Pericytes and vascular smooth muscle cells in central nervous system arteriovenous malformations

Previously considered passive support cells, mural cells-pericytes and vascular smooth muscle cells-have started to garner more attention in disease research, as more subclassifications, based on morphology, gene expression, and function, have been discovered. Central nervous system (CNS) arteriovenous malformations (AVMs) represent a neurovascular disorder in which mural cells have been shown to be affected, both in animal models and in human patients. To study consequences to mural cells in the context of AVMs, various animal models have been developed to mimic and predict human AVM pathologies. A key takeaway from recently published work is that AVMs and mural cells are heterogeneous in their molecular, cellular, and functional characteristics. In this review, we summarize the observed perturbations to mural cells in human CNS AVM samples and CNS AVM animal models, and we discuss various potential mechanisms relating mural cell pathologies to AVMs.

Rbpj Deficiency Disrupts Vascular Remodeling via Abnormal Apelin and Cdc42 (Cell Division Cycle 42) Activity in Brain Arteriovenous Malformation

BACKGROUND

Brain arteriovenous malformations (bAVM) are characterized by enlarged blood vessels, which direct blood through arteriovenous shunts, bypassing the artery-capillary-vein network and disrupting blood flow. Clinically, bAVM treatments are invasive and not routinely applicable. There is critical need to understand mechanisms of bAVM pathologies and develop pharmacological therapies.

METHODS

We used an in vivo mouse model of Rbpj-mediated bAVM, which develops pathologies in the early postnatal period and an siRNA in vitro system to knockdown RBPJ in human brain microvascular endothelial cells (ECs). To understand molecular events regulated by endothelial Rbpj, we conducted RNA-Seq and chromatin immunoprecipitation-Seq analyses from isolated brain ECs.

RESULTS

Rbpj-deficient (mutant) brain ECs acquired abnormally rounded shape (with no change to cell area), altered basement membrane dynamics, and increased endothelial cell density along arteriovenous shunts, compared to controls, suggesting impaired remodeling of neonatal brain vasculature. Consistent with impaired endothelial cell dynamics, we found increased Cdc42 (cell division cycle 42) activity in isolated mutant ECs, suggesting that Rbpj regulates small GTPase (guanosine triphosphate hydrolase)-mediated cellular functions in brain ECs. siRNA-treated, RBPJ-deficient human brain ECs displayed increased Cdc42 activity, disrupted cell polarity and focal adhesion properties, and impaired migration in vitro. RNA-Seq analysis from isolated brain ECs identified differentially expressed genes in mutants, including Apelin, which encodes a ligand for G protein-coupled receptor signaling known to influence small GTPase activity. Chromatin immunoprecipitation-Seq analysis revealed chromatin loci occupied by Rbpj in brain ECs that corresponded to G-protein and Apelin signaling molecules. In vivo administration of a competitive peptide antagonist against the Apelin receptor (Aplnr/Apj) attenuated Cdc42 activity and restored endothelial cell morphology and arteriovenous connection diameter in Rbpj-mutant brain vessels.

CONCLUSIONS

Our data suggest that endothelial Rbpj promotes rearrangement of brain ECs during cerebrovascular remodeling, through Apelin/Apj-mediated small GTPase activity, and prevents bAVM. By inhibiting Apelin/Apj signaling in vivo, we demonstrated pharmacological prevention of Rbpj-mediated bAVM.

Endothelial Rbpj deletion normalizes Notch4-induced brain arteriovenous malformation in mice

Upregulation of Notch signaling is associated with brain arteriovenous malformation (bAVM), a disease that lacks pharmacological treatments. Tetracycline (tet)-regulatable endothelial expression of constitutively active Notch4 (Notch4*tetEC) from birth induced bAVMs in 100% of mice by P16. To test whether targeting downstream signaling, while sustaining the causal Notch4*tetEC expression, induces AVM normalization, we deleted Rbpj, a mediator of Notch signaling, in endothelium from P16, by combining tet-repressible Notch4*tetEC with tamoxifen-inducible Rbpj deletion. Established pathologies, including AV connection diameter, AV shunting, vessel tortuosity, intracerebral hemorrhage, tissue hypoxia, life expectancy, and arterial marker expression were improved, compared with Notch4*tetEC mice without Rbpj deletion. Similarly, Rbpj deletion from P21 induced advanced bAVM regression. After complete AVM normalization induced by repression of Notch4*tetEC, virtually no bAVM relapsed, despite Notch4*tetEC re-expression in adults. Thus, inhibition of endothelial Rbpj halted Notch4*tetEC bAVM progression, normalized bAVM abnormalities, and restored microcirculation, providing proof of concept for targeting a downstream mediator to treat AVM pathologies despite a sustained causal molecular lesion.

Pathological pericyte expansion and impaired endothelial cell-pericyte communication in endothelial Rbpj deficient brain arteriovenous malformation

Pericytes, like vascular smooth muscle cells, are perivascular cells closely associated with blood vessels throughout the body. Pericytes are necessary for vascular development and homeostasis, with particularly critical roles in the brain, where they are involved in regulating cerebral blood flow and establishing the blood-brain barrier. A role for pericytes during neurovascular disease pathogenesis is less clear—while some studies associate decreased pericyte coverage with select neurovascular diseases, others suggest increased pericyte infiltration in response to hypoxia or traumatic brain injury. Here, we used an endothelial loss-of-function Recombination signal binding protein for immunoglobulin kappa J region (Rbpj)/Notch mediated mouse model of brain arteriovenous malformation (AVM) to investigate effects on pericytes during neurovascular disease pathogenesis. We tested the hypothesis that pericyte expansion, via morphological changes, and Platelet-derived growth factor B/Platelet-derived growth factor receptor β (Pdgf-B/Pdgfrβ)-dependent endothelial cell-pericyte communication are affected, during the pathogenesis of Rbpj mediated brain AVM in mice. Our data show that pericyte coverage of vascular endothelium expanded pathologically, to maintain coverage of vascular abnormalities in brain and retina, following endothelial deletion of Rbpj. In Rbpj-mutant brain, pericyte expansion was likely attributed to cytoplasmic process extension and not to increased pericyte proliferation. Despite expanding overall area of vessel coverage, pericytes from Rbpj-mutant brains showed decreased expression of Pdgfrβ, Neural (N)-cadherin, and cluster of differentiation (CD)146, as compared to controls, which likely affected Pdgf-B/Pdgfrβ-dependent communication and appositional associations between endothelial cells and pericytes in Rbpj-mutant brain microvessels. By contrast, and perhaps by compensatory mechanism, endothelial cells showed increased expression of N-cadherin. Our data identify cellular and molecular effects on brain pericytes, following endothelial deletion of Rbpj, and suggest pericytes as potential therapeutic targets for Rbpj/Notch related brain AVM.

