Malarial antibodies and autoantibodies to heart and other tissues in the immigrant and indigenous peoples of Uganda

A rare case of sudden death due to endomyocardial fibrosis in Italy: A differential diagnosis with other causes of restrictive cardiomyopathy

A 45-years-old Indonesian woman was admitted to the hospital with nausea, vomiting, abdominal pain and tachyarrhythmia. Atrial fibrillation was found at ECG, blood tests showed mild hepatic function alterations. Radiological exams showed bilateral pleural effusions, ascites, hepatomegaly. Systolic and diastolic functions of the left ventricle were found to be strongly compromised at US. Physical conditions and laboratory results worsened rapidly, followed by multi organ failure. Death occurred 28 hours after admission. An autopsy was performed to clarify the cause of death and investigated medical malpractice. External examination showed jaundice skin and at internal examination bilateral pleural and pericardial effusions, ascites, mild cardiomegaly, ventricular endocardial fibrosis, a thrombus in tight junction to the left ventricular wall and hepatic necrosis were observed. Histological investigations revealed a massive endomyocardial fibrosis, detected through Azan-Mallory and Verhoef-Van-Gieson stain, and confirmed the presence of hepatic and renal necrosis. Toxicological and microbiological investigations were negative. The cause of death was a global cardiac dysfunction caused by a restrictive cardiomyopathy in an Indonesian woman affected by an undiagnosed and asymptomatic endomyocardial fibrosis. In this case, autopsy and histopathological investigations were fundamental to diagnose an occult endomyocardial fibrosis, which is an idiopathic disorder of tropical and subtropical regions of the world. The not common incidence of this disease in our country and its unusual clinical onset were at first perceived as a medical malpractice from the relatives. Consequently, the clinical aspects of the case intertwine with the medicolegal implications concerning the undiagnosed disease and the causality with the patient's death.

Endomyocardiofibrosis: A Systematic Review

Endomyocardiofibrosis was described first time in Uganda as an infrequent restrictive cardiomyopathy with a poor prognosis, characterized by fibrosis of the ventricular subendocardium and severe restrictive physiology leading to difficult therapeutic management and frequently associated with hypereosinophilic syndrome. Its higher prevalence in the tropics and its relationship in some cases with hypereosinophilic endocarditis has led to the search for genetic, infectious, autoimmune and nutritional causes, but its etiology remains unclear. It is a rare cardiomyopathy, difficult to diagnose and with a nonexistent effective treatment. Imaging methods such as echocardiography and cardiac magnetic resonance are essential for the initial diagnosis, although endomyocardial biopsy establishes the definitive diagnosis. Immunosuppressive treatment is only useful in the early stages of the disease and usually ineffective if installed late when signs of heart failure are present. Surgical treatment is generally palliative.

Endomyocardial Fibrosis: an Update After 70 Years

PURPOSE OF REVIEW

This review aims at highlighting the need to better understand the pathogenesis and natural history of endomyocardial fibrosis when set against its changing endemicity and disease burden, improvements in diagnosis, and new options for clinical management.

RECENT FINDINGS

Progress in imaging diagnostic techniques and availability of new targets for drug and surgical treatment of heart failure are contributing to earlier diagnosis and may lead to improvement in patient survival. Endomyocardial fibrosis was first described in Uganda by Davies more than 70 years ago (1948). Despite its poor prognosis, the etiology of this neglected tropical restrictive cardiomyopathy still remains enigmatic nowadays. Our review reflects on the journey of scientific discovery and construction of the current guiding concepts on this mysterious and fascinating condition, bringing to light the contemporary knowledge acquired over these years. Here we describe novel tools for diagnosis, give an overview of the improvement in clinical management, and finally, suggest research themes that can help improve patient outcomes focusing (whenever possible) on novel players coming into action.

Vivax infection alters peripheral B-cell profile and induces persistent serum IgM

B cell-mediated humoral responses are essential for controlling malarial infection. Studies have addressed the effects of Plasmodium falciparum infection on peripheral B-cell subsets but not much is known for P. vivax infection. Furthermore, majority of the studies investigate changes during acute infection, but not after parasite clearance. In this prospective study, we analysed peripheral B-cell profiles and antibody responses during acute P. vivax infection and upon recovery (30 days post-treatment) in a low-transmission area in India. Dengue patients were included as febrile-condition controls. Both dengue and malaria patients showed a transient increase in atypical memory B cells during acute infection. However, transient B cell-activating factor (BAFF)-independent increase in the percentage of total and activated immature B cells was observed in malaria patients. Naïve B cells from malaria patients also showed increased TLR4 expression. Total IgM levels remained unchanged during acute infection but increased significantly at recovery. Serum antibody profiling showed a parasite-specific IgM response that persisted at recovery. A persistent IgM autoantibody response was also observed in malaria but not dengue patients. Our data suggest that in hypoendemic regions acute P. vivax infection skews peripheral B-cell subsets and results in a persistent parasite-specific and autoreactive IgM response.

