The immunopathology of actinomycetoma lesions caused by Streptomyces somaliensis

The immune responses in actinomycetoma lesions caused by Streptomyces somaliensis in Sudan were characterized by immunohistochemistry during 1997-1998. In sections stained with haematoxylin and eosin, the inflammatory reaction around the grain was of 2 types. In type I there were 3 zones: a neutrophil zone immediately around the grain, an intermediate zone containing mainly macrophages, and a peripheral zone consisting of lymphocytes and plasma cells. Zone 1 stained positively for CD15 (neutrophils), zone 2 for CD68 (macrophages) and CD3 (T lymphocytes), and zone 3 for CD20 (B lymphocytes). In the type II reaction, there was no neutrophil zone, the grains being surrounded only by macrophages and giant cells. This was confirmed by immunohistochemistry, which demonstrated the presence of CD3 positive cells. Immunoglobulins G and M and complement were demonstrated on the surface of the grain and on filaments inside the grain. Neutrophils and macrophages were recruited into the lesion by complement and were involved in the fragmentation of the grain. The cytokine profile in the lesion and regional lymph nodes was of a dominant Th2 pattern (interleukins-10 and 4).

Serological and virological characterization of clinically diagnosed cases of measles in suburban Khartoum

Measles continues to be a major childhood disease in terms of global morbidity and mortality. In the main areas of its endemicity the only available means of diagnosis are based on clinical criteria: the presence of a maculopapular rash and fever accompanied by cough, coryza, and/or conjunctivitis. We have studied 38 clinically diagnosed cases of measles in Khartoum, Sudan, by means of serology, reverse transcriptase PCR (RT-PCR) on throat swabs and virus isolation from lymphocytes. On the basis of serology, 28 patients were diagnosed as having an acute measles virus (MV) infection, while in 10 cases the clinical symptoms proved to have other causes. It was shown that in cases with low serum immunoglobulin M (IgM) levels, an additional measurement of IgG or virus-neutralizing antibodies was necessary to discriminate between patients with an acute MV infection sampled during an early stage of the disease and patients who had experienced an MV infection in the more distant past. The serological laboratory diagnosis was validated by an MV-specific RT-PCR: for all confirmed measles cases tested a fragment of the correct size which hybridized with a third MV-specific primer could be amplified, while all serologically negative cases were also RT-PCR negative. MV could be isolated from 17 out of 23 of the serologically confirmed cases, demonstrating that virus isolation is less reliable as a diagnostic tool than serology or RT-PCR. This study stresses the urgent need for a rapid diagnostic field test for measles.

Characterization of the local and systemic immune responses in patients with cutaneous leishmaniasis due to Leishmania major

In this study skin biopsies and peripheral blood samples were obtained from patients with cutaneous leishmaniasis caused by Leishmania major. Samples were obtained at diagnosis and during healing when the lesions had regressed to half the original size. At diagnosis most of the cells expressed HLA-DR. The numbers of CD8+ cells in the lesions were higher at diagnosis than during healing. By contrast, a lower percentage of PBMC expressed CD8+ cells at diagnosis probably due to sequestration in the lesion. In the lesion, in situ staining for IFN-gamma, IL-10, and IL-4 showed marked variation between all patients in the number of positive cells for a particular cytokine. The proliferative response of PBMC to leishmanial antigens and IFN-gamma production tended to increase during healing. Cytokine patterns in the PBMC in response to Leishmania antigen was more specific than in the lesion and correlated better with the clinical manifestations. Possible reasons for this are discussed.

