim of this study was to investigate the effect of C-reactive protein (CRP) on the prognosis of adult patients with Immune thrombocytopenia purpura (ITP). A retrospective study of 628 adult ITP patients, as well as 100 healthy and 100 infected patients, attending the Affiliated Hospital of Xuzhou Medical University from January 2017 to June 2022 was performed. The ITP patients were grouped according to their CRP levels, and the differences in clinical characteristics of each group and the influencing factors of efficacy in newly diagnosed ITP patients were analyzed. CRP levels were significantly higher in the ITP and infected groups compared with healthy controls (P < 0.001), and platelet counts were significantly lower in the ITP group (P < 0.001). Between the CRP normal and elevated group, their age, white blood cell count, neutrophil count, lymphocyte count, red blood cell count, hemoglobin, platelet count, complement C3 and C4, PAIgG, bleeding score, proportion of severe ITP, and proportion of refractory ITP were significantly different (P < 0.05). Patients of severe ITP (P < 0.001), refractory ITP (P = 0.002), and with active bleeding (P < 0.001) had significantly higher CRP levels. Patients with no response after treatment had significantly higher CRP levels than those who achieved CR or R (P < 0.001). Platelet counts (r = - 0.261, P < 0.001) in newly diagnosed ITP patients and treatment outcomes (r = - 0.221, P < 0.001) were negatively correlated with CRP levels, and bleeding score was positively correlated with CRP levels (r = 0.207, P < 0.001). Treatment outcome was positively correlated with decrease in CRP levels (r = 0.313, P = 0.027). A multifactorial regression analysis of the influencing factors of treatment outcomes on newly diagnosed patients found that CRP was an independent risk factor of the prognosis (P = 0.011). In conclusion, CRP can help assess the severity and predict the prognosis of ITP patients.

Emerging Concepts in Immune Thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune disease defined by low platelet counts which presents with an increased bleeding risk. Several genetic risk factors (e.g., polymorphisms in immunity-related genes) predispose to ITP. Autoantibodies and cytotoxic CD8⁺ T cells (Tc) mediate the anti-platelet response leading to thrombocytopenia. Both effector arms enhance platelet clearance through phagocytosis by splenic macrophages or dendritic cells and by induction of apoptosis. Meanwhile, platelet production is inhibited by CD8⁺ Tc targeting megakaryocytes in the bone marrow. CD4⁺ T helper cells are important for B cell differentiation into autoantibody secreting plasma cells. Regulatory Tc are essential to secure immune tolerance, and reduced levels have been implicated in the development of ITP. Both Fcγ-receptor-dependent and -independent pathways are involved in the etiology of ITP. In this review, we present a simplified model for the pathogenesis of ITP, in which exposure of platelet surface antigens and a loss of tolerance are required for development of chronic anti-platelet responses. We also suggest that infections may comprise an important trigger for the development of auto-immunity against platelets in ITP. Post-translational modification of autoantigens has been firmly implicated in the development of autoimmune disorders like rheumatoid arthritis and type 1 diabetes. Based on these findings, we propose that post-translational modifications of platelet antigens may also contribute to the pathogenesis of ITP.

Effects of human immunodeficiency virus on the erythrocyte and megakaryocyte lineages

Anaemia and thrombocytopenia are haematological disorders that can be detected in many human immunodeficiency virus (HIV)-positive patients during the development of HIV infection. The progressive decline of erythrocytes and platelets plays an important role both in HIV disease progression and in the clinical and therapeutic management of HIV-positive patients. HIV-dependent impairment of the megakaryocyte and erythrocyte lineages is multifactorial and particularly affects survival, proliferation and differentiation of bone marrow (BM) CD34+ haematopoietic progenitor cells, the activity of BM stromal cells and the regulation of cytokine networks. In this review, we analyse the major HIV-related mechanisms that are involved in the genesis and development of the anaemia and thrombocytopenia observed in HIV positive patients.

Resolution of autoimmune thrombocytopenia associated with raltegravir use in an HIV-positive patient

About 10% of the human immunodeficiency virus (HIV) patients show thrombocytopenia. We describe the case of an HIV/HCV-positive patient whose autoimmune thrombocytopenia resolved with the addition of raltegravir to previous highly active antiretroviral therapy (HAART). It is noteworthy that the effect on platelet count appeared to be independent of viral load suppression, which was achieved with previous antiretroviral regimens. In fact, it has been suggested that the positive effect exerted by raltegravir on autoimmune diseases is due to its inhibition on herpes viruses, and hence on activation of endogenous human retroviruses. This consideration, if confirmed, could open new avenues in the treatment of autoimmune thrombocytopenia in the HIV setting.