Endothelial Rbpj Is Required for Cerebellar Morphogenesis and Motor Control in the Early Postnatal Mouse Brain

Intercellular influences are necessary for coordinated development and function of vascular and neural components in the brain. In the early postnatal period after birth, the mammalian cerebellum undergoes extensive morphogenesis - developing its characteristic lobules, organizing its diverse cell types into defined cellular layers, and establishing neural circuits that support cerebellar function, such as coordinated movement. In parallel, the cerebellar vasculature undergoes extensive postnatal growth and maturation, keeping pace with the expanding neural compartment. Endothelial deletion of Rbpj leads to neurovascular abnormalities in mice, including arteriovenous (AV) shunts that supplant capillaries and instead direct high-pressure/high-flow arterial blood directly to veins. Gross and histopathological cerebellar abnormalities, associated with these Rbpj-mediated brain AV malformations (AVMs), led to our hypothesis that early postnatal morphogenesis and lamination of cerebellum was perturbed in mice harboring endothelial Rbpj deficiency from birth. Here, we show that endothelial Rbpj-mutant mice developed enlarged vascular malformations on the cerebellar surface, by 2-week post-Rbpj deletion. In addition, outgrowth of cerebellar lobules was impaired through decreased cell proliferation, but not increased apoptosis, in the external granule layer. Molecular layer thickness was reduced, and the Purkinje layer was affected, by decreased Purkinje cell number, primary dendrite length, and dendritic arbor density. Endothelial deletion of Rbpj also led to impaired motor behaviors, consistent with abnormal cerebellar morphogenesis and lamination. Thus, our data suggest that Rbpj is required, in early postnatal vascular endothelium, to ensure proper cerebellar outgrowth, morphogenesis, and function in mice.

Fluorescence Microscopy for ATP Internalization Mediated by Macropinocytosis in Human Tumor Cells and Tumor-xenografted Mice

Adenosine triphosphate (ATP), including extracellular ATP (eATP), has been shown to play significant roles in various aspects of tumorigenesis, such as drug resistance, epithelial-mesenchymal transition (EMT), and metastasis. Intratumoral eATP is 10³ to 10⁴ times higher in concentration than in normal tissues. While eATP functions as a messenger to activate purinergic signaling for EMT induction, it is also internalized by cancer cells through upregulated macropinocytosis, a specific type of endocytosis, to perform a wide variety of biological functions. These functions include providing energy to ATP-requiring biochemical reactions, donating phosphate groups during signal transduction, and facilitating or accelerating gene expression as a transcriptional cofactor. ATP is readily available, and its study in cancer and other fields will undoubtedly increase. However, eATP study remains at an early stage, and unresolved questions remain unanswered before the important and versatile activities played by eATP and internalized intracellular ATP can be fully unraveled. These authors' laboratories' contributions to these early eATP studies include microscopic imaging of non-hydrolysable fluorescent ATP, coupled with high- and low-molecular weight fluorescent dextrans, which serve as macropinocytosis and endocytosis tracers, as well as various endocytosis inhibitors, to monitor and characterize the eATP internalization process. This imaging modality was applied to tumor cell lines and to immunodeficient mice, xenografted with human cancer tumors, to study eATP internalization in vitro and in vivo. This paper describes these in vitro and in vivo protocols, with an emphasis on modifying and finetuning assay conditions so that the macropinocytosis-/endocytosis-mediated eATP internalization assays can be successfully performed in different systems.

Endothelial notch signaling is essential to prevent hepatic vascular malformations in mice

Liver vasculature is crucial for adequate hepatic functions. Global deletion of Notch signaling in mice results in liver vascular pathologies. However, whether Notch in endothelium is essential for hepatic vascular structure and function remains unknown. To uncover the function of endothelial Notch in the liver, we deleted Rbpj, a transcription factor mediating all canonical Notch signaling, or Notch1 from the endothelium of postnatal mice. We investigated the hepatic vascular defects in these mutants. The liver was severely affected within 2 weeks of endothelial deletion of Rbpj from birth. Two-week old mutant mice had enlarged vessels on the liver surface, abnormal vascular architecture, and dilated sinusoids. Vascular casting and fluorosphere passage experiments indicated the presence of porto-systemic shunts. These mutant mice presented with severely necrotic liver parenchyma and significantly larger hypoxic areas, likely resulting from vascular shunts. We also found elevated levels of VEGF receptor 3 together with reduced levels of ephrin-B2, suggesting a possible contribution of these factors to the generation of hepatic vascular abnormalities. Deletion of Rbpj from the adult endothelium also led to dilated sinusoids, vascular shunts, and necrosis, albeit milder than that observed in mice with deletion from birth. Similar to deletion of Rbpj, loss of endothelial Notch1 from birth led to similar hepatic vascular malformations within 2 weeks.

CONCLUSIONS

Endothelial Notch signaling is essential for the development and maintenance of proper hepatic vascular architecture and function. These findings may elucidate the molecular pathogenesis of hepatic vascular malformation and the safety of therapeutics inhibiting Notch. (Hepatology 2016;64:1302-1316).

Reinfection with varicella-zoster virus in immunocompromised patients

A small epidemic of varicella/atypical generalized zoster among 6 immunocompromised patients and one previously healthy person is described. The 6 immunocompromised patients suffered from lymphoproliferative diseases in terminal stages treated with chemotherapy and reported varicella in their childhood. They developed a generalized maculopapular rash with hemorrhagic bullae and necroses. The infection passed from one patient to another during a 3-month period in the department. They were placed in adjacent rooms and nursed by the same staff. The most specific diagnostic tool was the detection of varicella-zoster virus antigen from vesicles by ELISA technique. The epidemic was supposed to be caused by exogenous reinfection with varicella-zoster virus, and illustrated that generalized zoster may be even so infectious as varicella and that immunocompromised patients should be protected against reinfection.