Serodiagnosis of Leishmania donovani infections: assessment of enzyme-linked immunosorbent assays using recombinant L. donovani gene B protein (GBP) and a peptide sequence of L. donovani GBP

The repetitive sequence of Leishmania major gene B protein (GBP) has previously been shown to be a useful tool in the diagnosis of cutaneous leishmaniasis (CL). Here, we have assessed enzyme-linked immunosorbent assays (ELISAs) using recombinant L. donovani GBP (rGBP) and a peptide sequence of L. donovani GBP (GBPP) in the diagnosis of L. donovani infections in Sudan. The sensitivity of the rGBP ELISA in diagnosing visceral leishmaniasis (VL) and post kala-azar dermal leishmaniasis (PKDL) was 92% and 93%, respectively. In contrast, the sensitivity of the GBPP ELISA was 55% for VL and 63% for PKDL. Plasma antibody reactivity of donors with VL and PKDL remained high for an extended period after the end of treatment. Antibody-reactivity to rGBP and GBPP was detected in 71% and 14% of plasma samples from CL patients, respectively. Plasma from healthy Sudanese donors living in an area endemic for malaria but free of leishmaniasis was negative in both assays.

Post kala-azar ocular leishmaniasis

The clinical features, diagnosis and treatment of 6 patients with post kala-azar ocular leishmaniasis are described. The eye lesions were associated with past or concomitant post kala-azar dermal leishmaniasis (PKDL). Four patients had post kala-azar leishmanial conjunctivitis and blepharitis. Using the polymerase chain reaction, the causative parasite was characterized as Leishmania donovani in 2 of these 4 patients. Two patients had post kala-azar anterior uveitis. The diagnosis of uveitis was based on the clinical manifestations, temporal relation to treated visceral leishmaniasis, the association with PKDL and positive anti-Leishmania serology. All patients were treated with systemic sodium stibogluconate. Patients with anterior uveitis were also treated with steroid and atropine eyedrops. The response to treatment was good. The importance of early diagnosis and treatment of ocular leishmaniasis is stressed.

Treatment of visceral leishmaniasis with sodium stibogluconate in Sudan: management of those who do not respond

Almost all (98%) of 1593 visceral leishmaniasis (VL) patients treated with sodium stibogluconate (Pentostam; Wellcome) in Sudan between 1989 and 1995 and follow-up responded well to treatment. However, the other 33 patients, all of whom were seronegative for HIV, showed partial or no response. The two main causes of unresponsiveness were primary drug resistance (39.3%) and low drug dosages given at peripheral dispensaries (30.3%). All of those who had been sub-optimal doses were cured when adequate doses of the drug were given. A third cause was concurrent disease, particularly pulmonary tuberculosis (18%). With treatment of the concurrent disease, patients responded well to Pentostam. Eight patients who failed to respond to repeated courses of Pentostam did not benefit from pentamidine or sterol inhibitors. Three of these patients responded to liposomal amphotericin B, two responded to splenectomy in association with Pentostam therapy, and three died. Pentostam, given in adequate doses, still appears to be the drug of choice for the treatment of VL in the Sudan Liposomal amphotericin B is a suitable second-line drug.

Decreased erythropoietin response in Plasmodium falciparum malaria-associated anaemia

One of the most serious manifestations of Plasmodium falciparum malaria is anaemia. Its established causes are increased red cell destruction and ineffective erythropoiesis. Since proinflammatory cytokines have been shown to suppress the in vitro synthesis of erythropoietin (Epo), we measured serum immunoreactive Epo in 90 Sudanese patients suffering from malaria. Even in severe cases of anaemia (blood haemoglobin < 80 g/l), serum Epo levels rarely exceeded 300 U/l. For comparison, serum Epo was increased up to 12,000 U/l in a reference group of Caucasian patients with anaemia not associated with infection. Moreover, the slope of the log Epo/haemoglobin regression line was less steep in malarial anaemia. Thus, as documented for other chronic inflammatory disorders, there is a relative lack of Epo in malaria-associated anaemia. Treatment with the antimalarial drug chloroquine may aggravate the defect in Epo production, because chloroquine inhibited Epo synthesis when tested in cell culture.

Detection and characterization of Leishmania in tissues of patients with post kala-azar dermal leishmaniasis using a specific monoclonal antibody

Sections from skin lesions and draining lymph nodes of patients with post kala-azar dermal leishmaniasis were examined using an immunoperoxidase method and a monoclonal antibody directed against Leishmania donovani. Parasites were detected in 22 of 25 biopsies (88%). In parallel sections stained by haematoxylin and eosin, parasites were detected in only 5 of 25 of the biopsies (20%). The demonstration of whole parasites or parasite antigen is diagnostic.