Platelet Count Response to Helicobacter pylori Eradication in Iranian Patients with Idiopathic Thrombocytopenic Purpura

Idiopathic thrombocytopenic purpura (ITP) is an autoimmune hematological disorder characterized by auto antibody-mediated platelet destruction. Although the main cause of ITP remains unclear, but its relationship with some infection was demonstrated. In recent years, many studies have demonstrated improvement of platelet counts in ITP patients after treating Helicobacter pylori infection. The aim of this study was to investigate the effects of H. pylori eradication on platelet count response in Iranian ITP patients.

A total of 26 patients diagnosed with both ITP and H. pylori infection. ITP were diagnosed whose platelet counts were less than 100×10³/μL. These patients were tested for H. pylori infection by Urea Breath Test and serum H. pylori antibody. All patients received triple therapy for 7 or 14 days to eradicate H. pylori infection. These patients followed for six months.

Prevalence of H. pylori was 67.3%. H. pylori eradication achieved in 89.5% (26/29). Of the 26 patients, 15 (57.7%) exhibited a complete response (CR) and 11 (42.3%) were unresponsive. We did not find partial responders. There was a significant difference in the baseline platelet count of responders and non-responders patients (p<0.001). All responders had platelet count ≥50×10³/μL and all non-responders had platelet count <50×10³/μL.

Results of this study revealed that eradication therapy of H. pylori infection can improve platelet counts in ITP patients especially with mild thrombocytopenia and support routine detection and treatment of H. pylori infection in ITP patients in populations with a high prevalence of this infection.

HIV and SIV Associated Thrombocytopenia: An Expanding Role for Platelets in the Pathogenesis of HIV

Thrombocytopenia is common in HIV and SIV infection, and is often associated with disease progression. HIV and SIV-associated thrombocytopenia arise through multiple mechanisms, including decreased platelet production, increased platelet destruction due to HIV-mimetic anti-platelet antibodies, and increased use of activated platelets. Activated platelets have the potential to contribute to the pathogenesis of HIV and SIV by interacting directly with inflammatory cells and endothelium and by releasing soluble immunomodulatory cytokines.

Infectious causes of chronic immune thrombocytopenia

Persistent thrombocytopenia may be the consequence of chronic infections with hepatitis C virus (HCV), human immunodeficiency virus (HIV), and Helicobacter pylori, and should be considered in the differential diagnosis of primary immune thrombocytopenia (ITP). Studies have shown that on diagnosis of infections, treatment of the primary disease often results in substantial improvement or complete recovery of the thrombocytopenia. In patients with thrombocytopenia due to HCV-related chronic liver disease, the use of eltrombopag, a thrombopoietin receptor agonist, normalizes platelet levels, thereby permitting the initiation of antiviral therapy. Antiviral therapy with highly active antiretroviral therapy for HIV has aided in platelet recovery, with a corresponding decrease in circulating viral load. Thrombocytopenia in the absence of other disease symptoms requires screening for H. pylori, especially in countries such as Japan, where there is a high prevalence of the disease and the chances of a platelet response to eradication therapy are high.

Pathobiology of secondary immune thrombocytopenia

Primary immune thrombocytopenic purpura (ITP) remains a diagnosis of exclusion both from nonimmune causes of thrombocytopenia and immune thrombocytopenia that develops in the context of other disorders (secondary immune thrombocytopenia). The pathobiology, natural history, and response to therapy of the diverse causes of secondary ITP differ from each other and from primary ITP, so accurate diagnosis is essential. Immune thrombocytopenia can be secondary to medications or to a concurrent disease, such as an autoimmune condition (eg, systemic lupus erythematosus [SLE], antiphospholipid antibody syndrome [APS], immune thyroid disease, or Evans syndrome), a lymphoproliferative disease (eg, chronic lymphocytic leukemia or large granular T-lymphocyte lymphocytic leukemia), or chronic infection, eg, with Helicobacter pylori, human immunodeficiency virus (HIV), or hepatitis C virus (HCV). Response to infection may generate antibodies that cross-react with platelet antigens (HIV, H pylori) or immune complexes that bind to platelet Fcγ receptors (HCV), and platelet production may be impaired by infection of megakaryocyte (MK) bone marrow–dependent progenitor cells (HCV and HIV), decreased production of thrombopoietin (TPO), and splenic sequestration of platelets secondary to portal hypertension (HCV). Sudden and severe onset of thrombocytopenia has been observed in children after vaccination for measles, mumps, and rubella or natural viral infections, including Epstein-Barr virus, cytomegalovirus, and varicella zoster virus. This thrombocytopenia may be caused by cross-reacting antibodies and closely mimics acute ITP of childhood. Proper diagnosis and treatment of the underlying disorder, where necessary, play an important role in patient management.