[Tropical endomyocardial fibrosis: Perspectives]

Tropical endomyocardial fibrosis (FET) is a leading cause of heart failure and the most common restrictive cardiomyopathy worldwide. Extensive fibrosis of the ventricular endocardium causing architectural distortion, impaired filling and valvular insufficiency define the disease. Confined to peculiar and limited geographical areas, the aetiology remains blurred and it carries a grim prognosis. The changing burden reported recently in some endemic areas and the refinement of diagnostic tools have emphasized alternative routes for understanding and treatment of the disease.

Tropical Endomyocardial Fibrosis: Natural History, Challenges, and Perspectives

Tropical endomyocardial fibrosis (EMF) is a neglected disease of poverty that afflicts rural populations in tropical low-income countries, with some certain high-prevalence areas. Tropical EMF is characterized by the deposition of fibrous tissue in the endomyocardium, leading to restrictive physiology. Since the first descriptions in Uganda in 1948, high-frequency areas for EMF have included Africa, Asia, and South America. Although there is no clear consensus on a unified hypothesis, it seems likely that dietary, environmental, and infectious factors may combine in a susceptible individual to give rise to an inflammatory process leading to endomyocardial damage and scar formation. The natural history of EMF includes an active phase with recurrent flare-ups of inflammation evolving to a chronic phase leading to restrictive heart failure. In the chronic phase, biventricular involvement is the most common presentation, followed by isolated right-sided heart disease. Marked ascites out of proportion to peripheral edema usually develops as a typical feature of EMF. EMF carries a very poor prognosis. In addition to medical management of heart failure, early open heart surgery (endocardectomy and valve repair/replacement) appears to improve outcomes to some extent; however, surgery is technically challenging and not available in most endemic areas. Increased awareness among health workers and policy makers is the need of the hour for the unhindered development of efficient preventive and therapeutic strategies.

Endomyocardial fibrosis: A form of endemic restrictive cardiomyopathy

Endomyocardial fibrosis is a form of endemic restrictive cardiomyopathy that affects mainly children and adolescents, and is geographically restricted to some poor areas of Africa, Latin America and Asia. It is a condition with high morbidity and mortality, for which no effective therapy is available. Although several hypotheses have been proposed as triggers or causal factors for the disease, none are able to explain the occurrence of the disease worldwide. In endemic areas of Africa endomyocardial fibrosis is as common a cause of heart failure as rheumatic heart disease, accounting for up to 20% of cases of heart failure and imposes a considerable burden to the communities and the health systems. However, due to lack of resources for research in these areas, the exact epidemiology, etiology and pathogenesis remain unknown, and the natural history is incompletely understood. We here review the main aspects of epidemiology, natural history, clinical picture and management of endomyocardial fibrosis, proposing new ways to increase research into this challenging and neglected cardiovascular disease.

Lack of evidence of myocardial damage in children with Plasmodium falciparum severe and complicated malaria from an endemic area for endomyocardial fibrosis

Malaria is among the factors thought to be involved in the pathogenesis of endomyocardial fibrosis (EMF), a restrictive cardiomyopathy of unclear etiology, with no specific therapy, which affects predominantly children and adolescents. In Africa, regions endemic with EMF are also areas with high prevalence of malaria. We studied 47 consecutive children aged 5- to 15-years old and concluded that myocardial damage and dysfunction are rare in severe and complicated Plasmodium falciparum malaria cases in children.

Presence of circulating anti-myosin antibodies in endomyocardial fibrosis

Background

Endomyocardial Fibrosis (EMF) is a tropical restrictive cardiomyopathy of unknown etiology with high prevalence in Sub-Saharan Africa, for which it is unclear whether the primary target of injury is the endocardial endothelium, the subendocardial fibroblast, the coronary microcirculation or the myocyte. In an attempt to explore the possibility of endocardial lesions being a result of an immune response against the myocyte we assessed the presence and frequency of circulating anti-myocardial antibodies in EMF patients.

Methodology/Principal Findings

EMF classification, assessment of severity and staging was based on echocardiography. We used sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) of myocardial proteins followed by western blotting to screen serum samples for antiheart antibodies G and M classes. The degree of serum reactivity was correlated with the severity and activity of EMF. We studied 56 EMF patients and 10 healthy controls. IgG reactivity against myocardial proteins was stronger and more frequent in patients with EMF when compared to controls (30/56; 53.6% vs. 1/10; 10%, respectively). IgM reactivity was weak in both groups, although higher in EMF patients (11/56; 19.6%) when compared to controls (n = 0). EMF patients showed greater frequency and reactivity of IgG antibodies against myocardial proteins of molecular weights 35 kD, 42 kD and 70 kD (p values <0.01, <0.01 and <0.05 respectively).

Conclusions

The presence of antibodies against myocardial proteins was demonstrated in a subset of EMF patients. These immune markers seem to be related with activity and might provide an adjunct tool for diagnosis and classification of EMF, therefore improving its management by identifying patients who may benefit from immunosuppressive therapy. Further research is needed to clarify the role of autoimmunity in the pathogenesis of EMF.