Deletion of Rbpj from postnatal endothelium leads to abnormal arteriovenous shunting in mice

Arteriovenous malformations (AVMs) are tortuous vessels characterized by arteriovenous (AV) shunts, which displace capillaries and shunt blood directly from artery to vein. Notch signaling regulates embryonic AV specification by promoting arterial, as opposed to venous, endothelial cell (EC) fate. To understand the essential role of endothelial Notch signaling in postnatal AV organization, we used inducible Cre-loxP recombination to delete Rbpj, a mediator of canonical Notch signaling, from postnatal ECs in mice. Deletion of endothelial Rbpj from birth resulted in features of AVMs by P14, including abnormal AV shunting and tortuous vessels in the brain, intestine and heart. We further analyzed brain AVMs, as they pose particular health risks. Consistent with AVM pathology, we found cerebral hemorrhage, hypoxia and necrosis, and neurological deficits. AV shunts originated from capillaries (and possibly venules), with the earliest detectable morphological abnormalities in AV connections by P8. Prior to AV shunt formation, alterations in EC gene expression were detected, including decreased Efnb2 and increased Pai1, which encodes a downstream effector of TGFβ signaling. After AV shunts had formed, whole-mount immunostaining showed decreased Efnb2 and increased Ephb4 expression within AV shunts, suggesting that ECs were reprogrammed from arterial to venous identity. Deletion of Rbpj from adult ECs led to tortuosities in gastrointestinal, uterine and skin vascular beds, but had mild effects in the brain. Our results demonstrate a temporal requirement for Rbpj in postnatal ECs to maintain proper artery, capillary and vein organization and to prevent abnormal AV shunting and AVM pathogenesis.

Sonic hedgehog is required for vascular outgrowth in the hindbrain choroid plexus

Critical to the exchange and metabolic functions served by tissues like brain choroid plexi and lung is the coherent development of an epithelial sheet of large surface area in tight apposition to an extensive vascular bed. Here, we present functional experiments in the mouse demonstrating that Sonic hedgehog (Shh) produced by hindbrain choroid plexus epithelium induces the extensive vascular outgrowths and vascular surface area fundamental to choroid plexus functions, but does not induce the more specialized endothelial cell features of fenestrations and bore size. Our findings indicate that these Shh-dependent vascular elaborations occur even in the presence of Vegf and other established angiogenic factors, suggesting either that the levels of these factors are inadequate in the absence of Shh or that a different set of factors may be more essential to choroid plexus outgrowth. Transducing the Shh signal is a perivascular cell-the pericyte-rather than the more integral vascular endothelial cell itself. Moreover, our findings suggest that hindbrain choroid plexus endothelial cells, as compared to other vascular endothelial cells, are more dependent upon pericytes for instruction. Thus, in addition to Shh acting on the progenitor pool for choroid plexus epithelial cells, as previously shown, it also acts on choroid plexus pericytes, and together serves the important role of coordinating the development of two disparate yet functionally dependent structures-the choroid plexus vasculature and its ensheathing epithelium.

Trend towards Decreased Survival in Patients Infected with HIV Resistant to Zidovudine

The survival of 35 patients with AIDS or advanced HIV infection on treatment with zidovudine was related to the viral sensitivity to the drug and to the CD4+ cell count. 14 patients died, the survivors were followed up for an average of 804 days. In a univariate Cox model, survival was strongly related to log IC90 (p = 0.0003) and to the CD4+ count (p = 0.0002). In a bivariate model, log IC90 and the CD4+ count contributed to the prediction of survival (p = 0.12 and 0.06, respectively). Large studies of combination or alternation therapy with several anti-HIV drugs should be given high priority.

Hh pathway expression in human gut tissues and in inflammatory gut diseases

Sonic hedgehog (Shh) directs early gut patterning via epithelial-mesenchymal signaling and remains expressed in endoderm-derived tissues into the adult period. In human adult gut epithelium SHH/SHH expression is strongest in basal layers, which suggests that SHH may function in the maintenance of gut epithelial stem or progenitor cells. Recent publications suggest a role for aberrant SHH/SHH expression in gut epithelial neoplasias. We hypothesized that the regenerating gut epithelium in inflammatory gut disorders would show an upregulation of SHH/SHH signaling and this abnormal signal may explain the increased incidence of neoplasia in these diseases. Archived healthy gut and inflammatory gut diseased tissues were analyzed by RNA in situ hybridization and immunohistochemistry to describe location and levels of SHH signaling. We show that SHH/SHH and its receptor PTCH1/PTCH1 expression is restricted to the glandular epithelium of the gut, in an antiluminal pattern (strongest in basal layers and weak to absent in luminal epithelium). Inflammatory diseases of the gut show dramatic increases in epithelial SHH signaling. Expression increases in inflamed glandular epithelium (including metaplastic glandular epithelium), losing its radial (crypt-villous) polarity, and expression appears upregulated and present in all epithelial cells. We also describe strong SHH/SHH and PTCH1/PTCH1 expression in intraepithelial and mucosal inflammatory cells. We suggest that SHH signaling in inflammatory diseases of the gut acts to ensure stem cell restitution of damaged mucosal epithelium. However, such signaling may also present a risk for neoplastic transformation.

SOX9 specifies the pyloric sphincter epithelium through mesenchymal-epithelial signals

Gastrointestinal (GI) development is highly conserved across vertebrates. Although several transcription factors and morphogenic proteins are involved in the molecular controls of GI development, the interplay between these factors is not fully understood. We report herein the expression pattern of Sox9 during GI development, and provide evidence that it functions, in part, to define the pyloric sphincter epithelium. SOX9 is expressed in the endoderm of the GI tract (with the exclusion of the gizzard) and its derivate organs, the lung and pancreas. Moreover, SOX9 is also expressed at the mesoderm of the pyloric sphincter, a structure that demarcates the gizzard from the duodenum. Using retroviral misexpression technique, we show that Sox9 expression in the pyloric sphincter is under the control of the BMP signaling pathway, known to play a key role in the development of this structure. By misexpressing SOX9 in the mesoderm of the gizzard, we show that SOX9 is able to transdifferentiate the adjacent gizzard epithelium into pyloric sphincter-like epithelium through the control of mesodermal-epithelial signals mediated in part by Gremlin (a modulator of the BMP pathway). Our results suggest that SOX9 is necessary and sufficient to specify the pyloric sphincter epithelial properties.