Blood supply and vasculature of mycetoma

The blood supply to the mycetoma lesion and its vasculature were studied in patients with various types of mycetoma using histological, ultrastructural, angiographic and sonographic techniques. The mycetoma lesion proved to be well vascularized. However, certain vascular abnormalities were demonstrated. In histological sections, the small arteries and arterioles showed medial muscular hypertrophy in 83%, intimal fibrosis in 33%, arteritis in 7% and endarteritis obliterans with narrowed lumen in 7% of the patients. No vascular occlusion, ischaemic changes or arteriovenous shunts were observed. These changes were confirmed ultrastructurally. Angiography of the lesion showed a brisk pathological circulation which was more evident in eumycetoma. The vascular Doppler study showed normal blood flow pattern in the affected limb. Regional intra-arterial chemotherapy for mycetoma is suggested as a possible treatment modality.

Oronasal leishmaniasis caused by a parasite with an unusual isoenzyme profile

A 45-year-old Sudanese man from western Sudan presented with oronasal leishmaniasis of three years duration. He had no history of previous kala-azar or cutaneous leishmaniasis. The parasite isolated from the oral mucosa was characterized by isoenzymes using 12 enzymes and by polymerase chain reaction amplification of kinetoplast DNA using species-specific primers. The specific primers gave products indistinguishable from those of the Leishmania donovani complex. However, the isoenzyme profile showed a zymodeme pattern that was significantly different from the zymodemes previously reported in the Sudan and the Ethiopian region.

The Marrara syndrome: a hypersensitivity reaction of the upper respiratory tract and buccopharyngeal mucosa to nymphs of Linguatula serrata

The Marrara syndrome, like Halazoun in Lebanon, is a hypersensitivity reaction of the upper respiratory tract and buccopharyngeal mucosa to nymphs of Linguatula serrata. The condition follows the consumption of Marrara which consists of raw liver, lungs, trachea and rumen of goats and sheep infected with larvae of L. serrata. The adult worm is found in the nasal passages of dogs. Sheep and goats are infected by eggs from infected dogs. A survey that included 240 adult individuals in a village of endemic L. serrata infection in the Sudan showed that 20% experienced symptoms of allergic nasopharyngitis (Marrara syndrome) following the consumption of raw viscera of goats or sheep at least once in their life. In a prospective study of 24 patients who reported to hospital with the Marrara syndrome, the clinical features included itching in the throat and nose, unilateral conductive deafness, tinnitus and facial palsy. Secondary bacterial infection caused suppurative otitis media. Adult L. serrata parasites were found in the nasal passages of 56 and 47% of male and female dogs in the endemic area. Nymphs were recovered from the mesenteric lymph nodes, lungs and livers of goats in the area.

The pathology of cutaneous leishmaniasis in the Sudan: a comparison with that in other geographical areas

The pathology of cutaneous leishmaniasis (CL) caused by Leishmania major zymodeme LON 1 in the Sudan was compared with that caused by L. major zymodeme LON 4 in Saudi Arabia and with that already described for L. tropica infections in Iran and for localized CL in the New World. The lesions were classified according to Ridley's five histological types. Most of the lesions in the Sudan and Saudi Arabia were of types B and C, characterized, respectively, by diffuse macrophage necrosis and focalized necrosis. B was the most common type in Nicaragua and Guyana whereas responses of types A (in which there are heavily parasitized macrophages without necrosis) and D (reactive tuberculoid) were the most frequent in Iran. The type-E response, which is similar to D but with virtual absence of plasma cells, was uncommon in all areas. The type-D reaction is a chronic relapsing disease when associated with L. tropica but not when associated with L. major. The major differences in the pathology of CL in different geographical areas most probably relate to differences in the Leishmania species involved. Minor differences, however, not only occur between patients from the same area but may also occur, with time, in the same patient. Detailed comparison between areas is therefore difficult; lesions on one patient may heal asynchronously and show different histological types at any point in time and rebiopsy from the same lesion during healing reveals changes from one histological type to another.