Other immune thrombocytopenias

Immune thrombocytopenic purpura (ITP) can be classified as primary (known also as idiopathic thrombocytopenic purpura) or as secondary to an underlying condition such as a malignant or nonmalignant disorder. Commonly occurring conditions associated with secondary ITP include lymphoproliferative disorders (chronic lymphocytic leukemia [CLL], Hodgkin's disease and non-Hodgkin's lymphomas), autoimmune collagen vascular diseases (systemic lupus erythematosus [SLE], thyroid disease, antiphospholipid syndrome [APS]), and chronic infections (human immunodeficiency virus [HIV], Helicobacter pylori, hepatitis C virus [HCV]). The mechanism of platelet destruction in thrombocytopenias associated with lymphoproliferative disorders and collagen vascular diseases is identical to the autoimmune mechanism seen in primary ITP. Drug-induced thrombocytopenias are uncommon and generally resolve quickly upon drug discontinuation, but are often attributed to other causes. Platelet destruction in infection-associated ITP occurs via various mechanisms including accelerated platelet clearance due to immune complex disease as seen in HIV infection or cross-reactivity of anti-platelet glycoprotein antibodies and viral antigens in HIV, HCV, and H pylori infections (antigenic mimicry). In patients with HCV-related cirrhotic liver disease, splenic sequestration secondary to portal hypertension and decreased production of thrombopoietin may further contribute to development of thrombocytopenia. The current treatment paradigm for secondary ITP varies according to the underlying condition. Standard treatments for primary ITP (corticosteroids, IVIG, anti-D, splenectomy) are often successful in secondary ITP. In cases of ITP with H pylori and HCV infection, treatment should focus on the underlying disorder.

Does H. Pylori infection play a role in idiopathic thrombocytopenic purpura and in other autoimmune diseases?

Idiopathic thrombocytopenic purpura (ITP), an autoimmune disease caused by sensitization of platelets by autoantibodies leading to platelet destruction, has been associated with some infectious agents, including Helicobacter pylori. The study by Suzuki et al., published in this issue, provides further evidence of the role of H. pylori infection in the pathogenesis of ITP, as confirmed by the increase in the platelet count in patients with ITP, following H. pylori eradication. Interestingly, H. pylori infection has also been shown to play a role in other diseases in which autoimmune mechanisms may be predominant, such as acne rosacea, idiopathic chronic urticaria, and atherosclerosis. While H. pylori eradication is usually recommended in patients with gastric diseases, there are no specific indications for extraalimentary diseases. In the light of the recent findings, a revision of the current guidelines for the management of H. pylori infection may be needed.

Helicobacter pylori eradication: novel therapy for immune thrombocytopenic purpura? A review of the literature

Eradication of Helicobacter pylori (H. pylori ) from the gastric mucosa has been associated with improvement of several systemic diseases, including immune thrombocytopenic purpura (ITP). Over the last 5 years, several studies have reported improved platelet counts in H. pylori-positive ITP patients following standard triple H. pylori eradication therapy. Review of published studies in which eradication of H. pylori has been performed in the ITP population indicates an overall response rate of 52% in 193 subjects in whom H. pylori was eradicated. Cohorts from Japan and Italy report higher response rates. There is no established mechanism to explain how this organism, which does not invade the gastric mucosa, could be implicated in the pathogenesis of this immune-based platelet disorder. Several theories including molecular mimicry, platelet aggregation, and immunomodulatory effects of macrolides have been proposed to explain the platelet response to anti-H. pylori therapy. Large randomized-controlled studies enrolling patients from various ethnic backgrounds will be necessary to determine the response rate and mechanism of response and to gain a better understanding of the pathogenesis of ITP.