Hedgehog is an early and late mediator of pancreatic cancer tumorigenesis

Hedgehog signalling--an essential pathway during embryonic pancreatic development, the misregulation of which has been implicated in several forms of cancer--may also be an important mediator in human pancreatic carcinoma. Here we report that sonic hedgehog, a secreted hedgehog ligand, is abnormally expressed in pancreatic adenocarcinoma and its precursor lesions: pancreatic intraepithelial neoplasia (PanIN). Pancreata of Pdx-Shh mice (in which Shh is misexpressed in the pancreatic endoderm) develop abnormal tubular structures, a phenocopy of human PanIN-1 and -2. Moreover, these PanIN-like lesions also contain mutations in K-ras and overexpress HER-2/neu, which are genetic mutations found early in the progression of human pancreatic cancer. Furthermore, hedgehog signalling remains active in cell lines established from primary and metastatic pancreatic adenocarcinomas. Notably, inhibition of hedgehog signalling by cyclopamine induced apoptosis and blocked proliferation in a subset of the pancreatic cancer cell lines both in vitro and in vivo. These data suggest that this pathway may have an early and critical role in the genesis of this cancer, and that maintenance of hedgehog signalling is important for aberrant proliferation and tumorigenesis.

[Survival of patients with zidovudine resistant HIV]

The survival of 35 patients with AIDS or advanced HIV infection on zidovudine treatment was related to the viral sensitivity to the drug and to the CD4+ cell count. Fourteen patients died, the survivors were followed up for an average of 804 days. In a univariate Cox model, survival was strongly related to log IC90 (p = 0.0003) and to the CD4+ count (p = 0.0002). In a bivariate model, log IC90 and the CD4+ count contributed to the prediction of survival (p = 0.12 and 0.06, respectively). Large studies of combination or alternation therapy with several anti-HIV-drugs should be given high priority.

[Pneumococcal bacteremia in Hvidovre Hospital 1986-1990]

The study describes 156 consecutive cases of pneumococcal bacteraemia among patients admitted to Hvidovre Hospital during the five-year period 1986-1990. Pneumococcal bacteraemia was most common in the age groups 0-4 and 50-99 years. The most common focus of infection was the lungs (84%). 81% had preexisting diseases and the most common were: Immunosuppression due to drugs, alcoholism, cardiovascular disease, chronic obstructive lung disease, diabetes and myelomatosis. Patients over 65 years of age had a higher case fatality (35%) than younger (12%). The overall case fatality rate was 24%. Twenty-three percent of cases were hospital-acquired, and associated with a case fatality of 37%. Pneumococcal bacteraemia was most common during the winter season and unrelated to influenza. Eighty-four percent of the examined isolates represented capsular types included in the 23-valent pneumococcal vaccine. Three percent of the tested strains were relatively resistant to penicillin (MIC > 0.1 microgram/ml). Despite antibiotic treatment, the mortality from pneumococcal bacteraemia, particularly in elderly, remains high. With this in mind, one may consider offering pneumococcal vaccination to persons over 65 years of age with chronic predisposing diseases.

Synthesis and anti-HIV activity of 5-alkoxymethyl-3'-azido-2',3- dideoxyuridines

Methyl 3-azido-5-O-tert-butyldiphenylsilyl-2,3-dideoxy-D-erythro-furanosi de (3) was coupled with silylated 5-hydroxymethyluracil (1a) and its C1-C6 alkyl ethers 1b-g to give the corresponding protected nucleosides 4a-g which were deprotected with Bu4NF to afford 3-azido nucleosides 5a-g and 6a-g. The alpha-anomers 6f,g show moderate activity against HIV. No significant activity against HSV-1 was found for the compounds 5 and 6.

Hepatitis C virus antibodies in homosexual men and intravenous drug users in Denmark

In order to evaluate the role of sexual transmission and parenteral transmission of hepatitis C virus (HCV) in homosexual men and intravenous drug users (IVDU) serum samples from 147 homosexual men and 126 IVDU were tested for anti-HCV. Anti-HCV was found in two (1.4%) of the homosexual men and in 123 (98%) of IVDU. The presence of anti-HCV could not be correlated to the presence of HBV markers or HIV-antibodies. HCV is widespread among Danish IVDU. Risk of sexual transmission seems low even though sexual contact is a much more prevalent risk factor than needle sharing.

Development of resistance to zidovudine in HIV strains isolated from CD4+ lymphocytes and plasma during therapy

An assay based on production of HIV antigen in cultures of CD4+ lymphocytes infected 'in vitro' with cell-free virus was established. Using this assay it was possible to isolate, propagate and reliably determine the zidovudine susceptibility of HIV isolates from all patients despite differences in cellular tropism and syncytium inducing capacity. Using this assay, differences in zidovudine susceptibility of 52 serial isolates obtained from 16 patients before and after initiation of therapy were examined. HIV with a 10- to 100-fold reduced susceptibility to zidovudine were isolated from 13 patients as early as 4 months after initiation of therapy. Number of months of zidovudine treatment was strongly associated with development of viral resistance, and high CD4 cell counts tended to be associated with lower rates of development of resistance. That patients can harbor mixtures of virus strains with different susceptibility to zidovudine was confirmed by the differences in susceptibility between isolates obtained simultaneously from CD4+ lymphocyte and plasma, and by the differences in susceptibility between virus strains isolated from clones of CD4+ lymphocytes.

HIV-2 infection in Denmark

A collection of 3019 selected serum samples (ss), comprising 329 ss from intravenous drug abusers, 558 ss from homosexual men, 682 samples from persons attending a STD clinic, 100 ss from individuals of African origin, 300 ss from sexual contacts to Africans, 650 ss from Danish blood donors who resided in Africa greater than 2 years prior to donating the ss, and 400 ss with equivocal antibody reactions in an HIV-1 Western blot was tested for antibodies against HIV-2 by in-house HIV-2 ELISA and Western blot. Four ss were positive for antibodies against HIV-2. Three of the ss originated from West African men, the fourth belonged to the spouse of one of these men. Three of the samples presented with an uncharacteristic reaction in a HIV-1 Western blot. The study indicates that HIV-2 infection is not yet widespread in Denmark and that it remains closely related to West Africa.

Neutralizing antibodies against two HIV-1 strains in consecutively collected serum samples: cross neutralization and association to HIV-1 related disease

97 sera collected during a 10-year period from 10 HIV-1 infected individuals were tested for neutralizing capacity against a virus isolate FICPH-22 obtained from a Danish AIDS patient, and the laboratory strain HTLV-IIIB. Three patterns of serum neutralizing activity were demonstrated: (a) patients developing high neutralizing activity against both HIV strains; (b) patients developing high neutralizing activity against the Danish virus isolate; and (c) patients developing only low titers of neutralizing antibodies (NA) against both HIV strains. The HTLV-IIIB strain was less sensitive to serum neutralization than the FICPH-22 isolate and the appearance of NA against HTLV-IIIB was typically lacking several years behind that against FICPH-22 indicating a broadening of the NA response over time. No difference in clinical outcome was observed comparing patients reaching high titers of NA and patients with low titers. Development of AIDS among patients reaching high titers of NA was preceded by a decline in NA titers, indicating an association of high titers of NA with the healthy carrier state and of declining or low titers of NA with disease progression. The majority of the neutralizing activity was mediated by IgG, but some neutralizing activity was demonstrated in the IgG depleted serum, indicating the presence of additional neutralizing substances in serum.