Endomyocardial Fibrosis is a tropical disease in which the heart cannot open properly to receive blood due to a scar that covers its inner layer. It affects mainly children and adolescents, and has a poor prognosis because the cause and mechanisms of scarring are unknown. The conventional treatment is frustrating and does not alter the natural history of the disease. Despite affecting several million people worldwide there has been little investigation on the mechanisms of the disease or drug development to improve its prognosis. In this study we investigate the presence of antibodies against the myocardial cells of African patients with severe and advanced EMF aiming at uncovering new pathways for the disease. Our results reveal that EMF patients have anti-myocardial antibodies in their blood. The reaction of these antibodies with the heart may be one of the mechanisms involved in the genesis of the fibrotic lesions. This knowledge may help in diagnosing the condition and provide alternatives for its management, using drugs that reduce the impact of the circulating antibodies in the cardiac tissue. The significance of these results needs confirmation on studies involving larger number of subjects due to frequent finding of antiheart antibodies in African populations with heart failure of any cause.

IgG autoantibody to brain beta tubulin III associated with cytokine cluster-II discriminate cerebral malaria in central India

BACKGROUND

The main processes in the pathogenesis of cerebral malaria caused by Plasmodium falciparum involved sequestration of parasitized red blood cells and immunopathological responses. Among immune factors, IgG autoantibodies to brain antigens are increased in P. falciparum infected patients and correlate with disease severity in African children. Nevertheless, their role in the pathophysiology of cerebral malaria (CM) is not fully defined. We extended our analysis to an Indian population with genetic backgrounds and endemic and environmental status different from Africa to determine if these autoantibodies could be either a biomarker or a risk factor of developing CM.

METHODS/PRINCIPAL FINDINGS

We investigated the significance of these self-reactive antibodies in clinically well-defined groups of P. falciparum infected patients manifesting mild malaria (MM), severe non-cerebral malaria (SM), or cerebral malaria (CM) and in control subjects from Gondia, a malaria epidemic site in central India using quantitative immunoprinting and multivariate statistical analyses. A two-fold complete-linkage hierarchical clustering allows classifying the different patient groups and to distinguish the CM from the others on the basis of their profile of IgG reactivity to brain proteins defined by PANAMA Blot. We identified beta tubulin III (TBB3) as a novel discriminant brain antigen in the prevalence of CM. In addition, circulating IgG from CM patients highly react with recombinant TBB3. Overall, correspondence analyses based on singular value decomposition show a strong correlation between IgG anti-TBB3 and elevated concentration of cluster-II cytokine (IFNgamma, IL1beta, TNFalpha, TGFbeta) previously demonstrated to be a predictor of CM in the same population.

CONCLUSIONS/SIGNIFICANCE

Collectively, these findings validate the relationship between antibody response to brain induced by P. falciparum infection and plasma cytokine patterns with clinical outcome of malaria. They also provide significant insight into the immune mechanisms associated to CM by the identification of TBB3 as a new disease-specific marker and potential therapeutic target.

Endomyocardial fibrosis: still a mystery after 60 years

The pathologist Jack N. P. Davies identified endomyocardial fibrosis in Uganda in 1947. Since that time, reports of this restrictive cardiomyopathy have come from other parts of tropical Africa, South Asia, and South America. In Kampala, the disease accounts for 20% of heart disease patients referred for echocardiography. We conducted a systematic review of research on the epidemiology and etiology of endomyocardial fibrosis. We relied primarily on articles in the MEDLINE database with either “endomyocardial fibrosis” or “endomyocardial sclerosis” in the title. The volume of publications on endomyocardial fibrosis has declined since the 1980s. Despite several hypotheses regarding cause, no account of the etiology of this disease has yet fully explained its unique geographical distribution.

Self-reactivities to the non-erythroid alpha spectrin correlate with cerebral malaria in Gabonese children

BACKGROUND

Hypergammaglobulinemia and polyclonal B-cell activation commonly occur in Plasmodium sp. infections. Some of the antibodies produced recognize self-components and are correlated with disease severity in P. falciparum malaria. However, it is not known whether some self-reactive antibodies produced during P. falciparum infection contribute to the events leading to cerebral malaria (CM). We show here a correlation between self-antibody responses to a human brain protein and high levels of circulating TNF alpha (TNFalpha), with the manifestation of CM in Gabonese children.

METHODOLOGY

To study the role of self-reactive antibodies associated to the development of P. falciparum cerebral malaria, we used a combination of quantitative immunoblotting and multivariate analysis to analyse correlation between the reactivity of circulating IgG with a human brain protein extract and TNFalpha concentrations in cohorts of uninfected controls (UI) and P. falciparum-infected Gabonese children developing uncomplicated malaria (UM), severe non-cerebral malaria (SNCM), or CM.

RESULTS/CONCLUSION

The repertoire of brain antigens recognized by plasma IgGs was more diverse in infected than in UI individuals. Anti-brain reactivity was significantly higher in the CM group than in the UM and SNCM groups. IgG self-reactivity to brain antigens was also correlated with plasma IgG levels and age. We found that 90% of CM patients displayed reactivity to a high-molecular mass band containing the spectrin non-erythroid alpha chain. Reactivity with this band was correlated with high TNFalpha concentrations in CM patients. These results strongly suggest that an antibody response to brain antigens induced by P. falciparum infection may be associated with pathogenic mechanisms in patients developing CM.