Can eradication therapy for Helicobacter pylori really improve the thrombocytopenia in idiopathic thrombocytopenic purpura? Our experience and a literature review

Helicobacter pylori has recently been postulated to play a role in the pathogenesis of autoimmune diseases, including idiopathic thrombocytopenic purpura (ITP). We investigated the prevalence of H pylori infection and the effects of its eradication in 61 patients with ITP. H pylori infection was found in 50 patients (83%), an incidence significantly higher than not only healthy volunteers in Japan (60%) but also subjects in other reported ITP series (approximately 43%-71%). In our study, the mean age of H pylori-positive ITP patients (58.0 years) was significantly higher than that of H pylori-negative ITP patients (40.5 years). Bacterium eradication efforts were performed in 29 infected ITP patients and succeeded in 27 patients (93%). The 29 patients with eradicated H pylori infections showed significant increases in platelet counts compared with patients with uneradicated infections or who were H pylori-negative. During the follow-up period (median, 11.0 months), 16 (55%) of 29 patients achieved a major or a minor response. The patients who achieved a major response had not received previous prednisolone therapy, suggesting a relationship between prednisolone therapy and the response to eradication efforts. The assessment of H pylori infection and its eradication should be attempted in cases of ITP, because this approach may be a good new strategy for treating some ITP patients, especially elderly Japanese patients. Some regional factors have been suggested as causes of H pylori-associated ITP.

Antibody against CD20 in patients with B cell malignancy

Cancer patients may make antibodies against antigens on the surface of their malignant cells due either to the expression of unique antigens or to dysregulated responses to self antigens. Patients with B cell malignancy frequently produce autoantibodies and may therefore be a source of immunoglobulin genes for the production of phage display antibody libraries directed against tumour-associated antigens. Patients with autoimmune disease have circulating antibodies against lymphocyte surface antigens, and may also provide a good starting point for the production of a library of lymphocyte-reactive antibody structures. In this study, plasma and serum samples from patients with B cell malignancy or Sjogren's syndrome and from healthy controls were screened for antibodies against the B cell membrane antigens CD20. While the majority of samples showed very low reactivity, some individuals did show significant and reproducible binding to CD20. To identify a good donor for library construction, it would be advisable to screen donors for antibody against the antigens of interest.

Initial observations on the efficacy of highly active antiretroviral therapy in the treatment of HIV-associated autoimmune thrombocytopenia

BACKGROUND

Immune thrombocytopenic purpura (ITP) occurs in as many as 40% of patients infected with the human immunodeficiency virus (HIV). We sought to evaluate the effect of highly active antiretroviral therapy (HAART) on platelet counts in such patients.

METHODS

Data collected from 11 homosexual men with HIV-associated ITP and < or = 50 x 10(9) platelets were analyzed after they were placed on HAART. At initial evaluation, 7 patients were antiretroviral naive, 2 were taking zidovudine alone, and 2 were receiving combination antiretroviral therapy for known HIV infection. For 6 patients with <30 x 10(9) platelets, prednisone was initially coadministered with HAART. The primary outcome measure was the platelet count response to HAART, which was measured weekly until counts had normalized on 3 consecutive occasions, then every 3 months while on HAART. Secondary outcome measures were HIV-viral RNA levels and CD4+ cell counts.

RESULTS

One month after the initiation of HAART, 10 evaluable patients had an increase in mean platelet count. This improvement was sustained at 6 and 12 months' follow-up for 9 of 10 evaluable patients. Increases in mean platelet count at 6 and 12 months of the 9 responders were statistically significant. The range of follow-up in the 9 responders is 21 to 46 months (median, 30 months), with no thrombocytopenic relapses. The 9 long-term platelet responders have been maintained on HAART and at 12 months had a mean reduction of > 1.5 log10 in HIV viral RNA serum levels and a marked improvement in CD4+ T-lymphocyte cell count.

CONCLUSION

HAART seems to be effective in improving platelet counts in the setting of HIV-associated ITP, enhancing CD4+ cell counts, and reducing HIV viral loads.

Impaired liver function and retroviral activity are risk factors contributing to HIV-associated thrombocytopenia. Swiss HIV Cohort Study

OBJECTIVE

To investigate the relationship between thrombopoetin (TPO) serum levels and HIV-associated thrombocytopenia.