Synthesis of 5-alkoxymethyl derivatives of 3'-amino-2',3'-dideoxyuridine and evaluation of their activity against HIV and cancer

5-Alkoxymethyluracils 2a-c have been prepared by acid-catalyzed etherification of 5-hydroxymethyluracil (1). Compounds 1, 2a-c, 5-methoxymethyl- and 5-benzyloxymethyl-uracil were silylated and coupled with 1,5-di-O-acetyl-3-phthalimido-2,3-dideoxy-beta- D-erythro-pentofuranose (3), in the presence of trimethylsilyl triflate as a catalyst, to give the corresponding 3'-phthalimido-2',3'-dideoxynucleosides 5a-f and 6 which on treatment with 33% methylamine-ethanol afforded the corresponding 3'-amino-2',3'-dideoxynucleosides 7a-f and 8 in high yields. Compound 7d showed colony inhibition when tested against human epidermoid cervical cancer cells. Nucleosides 5a-e, 7a-f and 8 did not show any significant activity against HIV-1.

Free-radical synthesis of 3-(2-cyanoethyl)- and 3-(2-methoxycarbonylethyl)-2,3-dideoxy-alpha-D-erythro-pentofu ranoside and their application in the synthesis of potential antiviral nucleosides

Free-radical reaction of different carbohydrate educts 2, 5, and 7 with acrylonitrile in the presence of tributyltin hydride and a radical initiator (AIBN) gave the methyl 3-(2-cyanoethyl)-2,3-dideoxypentofuranosides 3a and 6. Similar reaction of 2 with methyl acrylate gave 3-(2-methoxycarbonylethyl)-2,3-dideoxypentofuranose 3b. Nucleoside coupling of 3a with silylated uracil gave an anomeric mixture of beta- and alpha-nucleoside 8 and 9 which were deprotected to give 10 and 11, respectively. Similar reaction of 3b with silylated N4-isobutyrylcytosine gave 12 and 13 which were deprotected to give the final nucleosides 16 and 17, respectively. None of the compounds 10a, 11, 14-17 showed significant activity against HIV.

Isolation of HIV from cultures of purified CD4+ lymphocytes

Isolation of HIV from cultures of CD4+ lymphocytes purified from peripheral blood by indirect panning was optimized and evaluated. Infectious HIV was isolated by single isolation attempts in 98% of 102 HIV-antibody-positive patients (55 had AIDS or ARC and 47 were clinically healthy). The average culture time required for positive cultures was largely independent of the CD4 count of the patients and 87% of the positive isolation cultures from both groups of patients became positive within 14 days of culture. An evaluation of the possible influence of media additives on propagation of HIV showed that: amphotericin-B had a suppressive effect on HIV replication at concentrations recommended for anti-fungal activity; recombinant and human interleukin-2 were equally suitable for both isolation cultures and for propagation of HIV, and polybrene, at a concentration of 2 micrograms/ml in the culture medium had a beneficial effect.

New synthesis of 2',3'-didehydro-2',3'-dideoxynucleosides

The 3'-iodonucleoside 4 and the 3'-O-methylsulfonylthymidine 9 have been synthesized by condensation of silylated uracils 2 with methyl 5-O-tert-butyldiphensilyl-2,3-dideoxy-3-iodo-D-threo-pentofuran oside (3) and methyl 5-O-tert-butyldiphenylsilyl-2-deoxy-3-methylsulfonyl-D-erythro- pentofuranoside (8), respectively. The nucleoside 4 and 9 produced the corresponding 2',3'-didehydro-2',3'-dideoxynucleosides 5 in an elimination reaction on treatment with sodium methoxide. The compounds 5b showed no antiviral activity against HIV-1.

Synthesis and evaluation of antiviral activity of L-acosamine and L-ristosamine nucleosides of furanose configuration

Mercuric-catalyzed hydrolysis of acetylated L-rhamnal 1 gives an alpha,beta-unsaturated aldehyde 2. 1,4-Addition of DBU-phthalimide salt with concomitant acetyl shift resulted in L-ribo and L-arabino isomers of 5-O-acetyl-2,3,6-trideoxy-3-phthalimido-hexofuranose 3 and 4. After acetylation at the anomeric center, coupling with silylated thymine resulted in three new nucleosides, with L-acosamine and L-ristosamine of furanose configuration as the carbohydrate moiety. The target compounds have been evaluated for their antiviral activity against HIV and HSV-1.

HIV antigen-induced release of histamine from basophils from HIV infected patients. Mechanism and relation to disease progression and immunodeficiency

Basophil leukocytes from 39 HIV-infected patients with various degrees of immunodeficiency and disease progression were stimulated with an HIV antigen preparation. Cells from 19 of 22 patients with AIDS and all of six patients with milder degrees of HIV-related disease showed significant histamine release. In contrast, cells from 11 asymptomatic HIV-infected patients and 11 healthy control persons released no histamine. The histamine release induced by HIV antigen was found to be inversely correlated to the number of CD4 positive T lymphocytes. These results indicate that the histamine release was related to both the clinical stage of disease and the degree of immunodeficiency. Passive sensitization experiments showed that IgE, but not IgG, was responsible for the induction of histamine release, indicating the reaction to be type 1 allergic. The histamine release caused by HIV might be involved in the development of disease because of the immunomodulating properties of this mediator.

Detection of human immunodeficiency virus DNA in cultured human glial cells by means of the polymerase chain reaction

This report describes the use of the polymerase chain reaction (PCR) for the detection of viral genomic sequences in latently infected cells. Infection with human immunodeficiency virus in cultures of human glial cells was demonstrated, using nucleic acid amplification followed by dot blot hybridization. It was not possible to detect any viral antigen production in the cultures, and attempts to recover virus by highly sensitive coculture techniques were unsuccessful, indicating that the infection was latent. The PCR technique provides a simple approach to the study of viral infection in cases where viral replication is absent, or where genomic copies are present at such low numbers that they are otherwise undetectable.