Internal fistula formation: an unusual complication of mycetoma

This paper reports 2 hitherto undescribed complications of mycetoma, urinary extravasation and expectoration of mycetoma grains due to cutaneo-urethral and cutaneo-pleuro-bronchial fistulae, respectively. The first patient had an infection with Actinomadura madurae which started in the foot and had spread progressively to involve the whole limb, anterior abdominal wall, perineum and urethra. The second patient had Madurella mycetomatis infection of the hand and, in spite of extensive treatment, the infection had spread to the axilla, chest wall, lung and bronchial tree. Both patients died of the sequelae of these complications. The pathogenesis of these unusual complications is discussed.

Necrotizing and suppurative lymphadenitis in Leishmania major infections

The pathology of lymph nodes and subcutaneous nodules in 6 patients with cutaneous leishmaniasis (Oriental sore) due to Leishmania major is described in this paper. In 3 patients enlarged epitrochlear lymph nodes were found to be associated with primary skin lesions in the forearm. The lymph node in one patient showed a necrotizing granulomatous reaction that simulated tuberculous lymphadenitis. Leishmania parasites were, however, found in sections of the node, and staining for mycobacteria was negative. The second patient presented with an abscess and a discharging sinus in the epitrochlear region. Parasites were found in smears of the pus and cultures for bacteria were negative. The lesion healed with antimonial therapy. In the third patient the lesion resembled cat-scratch disease and showed stellate abscesses and granulomas. Leishmania parasites were also identified in the sections. Sections of a subcutaneous nodule from the fourth patient showed a necrotizing granuloma. The lesion healed spontaneously and the patient became leishmanin-positive. In two other patients fine needle aspiration of the subcutaneous nodules showed parasites, granuloma and necrosis. We concluded that L. major disseminates from the primary cutaneous lesion via the lymphatics to the subcutaneous tissues and the regional lymph nodes. The subcutaneous nodules and lymphadenopathy may persist long after the primary lesion had healed. The primary lesion is sometimes inconspicuous. Necrotizing and suppurative lymphadenitis due to L. major have to be distinguished from other causes of necrosis and suppuration such as tuberculosis and cat-scratch disease.

Diversity among Leishmania isolates from the Sudan: isoenzyme homogeneity of L. donovani versus heterogeneity of L. major

Leishmania isolates from patients in the Sudan suffering from either visceral or cutaneous leishmaniasis were characterized using a battery of 12 enzymes. Aspartate aminotransferase separated the L. donovani isolates into 2 distinct zymodemes, but the overall results showed no significant geographical variation among L. donovani isolates. In contrast, the isolates of L. major were polymorphic, exhibiting differences in nucleoside hydrolase, 6-phosphogluconate dehydrogenase, superoxide dismutase, esterase, mannose phosphate isomerase, and aspartate aminotransferase, resulting in the description of 4 new enzymatic variants.

The pathology of cutaneous leishmaniasis due to Leishmania major in Sudan

The pathology of cutaneous leishmaniasis in Sudan, where the disease is caused by Leishmania major, was studied by light and electron microscopy. Lesions were classified into four distinct groups based on the ratio of different cell types, especially lymphocytes, macrophages, and plasma cells in the inflammatory infiltrate, and the formation of compact epithelioid granulomas or the presence of necrosis. In the lesions, there was a positive correlation between the number of lymphocytes and the number of activated macrophages and epithelioid cells. We suggest that the parasites are eliminated from the lesion by two processes: 1) a lytic mechanism in which parasites are lysed within activated macrophages and 2) necrosis of parasitized macrophages. Morphologic evidence for these two mechanisms of parasite elimination was detected by both light and electron microscopy. The evolution of the pathology of the lesions was followed by rebiopsy when the lesion had regressed in size under antileishmanial therapy.