DESIGN AND METHODS

The relationship between TPO levels and severity of HIV-associated thrombocytopenia was investigated. Thirty-eight patients (19 patients with 30-96x10(9) platelets/l and 19 patients with <10x10(9) platelets/l) were matched with 38 HIV-positive non-thrombocytopenic patients (>150x10(9) platelets/l).

RESULTS

HIV-positive patients with normal platelet counts had a median TPO serum level of 137 pg/ml. Patients with 30-96x10(9) platelets/l had decreased TPO levels with a median of 90 pg/ml (P = 0.016), and were more likely to have elevated serum aspartate-transferase levels (P<0.001) and hepatomegaly by palpation or ultrasound imaging (P = 0.005). The median TPO serum level of HIV-infected patients with severe thrombocytopenia was 110 pg/ml (non-significant). All patients with severe thrombocytopenia were positive for antibodies against hepatitis B virus core antigen, compared with 80% of HIV-infected persons without thrombocytopenia. Patients with severe thrombocytopenia were more likely to have high HIV replication compared to patients with normal platelet counts (P = 0.02), and reduction of plasma HIV-1 RNA levels was associated with increasing platelet counts. Severe thrombocytopenia was not associated with liver disease.

CONCLUSIONS

Liver disease predisposes for low TPO serum levels and mild thrombocytopenia. High retroviral activity predisposes for severe, immune thrombocytopenic purpura-like thrombocytopenia. At least two distinct categories of severe HIV-associated thrombocytopenia exist, one responsive to antiretroviral treatment and one non-responsive to antiretroviral treatment.

Autoimmune diseases and Helicobacter pylori infection

In the last few years several studies have been performed on the association between H. pylori infection and a miscellany of extragastric disorders which also include autoimmune diseases. In particular, emerging evidence seems to give a potential role for H. pylori in ischaemic heart disease via a cross mimicry between antibodies against heat shock protein 65 which are produced in the consequence of infection, but which are also expressed in atherosclerotic lesions. In cases of healing of Sjogren syndrome and Schonlein-Henoch, purpura have also been reported. A recent study, moreover, showed that eradication of H. pylori infection may be effective in the disappearance of autoimmune thrombocytopenia. Finally, a role for H. pylori has also been postulated in other autoimmune diseases such as membranous nephropathy and some acute immune polyneuropathies. The mechanisms behind these clinical observations still remain unclear. However, if confirmed, these findings could revise the diagnostic and therapeutic approach to diseases previously considered as idiopathics.

Characterization of HIV-1-specific antibodies and HIV-1-crossreactive antibodies to platelets in HIV-1-infected haemophiliac patients

Sera from HIV-1-infected haemophiliacs were examined for human immunodeficiency virus (HIV) specific antibodies and for platelet crossreactive antibodies. Using HIV sepharose 4B affinity columns for serum absorption, antibodies against various HIV antigens, including HIV lysate. HIV-p24 and HIV-gp120, were eluted either by low or by high pH buffer. The eluates were examined by ELISA for HIV specificity and by flow cytometry for platelet crossreactivity. Two types of HIV antibodies could be eluted, i.e. acid-sensitive and alkaline-sensitive antibodies. HIV antibodies were obtained in 26/29 acid eluates and in 25/29 of the alkaline eluates from HIV-lysate columns; 96% (25/26) of the acid-eluted antibodies were HIV-specific but 48% (12/ 25) of the alkaline-eluted antibodies also showed crossreactivity to platelets. Of the 20 alkaline-eluted HIV-p24 antibodies, 40% (8/20) reacted specifically with HIV-p24 and 60% (12/20) were platelet crossreactive. In contrast, of the alkaline-eluted HIV-gp120 antibodies (n=17), 88% (15/17) were HIV gp120-specific and only 12% (2/17) were platelet crossreactive. Western blot analysis of platelets demonstrated that the anti-p24 antibodies recognized three bands with approximate molecular weights of 72000 to 95000. 69% of the serum antiplatelet antibodies showed platelet glycoprotein IIbIIIa specificity. Anti-HIV antibodies could be eluted from platelets. Hence, platelet crossreactive antibodies in HIV infection are primarily alkaline-sensitive and are associated predominantly with HIV p24 antibody; these antibodies may play a role in the immune thrombocytopenia of HIV-infected haemophiliacs.