Identification of karyopherin beta as an immunogenic antigen of the malaria parasite using immune mice and human sera

A differential immunoscreening of the lambdagt11 Plasmodium falciparum genomic expression library was carried out using anti-P. yoelii sera (convalescent-phase mouse sera) and immune sera collected from healthy adults, to identify novel cross-reactive and possibly protective antigens of the parasite. One clone, with an insert size of 1132 bp that reacted strongly with both the sera was selected. The insert was found to be a part of the P. falciparum karyopherin beta (PfKbeta) homologue. RT-PCR and Northern blot analysis confirmed the expression of PfKbeta in the blood stages of the parasite. The approximately 110 kDa protein was localized in the cytoplasm at the ring and trophozoite, and in the parasitophorous vacuole at the schizont stage. Two large fragments of PfKbeta representing the N- and C-terminal halves were expressed in E. coli. The recombinant proteins were highly immunogenic in mice, and also found to be the target for immune response in natural infections of Plasmodium spp. Anti-sera against the protein showed a low level of anti-parasitic activity. Immunization with recombinant PfKbeta fragments was only partially protective against a heterologous challenge infection in mice. Our results show that the parasite releases a highly immunogenic, cytoplasmic protein into the host which may not contribute to the development of protective immunity.

Influence of CD4+CD25+ T cells on Plasmodium berghei NK65 infection in BALB/c mice

CD4(+) T cells co-expressing CD25 (CD4(+)CD25(+) T cells) have been identified as immunoregulatory suppressors modulating autoimmune response. Beside that, autoimmune response was supposed to be associated with malaria infection. Based on these data, we hypothesised that CD4(+)CD25(+) T cells may influence protective immunity to malaria parasites, while suppressing autoimmune response arising throughout the course of malarial infection. To test this possibility, we evaluated the kinetics of CD4(+)CD25(+) T cells during malaria infection and investigated the influence of CD25 depletion by anti-mouse CD25 monoclonal antibody (PC61) on the infection, using a mouse model of premunition to Plasmodium berghei NK65 malaria. The results showed that, during exacerbation of P. berghei NK65 infection, the proportion of CD4(+)CD25(+) T cells among CD4(+) T cells decreased, although that of CD4(+) T cells increased. CD25 depletion clearly delayed the growth of parasitaemia during parasite challenge, particularly in immunised mice. These findings demonstrated that CD4(+)CD25(+) T cells are able to influence protective immunity underlying premunition to P. berghei NK65 parasites.

Scanty congenital plasmodium parasites as a possible cause for several autoimmune diseases

Recently it was reported that 19.8% of the patients with rheumatoid factor, who had no previous history of malaria and had not visited endemic regions for at least the past five years, generated false-positive results in two rapid malaria tests that capture two different plasmodium antigens. This intriguing finding supports the hypothesis presented, suggesting systemic lupus erythematosus and possibly several other autoimmune diseases are caused by a scanty amount of persistent plasmodium parasites in the internal tissues, which provokes diverse autoantibodies production, and can be transmitted congenitally. This hypothesis suggests a comprehensive explanation for the predominance of autoimmune diseases in African populations in the West yet their infrequency in tropical Africa, and for the studies reporting that several of these diseases benefit from antimalarials. The implication of this hypothesis is that these autoimmune diseases are actually infectious, and may infect individuals who contracted malaria in the past or whose female ancestors had contracted it, and possibly blood transfusion recipients.

Autoimmunity and malaria: what are they doing together?

A common feature of autoimmunity is the presence of autoantibodies (AAb). Two types of AAb have been described: the 'pathogenic' AAb, associated with autoimmune diseases (AID), and the so-called 'natural' AAb. The latter are present in all normal individuals and have been postulated to play a major role as a first defensive barrier of the organism. Both the 'pathogenic' and the 'natural' AAb can be detected at higher frequencies among individuals exposed to viral, bacterial and parasitic infections. The malaria associated AAb do not seem to result from a generalised polyclonal B-cell activation (PBA), have specificities that may differ according to the degree of clinical immunity and do not seem to be pathogenic. Malaria may offer a protective effect against AID, by diminishing its severity or by either preventing or retarding its expression. AAb could also participate in the immune protection against malaria, and this could happen in several ways: (i) AAb directed to modified Ag expressed on the red blood cell (RBC) membrane during parasitisation and (ii) AAb reactive with crypto- or neo-Ag revealed on both normal and infected RBC membranes, by destroying infected, and also normal, erythrocytes; (iii) anti-idiotype AAb specific of the binding site of anti-merozoite Ab, which would mimic the parasite ligand for the RBC receptor, by competing with parasites and blocking RBC invasion; (iv) AAb cross-reactive with parasite material - such as nuclear or cytoskeleton Ag - having a direct parasiticide activity; (v) the natural AAb network, through its 'anti-bacterial first defense barrier'; and finally (vi) anti-phospholipid (PL) AAb, by neutralizing the pathogenic properties of parasite-derived PL. Finally, in view of currently available knowledge, it is concluded that, since AAb are not always pathogenic, the price for an 'autoimmunity-mediated' protection in malaria would not necessarily be immunopathology and clinical autoimmunity, and a protective role of AAb could be exerted with no danger to the host.