Synthesis of 3'-amino-2',3'-dideoxy-hexofuranose nucleosides with potential anti-viral activity

Michael type addition of DBU (1,8-diazabicyclo[5,4,0]undec-7-ene) phthalimide salt to 4,6-di-O-acetyl-2,3-dideoxy-aldehydo-D-erythro-trans-hex-2-enos e 2 and concomitant acetyl shift give an anomeric mixture of arabino and ribo isomers of 5,6-di-O-acetyl-2,3-dideoxy-3-phthalimido-D-hexofuranose 3 which after acetylation at the anomeric hydroxy group is separated to give 4 and 5. Subsequent reaction with 5'-substituted silylated uracil in the presence of TMS-triflate results in three different 5',6'-di-O-acetyl-2',3'-dideoxy-3'-phthalimido-D-hexofuranose nucleosides 7, 9, and 10 which were deprotected to give the corresponding 3'-amino nucleosides 8, 11, and 12. The compounds 7-12 were investigated for their activity against HSV-1 and HIV-1.

Synthesis of N-substituted 3'-amino-3'-deoxythymidines and their biological evaluation against HIV

Treatment of 3'-amino-3'-deoxythymidine (1) with carboxylic acid anhydrides afforded the corresponding acylamino derivatives 2a-f. Reaction of 1 with a variety of isothiocyanates led to the corresponding thioureido derivatives 3a-i. Also, conversion of 1 into 3'-carbylamino-3'-deoxythymidine (7) is reported. The compounds 2, 3, and 8 were evaluated for their anti-HIV activity in MT-4 cells, but did not show sufficient efficacy.

Synthesis of 3'-(4-nitroimidazol-1-yl)-2',3'-dideoxynucleosides of pyrimidine analogues and their biological evaluation against HIV

Reaction of 1,5-di-O-acetyl-2,3-dideoxy-3-phthalimido-beta-D-erythro-pento-fur anose (1) with silylated pyrimidinediones 2a-c using the Lewis acid trimethylsilyl triflate as catalyst afforded nucleosides 3a-c and 4a,c which were deprotected with 33% methylamine/ethanol to give the corresponding 3-aminonucleosides 5a-c and 6. These were reacted with 1,4-dinitroimidazoles 7a,b to give the 3-imidazolyldideoxynucleosides 8a,b and 9a-f. At sub-toxic concentrations these compounds were ineffective against HIV-1.

Derivatives of amphotericin inhibit infection with human immunodeficiency virus in vitro by different modes of action

Three water-soluble derivatives of amphotericin B were tested for inhibition of HIV infection in vitro. The compounds amphotericin B methyl ester (AME) and N-(N'-(2-(4'-methylmorpholinio)ethyl)N"-cyclohexyl guanyl) amphotericin B methyl ester (MCG) inhibited HIV infection by 50% at 1 microgram/ml; N-(N'-(3-dimethylaminopropyl)N"-ethyl guanyl) amphotericin B (DAPEG) did so at 5-11 micrograms/ml. While the virus-inhibitory effect of AME was due to an interaction with target lymphocytes, the effect of MCG was due to a direct anti-viral action. AME increased the potential of infected cells to fuse with uninfected cells, but MCG had no significant effect on cell fusion. All compounds had a lower cellular toxicity than amphotericin B and were not toxic at concentrations below 20 micrograms/ml.

Inhibition of human immunodeficiency virus (HIV) infection in vitro by anticarbohydrate monoclonal antibodies: peripheral glycosylation of HIV envelope glycoprotein gp120 may be a target for virus neutralization

Carbohydrate structures are often involved in the initial adhesion of pathogens to target cells. In the present study, a panel of anticarbohydrate monoclonal antibodies (MAbs) was tested for their ability to inhibit in vitro human immunodeficiency virus infectivity. MAbs against three different N- and O-linked carbohydrate epitopes (LeY, A1, and sialyl-Tn) were able to block infection by cell-free virus as well as inhibit syncytium formation. Inhibition of virus infectivity was independent of virus strain (HTLVIIIB or patient isolate SSI-002), the cell line used for virus propagation (H9 or MT4), and the cell type used as the infection target (MT4, PMC, or selected T4 lymphocytes). Inhibition was observed when viruses were preincubated with MAbs but not when cells were preincubated with MAbs before inoculation, and the MAbs were shown to precipitate 125I-labeled gp120. The MAbs therefore define carbohydrate structures expressed by the viral envelope glycoprotein gp120, indicating that glycans of the viral envelope are possible targets for immunotherapy or vaccine development or both.

Oral candidiasis and hairy leukoplakia correlate with HIV infection in Tanzania

We report a detailed study on oral lesions and their association with the WHO revised provisional case definition of AIDS as well as serologic signs of HIV infection among 186 patients in Dar Es Salaam, Tanzania. The patient material consisted of 39 hospitalized suspected AIDS patients, 44 medical nonsuspected patients, 53 dental outpatients, and 50 patients with sexually transmitted diseases. The male:female ratio was 2.1:1 on average. Oral examination was done without knowledge of the HIV status of the patients. Among 39 suspected AIDS patients 97% had WHO AIDS criteria and 90% were seropositive for HIV. Among the 147 patients not suspected of having AIDS 18 (12%) had AIDS criteria and 15% had serologic evidence of HIV infection. The presence of WHO AIDS criteria correlated significantly with the presence of HIV antibodies, but not with HIV antigen. Oral lesions were found in 54% of those with AIDS criteria and 52% of HIV-infected patients, as compared to 3% and 6% of the patients without AIDS criteria and HIV infection, respectively (p less than 0.01). Among patients with AIDS atrophic candidiasis occurred in 21%, pseudomembranous candidiasis in 23%, hairy leukoplakia in 36%, herpetic stomatitis in 2%, Kaposi's sarcoma in 4%, and nonspecific ulcer in 4%. The presence of oral lesions had a high predictive value for presence of AIDS criteria as well as for presence of HIV infection in this hospital setting. All patients should have a thorough oral examination and the presence of the aforementioned oral lesions should lead to testing for HIV infection.