Antigenic homology of HIV-1 GP41 and human platelet glycoprotein GPIIIa (integrin beta3)

Fifty-eight of 89 serum samples (65.17%) from HIV-1-infected individuals at various disease stages contain antibodies that react with a platelet peptide located in the cytoplasmic domain of integrin beta3, glycoprotein GPIIIa (aa749-761; sequence DRKEFAKFEEERA). Rabbit polyclonal antibodies raised against the synthetic platelet peptide also react with the structurally homologous HIV-1 gp41-derived peptide (EKNEQELLELDKW(A)) and bind to a Western blot band with molecular weight corresponding to HIV-1 gp41. These findings point to molecular mimicry between HIV-1 and a human membrane protein found in platelets and other cells that could be of pathologic consequence.

Surveillance for thrombocytopenia in persons infected with HIV: results from the multistate Adult and Adolescent Spectrum of Disease Project

Thrombocytopenia in persons infected with HIV is prevalent and has numerous causes. To study the occurrence, associations, and effect on survival of thrombocytopenia in HIV-infected persons, we used surveillance data from a longitudinal survey of the medical records of 30,214 HIV-infected patients who received medical care from January 1990 through August 1996 in more than 100 medical clinics in 10 U.S. cities. Thrombocytopenia was defined as a physician diagnosis of thrombocytopenia or a platelet count of < 50,000 platelets/ microliter. Analysis of associations of thrombocytopenia was conducted using logistic regression. In HIV+ patients, the 1-year incidence [corrected] of thrombocytopenia was 8.7% in persons with one or more AIDS-defining opportunistic illnesses (clinical AIDS), 3.1% in patients with a CD4 count < 200 cells/mm3 but not clinical AIDS (immunologic AIDS), and 1.7% in persons without clinical or immunologic AIDS. The incidence of thrombocytopenia was associated with clinical AIDS (adjusted odds ratio [AOR] 2.2; 99% confidence interval [CI] 1.7-3.0), immunologic AIDS (AOR 1.5, CI 1.0-2.1), history of injecting drug use (AOR 1.4, CI 1.0-1.9), anemia (AOR 5.0, CI 3.8-6.7), lymphoma (AOR 3.7, CI 1.3-10.6), and black race (AOR 0.7, CI 0.5-0.9). After controlling for anemia, clinical AIDS, CD4 count, neutropenia, antiretroviral therapy, and Pneumocystis carinii pneumonia prophylaxis, thrombocytopenia was significantly associated with decreased survival (risk ratio 1.7; 95% CI, 1.6-1.8). Thrombocytopenia in HIV-infected persons is an important clinical condition associated with shorter survival.

No evidence of a higher risk of progression to AIDS in patients with HIV-1-related severe thrombocytopenia

The prognostic role of platelet (PLT) counts was evaluated in a cohort of 1,533 HIV-1-infected subjects followed for a median of 21 months. Thrombocytopenia (TCP), defined as a PLT count < or = 100 x 10(9)/L was present at enrollment in 11.2% of cases, with counts < or = 50 x 10(9)/L (severe TCP) in 5.3%. With the subjects with normal PLT counts (PLT >150 x 10(9)/L) as the reference group, the relative risk of developing acquired immunodeficiency syndrome (AIDS) was 0.8 [95% confidence interval (CI) 0.5-1.3, p = 0.4] for subjects with severe TCP, 2.1 (95% CI 1.4-3.1, p = 0.002) for those with PLT counts ranging from 51 to 100 x 10(9)/L (moderate TCP), and 1.6 (95% CI 1.2-2.1, p = 0.0004) for those with borderline PLT values (PLT ranging from 101 to 150 x 10(9)/L). Most of the risk increase associated with moderate TCP and borderline PLT values was explained by a higher prevalence of subjects with an older age and lower CD4+ cell counts. However, at multivariable analysis considering age, sex, risk group, and zidovudine (ZDV) treatment, the risk for subjects with severe TCP remained significantly lower than that for subjects with moderate TCP and borderline values. These results suggest the existence of different types of HIV-1-associated TCP and also suggest that severe TCP (which often arises in the early phases of infection) is not related to disease progression.