Molecular basis for evasion of host immunity and pathogenesis in malaria

The article relates the ability of the malaria parasite Plasmodium falciparum to avoid a protective immune response, and to induce pathological changes, to the properties of specific parasite molecules. Cytoadherence and rosetting are important features of cerebral malaria and involve proteins located on the surface of the infected red blood cell. Proinflammatory cytokines, particularly tumour necrosis factor (TNF), play a role in protective immunity and in inducing pathology. Glycophosphatidyl inositol membrane anchors of parasite proteins possess insulin like activity and induce TNF synthesis. People subject to repeated infections in malaria endemic areas rarely develop complete or sterile immunity to malaria. They frequently carry small numbers of parasites in the blood, with little symptoms of the disease, illustrating a phenomenon termed semi-immunity. The basis for semi-immunity is incompletely understood. Malaria parasites are susceptible to several immunological effector mechanisms. The presence of extensive repetitive regions is a feature of many P. falciparum proteins. Available evidence suggests that the structural characteristics of the repeats and their location on the surface of parasite proteins promote immunogenicity. The repeats may help the parasite evade host immunity by (i) exhibiting sequence polymorphism, (ii) preventing the normal affinity and isotype maturation of an immune response, (iii) functioning possibly as B cell superantigens, (iv) generating predominantly thymus independent antibody responses, and (v) acting as a sink for binding protective antibodies. Sequence diversity in non-repetitive regions and antigenic variation in parasite molecules located on the surface of infected red blood cells also play a role in immune evasion. Some sequence homologies between parasite and human proteins may be due to molecular mimicry. Homologies in other instances can cause autoimmune responses. The immune evasion mechanisms of the parasite need to be considered in developing vaccines. Protective immunity and pathology may be delicately balanced in malaria.

Endomyocardial fibrosis in Egypt: an illustrated review

The detailed features of right sided endomyocardial fibrosis are described in 15 out of 10,000 consecutive patients who all had infection with Schistosoma mansoni and came from rural Egypt. Laboratory investigations, 12 lead electrocardiography, chest radiography, and Doppler echocardiography were performed in all patients. Cardiac catheterisation and angiography were performed in eight. Endomyocardial biopsy specimens were obtained from the right ventricles of two patients and pericardial biopsy specimens from two. Pericardiocentesis was performed in all patients. All patients were infected with S mansoni and had schistosomal hepatic fibrosis and ascites. Eleven had splenomegaly. All patients had raised cervical venous pressure with prominent Y descent and atrial fibrillation. Eosinophilia was notably absent. Echocardiography showed apical fibrosis in the right ventricle, obliteration of the ventricle, and moderate to massive exudative pericardial effusion in all patients. Calcification and fibrosis extended into the right ventricular outflow tracts in two patients. Huge right atrial thrombi occurred in five patients. Tricuspid regurgitation (grades I-II) was detected in 11 patients by Doppler ultrasonography. Haemodynamic and angiographic data confirmed the pure right sided restrictive pathophysiology. Pericardial biopsy specimens showed perivascular inflammatory infiltrates in two patients and a schistosomal granuloma in one. Endocardial biopsy specimens showed dense fibrosis with many fibroblasts. Endomyocardial fibrosis in Egypt is unique in several aspects. It always affected only the right side of the heart. Calcification and fibrosis extended to the right ventricular outflow tract. Pericardial inflammatory reaction was present. The relation to schistosomiasis and the link to periportal hepatic fibrosis in these patients is intriguing.

Tropical rheumatology. Immunological aspects

The presence of auto-antibodies in infectious diseases continues to puzzle and provoke. It is hoped that sequencing studies in particular will yield further clues as to the role and mechanism of production of autoantibodies in infectious diseases. This, in turn, may also provide further insights into the role of auto-antibodies in auto-immune diseases. From a practical clinical viewpoint, the search for improved auto-antibody tests and new diagnostic markers with improved sensitivity and specificity must continue in the tropics. Until this is achieved, the results of auto-antibody tests in persons living in the tropics, persons from the tropics or patients with tropical infections, must be interpreted with caution.

Autoantibodies in malaria, tuberculosis and hepatitis B in a west African population

Following reports of associations between autoantibodies and living in the tropics, we have studied the seroprevalence and nature of anti-nuclear antibodies, anti-cardiolipin antibodies, antibodies to extractable nuclear antigens and anti-neutrophilic cytoplasmic antibodies in 351 West Africans with malaria, tuberculosis or hepatitis B, or in good health. Amongst healthy West Africans we found a seroprevalence of 7% for anti-nuclear antibodies with several staining patterns, and of 30.3% for anti-cardiolipin antibodies. Among patients with tuberculosis and malaria there was twice that frequency of anti-nuclear antibodies (predominantly speckled in pattern), and anti-neutrophil cytoplasmic antibodies (predominantly IgM) were demonstrated in a few cases. A possible association between IgG anti-cardiolipin antibodies and tuberculosis was observed (P < 0.05), but antibodies to double-stranded DNA were not elevated and no antibodies to extractable nuclear antigens were found in any of the patients or healthy individuals studied. Our findings suggest the need for caution in the interpretation of autoantibody tests in subjects from or living in the tropics, as well as in patients with tropical infections.