Dichotomy of the T cell response to Leishmania antigens in patients suffering from cutaneous leishmaniasis; absence or scarcity of Th1 activity is associated with severe infections

The T cell response was studied in 25 patients suffering from cutaneous leishmaniasis caused by Leishmania major with severe (n = 10) and mild (n = 15) disease manifestations. Peripheral blood mononuclear cells (PBMC) from the patients were activated by sonicates of Leishmania promastigotes (LMP) and amastigotes (LDA), and the surface protease gp63. The proliferative responses to Leishmania antigens were lower in patients with severe disease than in patients with mild disease (P = 0.01-0.05), and such a difference was not observed in the response to purified protein derivative of tuberculin (PPD) or tetanus toxoid (TT). LMP-induced interferon-gamma (IFN-gamma) production was lower in patients with severe than in patients with mild disease (P < 0.05). When the IL-4 and IFN-gamma responses of each patient were considered, two response patterns were observed in the cultures activated by the Leishmania sonicates. One response pattern was characterized by high production of IFN-gamma without production of IL-4 (a Th1-like pattern), the other was characterized by low IFN-gamma levels which in most cases were associated with IL-4 production (not a Th1-like pattern). These patterns could not be distinguished when the cells from the same donors were stimulated by TT and PPD. The percentages of patients with a Th1-like response pattern after stimulation by LMP in patients with severe and mild disease manifestations were 30% and 80%, respectively. This difference was statistically significant (P = 0.034).

The host tissue reaction to Madurella mycetomatis: new classification

In this prospective study, three types of tissue reaction to mycetoma grains are described. Type I reaction is characterized by the adherence of neutrophils to the surface of the grain leading to its disintegration. In Type II reaction, the fragmented grain and the dead neutrophils are cleared by macrophages and multinucleated giant cells, while in Type III reaction there is a discrete well developed epithelioid granuloma with Langhans's giant cells. The three types of reaction are usually seen in different combinations in the same lesion.

Sporotrichoid cutaneous leishmaniasis due to Leishmania major of different zymodemes in the Sudan and Saudi Arabia: a comparative study

Sporotrichoid cutaneous leishmaniasis is due to dissemination of amastigotes via the lymphatics to the subcutaneous tissues. A comparison was made between the potential to disseminate by this route of 2 parasites of different zymodemes in Sudan and Saudi Arabia. In Sudan cutaneous leishmaniasis is caused by Leishmania major zymodeme LON-1, and in Saudi Arabia by L. major LON-4. Sporotrichoid leishmaniasis was significantly more common in Sudan, occurring in 23% of patients compared with 10% in Saudi Arabia. Lymph node involvement was slightly more prevalent in the Sudan. Clinical and pathological differences between subcutaneous nodules, particularly when they ulcerate, and multiple primary cutaneous lesions are described and treatment of localized and sporotrichoid leishmaniasis is discussed. The pathological features of the primary lesions in the Sudan and Saudi Arabia were similar.

Liver morphology and function in visceral leishmaniasis (Kala-azar)

AIM

To study the morphology and function of the liver in visceral leishmaniasis (Kala-azar).

METHODS

Percutaneous liver biopsy specimens from 18 patients with confirmed visceral leishmaniasis were examined under light and electron microscopy before and after treatment with pentovalent antimony. The tissue was also examined for hepatitis B surface and core antigens using immunoperoxidase staining. Liver function was investigated in nine patients before and after treatment.

RESULTS

Specimens before treatment showed Kupffer cells and macrophages colonised by leishmania parasites in 40% of cases. A chronic mononuclear cell infiltrate had affected the portal tracts and lobules. Ballooning degeneration of the hepatocytes, fibrosis of the terminal hepatic venules, and pericellular fibrosis were common findings. The fibrosis was related to Ito cells transforming to fibroblast-like cells. None of the patients had hepatitis B infection. All patients had biochemical evidence of liver dysfunction before treatment. Liver function improved after treatment.

CONCLUSION

Visceral leishmaniasis causes morphological and functional disturbance in the liver. Focal fibrosis rather than cirrhosis occurs. The exact aetiology of hepatic damage is unclear but may have an immunological basis.