Antibodies to p24 antigen do not specifically detect HIV-infected lymphocytes in AIDS patients

A flow cytometric assay (FCA), which detects the p24 antigen in HIV-infected cell lines and in peripheral blood mononuclear cells (PBMC) of AIDS patients, has been described in several studies. However, the results presented here clearly show that this p24-FCA, although useful for the analysis of HIV infection of cells in vitro, does not specifically detect HIV-infected PBMC from patients. Isotype control antibodies also stained PBMC from HIV-infected patients to a greater degree than the PBMC from healthy controls. Furthermore, the CD4-negative lymphocytes, which are generally not infected with HIV, were also found to stain with anti-p24. Finally, no enrichment of HIV-infected cells was found in the FACS-purified CD4+p24+ lymphocytes, compared to the CD4+p24- cell fraction. The p24-FCA, therefore, was not useful for determining the percentage of infected PBMCs from HIV-infected individuals.

Thrombocytopenia associated with hepatitis C viral infection

BACKGROUND/AIMS

We investigated whether chronic hepatitis C infection is associated with thrombocytopenia.

METHODS/RESULTS

Thrombocytopenia (<15 x 10(4) platelets/mu l) was diagnosed in 151 of 368 patients (41.0%) with chronic hepatitis C, a significantly higher proportion than that observed in patients with chronic hepatitis B (18.9%, p < 0.01). Elevated titers of platelet-associated immunoglobulin G were observed in 88.1% of patients with chronic hepatitis C and in 47.1% of patients with chronic hepatitis B. Platelet-associated immunoglobulin G titers were significantly higher in patients with chronic hepatitis C (87.3 +/- 10.1 ng/10(7) cells) vs. those with chronic hepatitis B (30.3 +/- 6.4) or the control subjects (p < 0.01). There was a significant negative correlation between platelet-associated immunoglobulin G titers and platelet counts in both chronic hepatitis C and B cases. Platelet-associated immunoglobulin G titers were significantly higher in patients with type C cirrhosis than in those with type B cirrhosis. Interestingly, HCV-RNA was detected by RT-PCR in the platelets from 11 of 14 patients with hepatitis C virus.

CONCLUSIONS

These data indicate that chronic infection with hepatitis C virus may produce a significant autoimmune reaction to platelets, leading to thrombocytopenia.

PCR as a confirmatory test for human immunodeficiency virus type 1 infection in individuals with indeterminate western blot (immunoblot) profiles

A combination of two PCR systems which amplify human immunodeficiency virus type 1 (HIV-1) gag and pol DNA was used to elucidate the HIV-1 infection status of a group of individuals screening positive for anti-HIV but having indeterminate Western blot (immunoblot) profiles. The results obtained suggest PCR could be used to resolve such cases.

Anti-human immunodeficiency virus type 1 antibodies of noninfected subjects are not related to autoantibodies occurring in systemic diseases

Indeterminate Western blot (WB) (immunoblot) patterns for anti-human immunodeficiency virus type 1 (HIV-1) antibodies are often observed when testing serum samples from noninfected individuals. We investigated here the possible involvement of some frequently occurring autoantibodies (anti-SmB/B', U1snRNP [68 kDa, A, and C], Ro/SS-A [60 and 52 kDa], and Jo-1) in the generation of such indeterminate HIV-1 WB. In particular, the role of a reported sequence homology between p24 gag and the SmB/B' autoantigen was investigated. Serum samples were obtained from 50 healthy controls, 51 patients with systemic lupus erythematosus (SLE), 46 with systemic sclerosis, 6 with Sjögren's disease, 3 with mixed connective tissue disease, and 41 healthy subjects with persistent indeterminate HIV-1 WB. Reactivity to HIV-1 p24 gag was slightly but not significantly more frequent in patients with SLE than in controls (25.5% versus 14.0%; P > 0.1), whereas reactivity to HIV-1 p17 gag was significantly more frequent in the former subjects (23.5% versus 8.0%; P = 0.03). Simultaneous reactivity to p17 and p24 was observed in patients with SLE (11.8%; P = 0.014) or systemic sclerosis (8.7%; P = 0.049) but not in controls. There was no association found between the presence of any autoantibody and the occurrence of indeterminate HIV-1 WB nor between the presence of p24-reactive antibodies and anti-SmB/B'; this indicates that most p24-reactive antibodies are directed to epitopes other than the proline-rich sequences shared by p24 gag and SmB/B'.