Immunofluorescence assay for detection of antibodies to human immunodeficiency virus type 2

A total of 215 serum samples were tested for antibodies against human immunodeficiency virus type 2 (HIV-2) with an immunofluorescence assay (IFA). Some samples originated from Denmark and some originated from Guinea-Bissau. The IFA results were compared with enzyme-linked immunosorbent assay (ELISA) and Western (immuno-) blot (WB) results. Twenty-nine serum samples were found to be true positive for HIV-2 antibodies as judged from WB and radioimmunoprecipitation results; all of these were also found to be positive in the HIV-2 IFA. Of 80 serum samples originating from HIV-1-infected persons, 60% showed reactivity in the HIV-2 ELISA, and 51% cross-reacted with at least one band in the HIV-2 WB. None of the sera cross-reacted in the HIV-2 IFA. A total of five serum samples (three African and two Danish) gave unspecific results in the HIV-2 IFA. It is concluded that the HIV-2 IFA is more specific and at least as sensitive as a first-generation ELISA and that IFA is superior to WB in discriminating between HIV-1 and HIV-2 infections.

Isolation of HIV using T-lymphocyte 'panning': methodological aspects

A technique for isolation of HIV using selective cultures of T4 cells obtained from peripheral blood by immunochemical separation was developed and optimized. Using this method infectious virus could be isolated in single isolation attempts from 89% of 35 HIV-infected patients in different stages of immunodeficiency. This isolation frequency was virtually independent of the stage of the disease, in contrast to the results obtained by the conventional isolation technique based on peripheral mononuclear cells (PMC). It is concluded that isolation of HIV from selected T4 cells is superior to other methods when isolation is attempted from healthy HIV-infected individuals.

Explants of human oral epithelium exposed to viruses and cancer chemotherapeutics

Cultures of proliferating epithelial cells were established from explants of normal human oral epithelium from healthy young volunteers. The epithelial cells were found permissive for herpes simplex virus type 1 and type 2, coxsackie virus A-4 and A-16, adenovirus type 5, measles vaccine, rubella and influenza type A virus-. Medium from DEAE-pretreated epithelial cultures infected with two subtypes of human immunodeficiency virus-1 showed an increasing content of virusprotein with time by antigen ELISA testing. In contrast there was no evidence of infection with coxsackie virus type B-2, cytomegalovirus, Epstein-Barr virus and varicella zoster virus. Treatment of the epithelial cells with a non-cytotoxic dose of cancer chemotherapeutic prior to or after infection with coxsackie virus A-4 or herpes simplex virus type 1 influenced the virus production dependent on both compound, mode of application, and virus. Adriamycin (doxorubicin) in low dose was found to stimulate the production of the two viruses.

Antigen-antibody reaction in solution in capture competition immunoassay for human immunodeficiency virus antibodies

In the capture competition immunoassay, undiluted serum was reacted in solution with purified human immunodeficiency virus (HIV) antigen in wells of microtest plates coated with anti-HIV immunoglobulin G antibodies (HIV capture antibodies). HIV antibodies present in the serum being tested combined with the HIV antigen and thus blocked (completely or partially) the fixation of the antigen to the capture layer. Unblocked antigenic activity was measured in subsequent steps by the use of biotinylated anti-HIV immunoglobulin G and peroxidase-conjugated avidin. The assay was evaluated in comparison with indirect enzyme-linked immunosorbent assay and Western (immuno-) blot (WB). A total of 180 serum samples which reacted repeatedly as positive in indirect enzyme-linked immunosorbent assay but negative in WB were found to be negative by the capture competition assay. Of 54 serum samples showing dubious reactions (single p24 bands in WB), 53 were clearly separated into positive or negative reactions, whereas 1 serum sample gave a borderline reaction. It was concluded that a characteristic feature of this kind of inhibition assay is a very low frequency of equivocal results.

[A mini epidemic of varicella zoster virus reinfection at a department of hematology]

Whereas primary infection with varicella zoster virus (VZV) (chickenpox) and reactivation of VZV (shingles) are common and recognized, clinical reinfection with VZV is rare. A little epidemic of presumed reinfection with VZV in six immune-compromised adults is presented here. The epidemic lasted for three months, during which a healthy young woman also developed a primary VZV infection in the form of chickenpox. In the immune-compromised patients, the clinical picture was dominated by disseminated, prolonged and frequently haemorrhagic and necrotic eruptions which may cause diagnostic difficulties. Skin biopsy proved helpful in the diagnosis while demonstration of the VZV antigen in the skin elements was specific and sensitive. All of the patients, with one exception, were treated with acyclovir and dissemination of the infection to the inner organs did not occur. One patient may have died on account of the VZV infection. In conclusion, immune-incompetent patients must be warned against infection from chickenpox or disseminated herpes zoster. In cases of proved exposure, prophylactic treatment with acyclovir should be considered and, in cases of clinical disease, immediate treatment with 10 mg acyclovir per kg body weight should be administered intravenously thrice daily.

HIV antigen stimulates basophil leukocytes from AIDS patients to release histamine due to type I allergy

HIV antigen-induced histamine release was examined in leukocyte suspensions from 12 patients with AIDS and 10 healthy controls. Nine of the twelve patients released histamine, while no release was obtained in cells from the control group. The mechanism was examined by removal of immunoglobulins (Ig) from the patient cells before stimulation with HIV antigen, which resulted in an abolition of the histamine release. Transfer of the Ig to cells from normal individuals rendered these cells able to respond to HIV. The removal and fixation of Ig were followed by disappearance and reappearance of the response to anti-IgE. These findings indicate that the histamine release by HIV is caused by a type I (IgE-mediated) reaction.

Sexually transmitted diseases, antibodies to human immunodeficiency virus, and subsequent development of acquired immunodeficiency syndrome. Visitors of homosexual sauna clubs in Copenhagen: 1982-1983

Sera from 260 men from Denmark and elsewhere attending two Copenhagen sauna clubs for homosexual men during nine months of 1982-1983 were investigated for markers for syphilis, hepatitis A and B, and human immunodeficiency virus (HIV). Five per cent (12 men) had active syphilis, and another 35% (92) had a history of and/or serologic markers for syphilis. Ninety-four men (36%) were positive for antibodies to hepatitis A virus, ten (4%) were positive for hepatitis B surface antigen (HBsAg), and 153 (59%) were positive for antibodies to HBsAg. Antibodies to HIV were found in 45 (20%) of the 220 men investigated for this marker. Markers for hepatitis A and B and for syphilis were more frequent in the HIV antibody-positive individuals, but the association was significant only for markers for hepatitis B (relative risk = 2.0). Thus STD markers had little predictive value for seropositivity for antibodies to HIV. Among 37 men investigated more than once, a seroconversion rate of 3% per month for antibodies to HIV was found, but this estimate must be taken with reservation. The rate of seropositivity for antibodies to HIV among men from Denmark was 23%, and three (8%) of the 40 HIV-positive Danish men developed the acquired immunodeficiency syndrome (AIDS) during the four years following the initial investigation. This study shows that by 1982-1983 HIV had spread considerably in the Danish high-risk group, although there were only seven reported cases of AIDS in the country at that time.