Cholecystectomy with and without drainage: a prospective randomised study

The use of subhepatic intraperitoneal drains was prospectively studied in 100 patients who underwent elective cholecystectomy for symptomatic gallstones. These patients were randomised to have subhepatic drains (group A, n = 50 patients) or to have no drains (group B, n = 50 patients). There was no difference in the age or sex composition of the two groups. The patients were followed in the post-operative period (0-7 days) for evidence of fever, wound infection, septicaemia and any evidence of intra-peritoneal bile leakage. Also post operative hospital stay of patients was noted. In group A, 14 patients (28%) developed spikes of temperature of 38 degrees C or more while only 5 patients (10%) in group B developed such episodes. The difference was statistically significant between the two groups (P < 0.05). Wound infection occurred significantly more (P < 0.05) in group A (in 15 patients) as compared to group B (in 5 patients). Septicaemia occurred in 2 patients in group A and in none in group B. There was no evidence of intraperitoneal bile leakage in either group. Patients in group A tended to have longer post operative hospital stay (mean of 10.2 days) than patients in group B (mean 8.7 days); but the difference between the two groups in this respect was not significant. We conclude that subhepatic intra-peritoneal drains offered no additional advantage in elective cholecystectomy. The evidence we had pointed to their harmful effects.

Distinguishing post-kala-azar dermal leishmaniasis from leprosy: experience in the Sudan

In this study 4 patients were post-kala-azar dermal leishmaniasis (PKDL), whose lesions were similar to those of lepromatous and borderline leprosy, are described. In 2 patients there was no previous history of kala-azar but they were residents of an area of known endemic kala-azar. Lack of proper clinical and laboratory assessment was behind the failure to diagnose PKDL. Consequently the patients were treated with antileprosy drugs without proof of leprosy. The 3rd and 4th patients, though suspected clinically of leprosy, were correctly diagnosed as PKDL with adequate history, clinical assessment and appropriate laboratory investigations. The salient points in distinguishing PKDL from leprosy are described and discussed.

Oral leishmaniasis associated with kala-azar. A case report

Mucosal leishmaniasis as an oral disease in the form of chronic periodontitis with involvement of the oral mucosa is described. Leishmania parasites were isolated from the oral lesions, lymph nodes, and bone marrow. The patient had a low-grade fever and hepatosplenomegaly that regressed along with the oral lesions after treatment with stibogluconate sodium.

Post kala-azar dermal leishmaniasis in the Sudan: clinical features, pathology and treatment

The clinical features, pathology, immune responses, diagnosis and treatment of post kala-azar dermal leishmaniasis (PKDL) in the Sudan are described and discussed. The disease is characterized by maculopapular or nodular lesions on the face, limbs or trunk. Lesions appear during or within months after the treatment of visceral leishmaniasis, but in 2 of 19 patients there was no previous history of kala-azar. PKDL may be confused with leprosy both clinically and pathologically. Similarities and differences between the 2 diseases are discussed. Unlike visceral leishmaniasis, the peripheral lymphoid cells of patients with PKDL respond to Leishmania antigen and some are leishmanin positive. The response to intravenous sodium stibogluconate (20 mg/kg for 30 d) was reasonably good but some patients required repeated or more prolonged treatment. Ketoconazole in a dose of 10 mg/kg daily for 4 weeks had no effect on PKDL.

Identification of Leishmania from mucosal leishmaniasis by recombinant DNA probes

Three cases of mucosal leishmaniasis are described. Parasites isolated from mucosal lesions were identified by Southern blot analysis of their genomic deoxyribonucleic acids (DNAs) using recombinant DNA probe pDK20. Parasites from 2 patients were identified as Leishmania donovani s.l. One of the patients had pure mucosal lesions, while in the second patient there was dissemination of the parasite to other organs. The spectrum of the disease caused by L. donovani is discussed. The parasite from the third patient was identified as L. major.

Malignant melanoma in goats: a clinico-pathological study

The clinicopathological features of 62 cases of malignant melanoma in goats in Sudan are described. The tumours occurred most frequently in grey or brown goats. The predilection site was the perineum. The tumour invaded locally and metastasized through lymphatics and blood vessels. Surgical excision of the tumour was followed or preceded by lymphadenectomy in some cases. The tumour was highly malignant and carried a poor prognosis. Possible aetiological factors are discussed.