Rheumatoid factor and rheumatoid factor isotypes in loiasis with and without accompanying glomerulonephritis

We have studied the distribution of rheumatoid factor isotypes amongst patients with loiasis with and without accompanying glomerulonephritis to determine the possible role of rheumatoid factor antiglobulins in this disease. Our findings indicate an increase in both immunoglobulin (Ig) G and IgM rheumatoid factor isotypes in patients with filariasis alone as well as in patients with accompanying glomerulonephritis. No association with IgA rheumatoid factor was found. The raised IgG and IgM rheumatoid factor levels did not correlate with corresponding IgG and IgM levels.

Parasitic infection and autoimmunity

The studies summarized in this paper indicate that parasitic infections can serve as a trigger factor of autoimmune reactivity by several mechanisms. The relationship between parasites and autoimmunity could be manifested by the presence of autoantibodies or T-cells with autoreactivity. In spite of the evidence that has accumulated, the specific association between infection and autoimmunity is still obscure. The reasons for tissue damage in parasitic diseases are controversial. Some believe it is the result of pathogenic autoantibodies or autoreactive T-cells. Others argue against the causative role of autoimmunity in the formation of tissue lesions. The parasite itself could be the cause of tissue destruction, thus releasing high amounts of self antigens which might stimulate the autoreactivity. There is now little doubt that some degree parasite/host cross-reactivity occurs, and definition of cross-reacting antigens and epitopes is now taking place. It seems likely that a combination of events could result in cross-reactivity including: parasites themselves have cross reactive molecules and altered self antigens by adsorbing of parasite material to surrounding host cells. The mechanisms involved in parasites autoimmunity are complex and numerous, requiring a rigorous experimental approach to rationalize each step and determine its clinical importance. The developed methods in immunochemistry, monoclonal antibodies and hybridoma technology, and recombinant DNA research not only facilitate this kind of approach but also allow optimism for a successful outcome.

Mitogenic activity of soluble preparations from Plasmodium berghei-infected erythrocytes to L3T4+, Lyt2- and L3T4-, Lyt2+ T-cell subsets

The mitogenic activity of soluble preparations of Plasmodium berghei-infected erythrocytes (PBEP) in cultures of T or non-T cells isolated from spleens of naive mice was investigated. The proportion of cells at each phase in the cell cycle was examined by flow cytometry after incubation with various concentrations of PBEP; the proliferation index (PI-cell numbers at S, G2 and M phases/cell numbers at all phases x 100) was calculated. An addition of PBEP led to significant increases in the PI levels of T cells, but not in those of non-T cells. Moreover, when PBEP were added to L3T4+, Lyt2- (helper) or L3T4-, Lyt2+ (suppressor) T-cell fractions separated from rosette-forming T cells in spleens, significant increases in PI levels were detectable in both helper and suppressor T-cell cultures. These results indicate that PBEP have a mitogenic activity directed to both helper and suppressor T-cell fractions isolated from spleens of naive mice and that PBEP or Plasmodium parasites may in this way induce complicated immune responses during malaria infection.

Autoantibodies and tropical infections

Autoantibodies against diverse autoantigens have long been known to exist in the sera of several tropical infections. The introduction of monoclonal antibody technology has allowed immortalization of autoantibody secreting B-lymphocytes and subsequent analysis of these autoantibodies. This paper discusses the current literature on the induction, origins, significance and analysis of autoantibodies.

A heat shock-like protein from the human malaria parasite Plasmodium falciparum induces autoantibodies

The humoral immune response to a 72-kDa heat shock-like protein of Plasmodium falciparum has been analyzed using mouse monoclonal antibodies (mAb) and human immune sera. Three regions of the molecule containing B cell epitopes were identified by screening a sublibrary encoding the COOH-terminal half of the antigen with the mAb. One B cell epitope mapped to a region poorly conserved between the parasite 72-kDa polypeptide and mammalian heat-shock proteins (Hsp 70). Another mAb, G10C9, reacted with an amino acid region that has a high degree of homology with mouse (87.5%) and human (81.2%) Hsp 70. Both mouse and human cells were recognized by this mAb when analyzed by indirect immunofluorescence and by two-dimensional immunoblots. Sera from humans infected with malaria also recognized the human Hsp 70. Thus, our results indicate that autoantibodies directed against host Hsp 70 can be induced by the homologous parasite protein.

Suppression of malaria-induced autoimmunity by immunization with cryoglobulins

Cryoglobulins obtained from malaria-infected (Plasmodium berghei berghei) Balb/c mice were administered intraperitoneally to naive Balb/c mice. Ten days or 9 months following cryoglobulin administration, the naive mice were infected with malaria. Comparison of sera from cryoglobulin-treated malaria-infected mice with sera from control infected mice revealed that pretreatment with cryoglobulins resulted in (1) reduced levels of circulating immune complexes; (2) reduced levels of autoantibodies reactive with nuclear and cytoplasmic antigens; and (3) suppressed development of cryoglobulinemia. Furthermore, the effect of cryoglobulins was long lasting, suggesting that recipient mice may have been actively immunized against autoantibody production.