Palliation of multiple bone metastases from prostatic carcinoma with strontium-89

The efficacy of strontium-89 in relieving pain caused by disseminated bone metastases was studied in 11 patients with prostatic carcinoma. The therapy consisted either of 3 i.v. injections of 100 MBq strontium-89 chloride in intervals of 4 weeks in 8 patients or 200 MBq i.v. administered on one occasion in 3 patients. The study suggests that 1-3 i.v. injections of 100 MBq strontium-89 may be a worthwhile and fairly atoxic treatment for palliation of bone pain from metastatic prostatic carcinoma.

Chronic obstructive mastitis in the camel. A clinicopathological study

Unilateral chronic mastitis in three she camels was due to obstruction of the teat canal by keratin. This lead to dilatation of the ducts, retention of milk and secondary bacterial infection. The teat canals and dilated ducts were lined by stratified squamous epithelium. There was excessive periductal fibrosis. Pasteurella hemolytica was isolated from one animal and Staphylococcus aureus from another. The fluid from the third animal was sterile. The condition was treated successfully by surgical amputation of the affected halves of the udder.

Immunohistological investigations in chronic cutaneous leishmaniasis in Saudi Arabia

The distribution and numbers of IgG-, IgA-, IgM-, and lysozyme-positive cells were investigated by the immunoperoxidase method in paraffin-sections of 13 cases of chronic cutaneous leishmaniasis of low parasite load from Saudi Arabia. The majority of the peroxidase-positive plasma cells contained IgG, whereas the numbers of IgA+ and IgM+ plasma cells were not so numerous. Small groups of squamous epithelial cells showed immunoreactivity for IgG and IgA. Similar positive staining was observed extracellularly in the oedematous upper dermis, in the endothelial cells, and in the perivascular space. The activated macrophages showed strong and diffuse peroxidase staining for lysozyme, whereas epithelioid cells and multinucleated giant cells were negative or had finely granular and considerably weaker staining. It is suggested that humoral immunity also participates in the elimination of the parasites and an immunologically induced necrosis might be responsible for the ulceration of the skin in cutaneous leishmaniasis. It is also assumed that the lysozyme immunoreactivity can be a marker of the activation state of the macrophages.

Vascular changes in human leishmaniasis: a light microscope and immunohistological study

The study of human cutaneous leishmaniasis from Saudi Arabia (37 cases), and of Sudanese mucosal (52 cases) and visceral (27 cases) leishmaniasis revealed the occurrence of vascular alterations. Vasculitis with or without fibrinoid necrosis and fibrin thrombi were found in both the arteries and veins within the area of inflammation in cutaneous and mucosal leishmaniasis; whereas subendothelial oedema, hyalinosis and intimaproliferation were seen in the small arteries of the various organs in visceral leishmaniasis. Immunoperoxidase staining of the cutaneous leishmaniasis lesions showed the presence of IgG and IgA within the endothelial cells, in the media, and in the perivascular space of the diseased vessels. The formation of immune complexes, locally in cutaneous and mucosal leishmaniasis and circulating in visceral leishmaniasis, is considered responsible for these vascular lesions.

Immunohistochemical demonstration of S-100 protein antigen-containing cells in chronic cutaneous leishmaniasis

The presence and distribution of S-100 protein antigen and lysozyme were investigated by the immunoperoxidase method in paraffin sections of 13 cases of chronic cutaneous leishmaniasis from Saudi Arabia. Varying numbers of S-100+lys- histiocytic reticulum cells were found in the dense inflammatory infiltrate in 11 out of 13 cases. These cells were considerably more numerous in the lesions dominated by cells of the mononuclear phagocytic system and granulomata than in the cases with plasma cellular or lymphocytic predominance. Activated lys+ macrophages, epithelioid cells, and multinucleated giant cells were always S-100-. Around the granulomata several S-100+lys- histiocytic reticulum cells could be found. These findings suggest that antigen-presenting cells are present in the inflammatory infiltrate of cutaneous leishmaniasis.