Anemia and anti-erythrocyte antibodies developed after repeated injections of sonicated preparations of Plasmodium berghei and Babesia rodhaini

Anemia developed in mice after repeated injections of sonicated preparations of Plasmodium berghei and Babesia rodhaini. Anti-erythrocyte antibodies were detected in sera by an enzyme-linked immunosorbent assay and their levels rose as anemia developed. Administration of carbon particle suspension to block the mononuclear phagocyte system was effective to inhibit anemia induced by injections of sonicated parasite preparations. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting analyses were carried out to examine autoantigens on the surface of the erythrocyte membrane reacting to anti-erythrocyte antibodies. The anti-erythrocyte antibodies from mice injected with the sonicated P. berghei preparations bound specifically to three components of the erythrocyte membrane. The anti-erythrocyte antibodies produced by the sonicated B. rodhaini preparations also reacted with four components, two of which corresponded to those reacting after the injection of the sonicated P. berghei preparations. These results suggest that both P. berghei and B. rodhaini organisms have some materials capable of inducing production of the anti-erythrocyte antibodies which mediate erythrophagocytosis by macrophages of the mononuclear phagocyte system during Plasmodium and Babesia infections.

Specificity of routine parasite serological tests in autoimmune disorders, neoplastic disease, EBV-induced mononucleosis, and HIV infection

Sera from 120 patients with rheumatological disorders, neoplastic disease, infectious mononucleosis, and HIV infection, and from 30 healthy blood donors were tested for nonspecific reactivity in 13 routinely used parasite serological tests. Responses were detected in 3/30 healthy blood donors (10%) vs 25/120 patients (21%). Of 40 responses in these 28 responders most were weakly reactive, and 25 out of 40 responses were only at borderline level. Response rates were highest in patients with mononucleosis presumably due to heterophile antibodies. Only four patients had responses in at least two different serodiagnostic tests for the same parasitic infection. Response patterns indicative of a possible underlying, concurring, or superimposed parasitic infection, thus, were rare. Especially susceptible to nonspecific reactivity seemed to be immunofluorescent antibody tests for filariasis, schistosomiasis, and amebiasis. In conclusion, compared to healthy controls, false-positive serological responses seem to be more frequent in certain disease groups dependent on the test methods used. Second, the use of more than one serodiagnostic test for the same parasitic disease will substantially facilitate the identification of nonspecific reactivity. Third, for better defining the specificity of parasitological serodiagnosis, more studies should include control sera from patients with nonparasitic diseases that frequently show immunological abnormalities.

Severe megaloblastic anaemia due to vitamin B12 deficiency in The Gambia

Five cases of severe megaloblastic anaemia in Gambians are described. Three of the patients were found to have pernicious anaemia. The difficulties in diagnosis and the various features of pernicious anaemia in Negroes are discussed. A brief review of the literature is included.

Stimulation of autoantibody production in normal blood lymphocytes by malaria culture supernatants

Supernatants from Plasmodium falciparum cultures containing soluble parasite material were mitogenic for normal human peripheral blood mononuclear cells (MNC) in vitro. This was evidenced by blast transformation and significant incorporation of 3H-thymidine and confirms earlier reports of the mitogenic potential of malaria parasites. Lymphocyte activation by these malaria derived products was polyclonal as demonstrated by increased secretion of IgA, IgG and IgM by the stimulated cells. Using rat tissues and Hep-2 cells as substrates, autoantibody activity was found in the IgM fraction of the secreted immunoglobulin. Speckled anti-nuclear (ANA) antibody, anti-globulins (rheumatoid factor) and anti-intermediate filament antibodies were produced by the stimulated lymphocytes. No significant immunoglobulin secretion with autoantibody specificity was found in control cultures in which normal MNC were incubated with supernatants from non-parasitized red cell cultures. The data supports the suggestion that polyclonal lymphocyte activation by parasite derived products occurs in vivo and, in addition, provides an explanation for the presence of autoantibodies in the serum of malaria patients.

Deficiency of Con A-induced suppressor cell activity in peripheral blood mononuclear cells from Thai adults naturally infected with Plasmodium falciparum and Plasmodium vivax

Con A-pretreated mononuclear (MNC) cells from Thai adults with naturally acquired P. falciparum or P. vivax malaria were significantly less effective in suppressing the responsiveness of autologous or normal allogeneic responder cells to mitogenic lectins or allogenic stimulator cells than pretreated cells from healthy donors. Serial studies of three patients demonstrated that reduced suppressor cell activity was present early in malaria infection but returned to normal soon after treatment. These studies demonstrate that the loss of T cells previously observed in patients with malaria, in part may functionally represent a loss of suppressor T cells.

Specificity of auto-antibodies in malaria and the role of polyclonal activation

Sera of 173 individuals living in a malaria endemic region in Upper Volta (Donsé village) were screened for the presence of 14 auto-antibodies by the indirect immunofluorescent and/or passive haemagglutination techniques. At least one auto-antibody (AAb) was detected in sera of 72% (124 out of 173) subjects. No differences in the AAb frequency was observed in the sex or age groups. Conversely, a significant relationship between a high frequency of auto-antibodies, high malaria antibody titres and high IgM levels was observed. Antinuclear antibodies (ANA) (87% of total AAb) and particularly those of speckled pattern of fluorescence were by far the most frequently observed. Smooth muscle antibodies (SMA), heart and gastric parietal cell antibodies and thyroglobulin antibodies were found at a normal frequency. This selective increase in the frequency of one AAb (and not of others) cannot, in our opinion, result from a non-specific polyclonal activation. An alternative hypothesis involving both a specific antigenic and a non-specific mitogenic signal is proposed.

Massive splenomegaly in Northern Zambia. I. Analysis of 344 cases

Massive splenomegaly is common in Northern Zambia. Nearly 40% of 344 patients were diagnosed as Tropical Splenomegaly Syndrome of malarial origin. Portal hypertension, lymphoreticular and haemopoietic malignancies, and schistosomiasis accounted for another 46%. The common causes of splenomegaly show differences of frequency within Zambia and also between Zambia and other African countries.

Implications of heterophile antigens in immunological infertility in males

Immunological study was conducted on serum and hydrocel fluids from males belonging to an equatorial African population heavily contaiminated by Filaria and Schistosoma. Anti-spermatozoa antibodies were detected by agglutination in 31 of 64 sera and 24 of 60 fluids, and by cytotoxicity in 19 of 64 sera and 8 of 60 fluids. Antinuclear antibodies were detected in 21 of 64 sera and 8 of 60 fluids. However, the titers of these antibodies were low, as were the frequency and titers of other tissues antibodies. The appearance of antispermatozoa antibodies is also correlated with extensive skin burns and infection by Pseudomonas aeruginosa or severe Candidiasis.

Pancarditis with valvulitis in endomyocardial fibrosis (=emf) and in human African trypanosomiasis (= hat). A comparative histological study of four Ugandan cases

The study compares the histotopographical lesions of two cases of endomyocardial fibrosis with those of two hearts in sleeping sickness, all of them from Uganda. There was considerable overlapping of the fibrosed zones in endomyocardial fibrosis and the corresponding sites occupied by the chronic inflammatory process in trypanosomiasis. There was a tendency towards fibrosis in the hearts of trypanosomiasis while, in endomyocardial fibrosis, there were mild focal chronic cellular infiltrations. This overlapping and to some extent similarities would suggest that the two conditions may only differ in evolution in time and intensity and that they may be the result of the same inflammatory process. Stipulating a cardiac tropism for African trypanosomes, it is suggested that some African cases of endomyocardial fibrosis may be merely burnt-out lesions of trypanosomal pancarditis. Previous descriptions of carditis in human African and American trypanosomiasis are briefly reviewed, and the present findings are discussed in view of a possible trypanosomal aetiology in some African cardiomyopathies.

Endomyocardial fibrosis and eosinophilia

Absolute eosinophil counts were assessed in 15 African patients with proven endomyocardial fibrosis. Though the mean eosinophil count in patients with endomyocardial fibrosis was higher compared with the normals reported from Kampala (1-13 vs 0.72X10(9)/1), the absolute range was comparable. A high percentage of patients with endomyocardial fibrosis had malarial parasites, high malarial antibody titres, hookworms, or strongyloides, but the correlation of eosinophilia to various parasitic infections was poor. Both eosinophilia and parasitic infections are common in the tropics and they effect patients with endomyocardial fibrosis no more than the population at large. Other aetiological factors, genetic, environmental, and immunological, are felt to be important in the causation of endomyocardial fibrosis in Uganda and evidence for this is reviewed. Though there is a similarity in pathological features, African endomyocardial fibrosis is a distinct entity from Löffler's endocarditis and cardiac lesions seen in eosinophilic leukaemia or reactive eosinophilia. There is no hard evidence to suggest that African endomyocardial fibrosis is a variant of Löffler's endocarditis caused by parasitic infections via eosinophilia.

Characteristics of African blood

Genetic markers in people of African ancestry and tables comparing Africans and Europeans are compiled to illustrate the blood differences. The existence of the African genetic characters, R0 (cDe), D-u and Ee (e-s, ce-s) in an Rh-Hr system are discussed. The high incidence of R0 (81.9%) in Africans is evident. Studies of ABO and the sickle cell trait in East Africa reveal the African tribes responsible for the original populating of Africa. The pygmoids of Uganda and Zaire, the Nilotes of West Nile, and the Bantu of Uganda are possibly responsible. Subgroups of A antigen in Africans and Europeans are compared, and their differences are outlined. These antigens appear to be different in the two races, and a reliable method for grouping A1 and A2 in Africans is described. For convenience, A2, Aint., Abantu, and other subgroups of A in Africans are renamed "non-A1." Attention to these subgroups on African paternity studies is emphasized. African problems in MNSs, Duffy, P, Lewis, and Sutter are presented. Immunoglobulines, Rh(D) immunization, enzyme autoantibodies, and a technique to detect them are discussed and described in detail. Studies on tropical splenomegaly syndrome show that it is an immune complex disease. Fluctuation titers of ABO iso-antibodies are observed to vary more strikingly in Africans than in Europeans. This is offered as a possible explanation of the high incidence of ABO hemolytic disease of the newborn in Africans.

Antiglobulins in Nigerians with rheumatoid disease

The levels of IgG and IgM antiglobulins in the sera of Nigerian patients with seropositive rheumatoid arthritis, seronegative arthritis, and Reiter's syndrome have been studied using an immunosorbent of glutaraldehyde insolubilized human IgG. No conclusion could be reached in the case of IgM antiglobulins because of the relatively high threshold of detectability in the quantitation procedure, but all groups of patients had significantly higher levels of IgG antiglobulins than did a group of healthy Nigerians.