Temporal relation of antigenaemia and loss of antibodies to core antigens to development of clinical disease in HIV infection

A total of 276 sequential serum samples from 34 men with antibodies to the human immunodeficiency virus (HIV) followed up for two to seven years were analysed for HIV antigen and antibodies to the viral core and envelope proteins. Results were correlated with clinical outcome and CD4 T lymphocyte count. Both antigenaemia and the disappearance of antibodies to the core protein were associated with development of the acquired immune deficiency syndrome (AIDS) or AIDS related complex and depletion of CD4 cells. Thus AIDS or AIDS related complex developed in eight out of 16 patients with antigenaemia compared with one out of 18 patients without antigenaemia. Low counts of CD4 cells (less than 0.5 X 10(9)/l) were found in 14 of the 16 patients with antigenaemia and five of the 18 without antigenaemia. Nine patients seroconverted to HIV during the study; two of these developed antigenaemia 14 and 16 months after the estimated time of seroconversion. These results show that the late stages of HIV infection are characterised by increased production of antigen and a decrease in antibodies directed against the core protein. Antigenaemia indicates a poor prognosis; and as the antigen test is simple to do and interpret, it may therefore be useful for selecting patients for antiviral treatment.

A biotin-avidin-amplified inhibition enzyme immunoassay for detection of CMV antibodies in human serum

In this inhibition immunoassay undiluted serum reacts in solution with crude cellular CMV antigen in wells of microtestplates coated with hyperimmune CMV-reactive monkey IgG. CMV antibodies in the serum under test block (completely or partial) the fixation of antigen to the capture layer. Unblocked antigenic activity is in subsequent steps measured by the use of biotinylated CMV-reactive monkey IgG and peroxidase-conjugated avidin. The assay was evaluated in comparison with the CF test and was found superior both in terms of qualitative and quantitative detection of CMV antibodies. The results were uninfluenced by the presence in the sera of rheumatoid factor or autoantibodies (antinuclear antibodies). A characteristic feature of this inhibition immunoassay was the absence of equivocal results as demonstrated by analysis of 500 donor sera which were classified in two distinct separate groups: reactive and nonreactive. The assay is simple and reproducible and provides for a good reagent economy. Crude antigen can be used without sacrifice of specificity. Antigen from one Roux bottle proved sufficient for 25,000 duplicate tests.

An enzyme labelled nuclear antigen immunoassay for detection of cytomegalovirus IgM antibodies in human serum: specific and non-specific reactions

A mu-capture enzyme linked immunosorbent assay was developed for detection of IgM antibody to cytomegalovirus (CMV). Virus-specific IgM was detected using horseradish peroxidase labelled nuclear CMV antigen (CMV-ELA). False-positive reactions caused by Paul-Bunnell-Davidsohn (PBD) positive sera and antinuclear antibody (ANA) positive sera were identified in a combination assay employing enzyme labelled nuclear control antigen (CO-ELA) in parallel to the CMV-ELA. Four of five PBD positive and 30 of 31 ANA positive sera reactive with the CMV-ELA were identified as false positive reactions in the combined ELA-assay. The reactivity in PBD-positive sera could not be explained by antigenic cross reactivity between CMV and Epstein-Barr virus, and the results further suggested that different cell specified components of the CMV-ELA were responsible for the reactivity of PBD-positive as compared to ANA-positive sera. One of 314 healthy blood donors, 12 of 12 patients with primary CMV infection, and 11 of 15 patients with secondary CMV infection had detectable CMV IgM antibodies. Comparison of different CMV-ELAs revealed that pronounced differences in specificity as well as sensitivity may exist.

Comparison of four serological tests for the detection of specific immunoglobulin M in cord sera of infants congenitally infected with cytomegalovirus

Four serological tests (3 immunoassays using enzyme-labelled antigen and 1 radioimmunoassay) were compared as regards the detection of cytomegalovirus (CMV) immunoglobulin M in cord sera. 68 cord sera from infants congenitally infected by CMV were included in the study. The infections were primarily diagnosed by virus isolation close to birth. Four laboratories in 3 countries were involved, each laboratory using its own or a commercial test. Of the sera tested in the different laboratories 50-80% were found to be reactive. Both qualitatively and quantitatively there was a good correlation between the 3 enzyme-immunoassays. The RIA results differed to some extent from the enzyme tests as regards the quantification of IgM. The advantage of prospective IgM screening in undiluted cord sera followed by confirmatory virus isolation test in the neonatal period in IgM-positive cases is discussed.

A prospective study on infection with cytomegalovirus in renal allograft recipients immunosuppressed with cyclosporine A and low dose prednisone

To investigate the course of infection with cytomegalovirus (CMV) in renal allograft recipients treated with cyclosporine A, 10 patients were followed for 1 year after transplantation. Virus cultures from blood, urine and throat washings were performed employing a quantitative technique. Complement-fixing and IgM antibodies to CMV were measured at scheduled intervals. The incidence 90% and course of CMV infections were found not to differ from those reported in patients receiving conventional immunosuppressive therapy. The quantitative virus cultures showed a consistent pattern with viremia most prominent at the beginning of an infection, and the highest concentration found in the one patient who developed symptoms of viral disease. It is suggested that information about the concentration of virus in a specimen will improve the diagnostic value of virus cultures in this group of patients.

Stages in LAV/HTLV-III lymphadenitis. II. Correlation with clinical and immunological findings

The aim of the present study was to investigate the relation between the histopathological findings in LAV/HTLV-III lymphadenitis and immunological, clinical, and serological variables. The study group included 38 consecutive homosexual men with persistent generalized lymphadenopathy (PGL) in whom lymph node biopsy was performed. The histopathological lymph node changes were grouped into three stages. Opportunistic infections at the time of biopsy and their development during follow-up were significantly associated with stage III histology (follicular depletion). Analysis of blood from 10 patients with stage III histology revealed significantly (P less than 0.01) decreased proliferative responses of lymphocytes to mitogens and reduced absolute number of CD5+ and CD4+ lymphocytes compared with 17 patients with stage I histology (follicular hyperplasia), whereas patients with stage II histology (follicular involution) had intermediate values. The absolute number of CD8+ lymphocytes was increased in all three stages, as was IgG, while increase in IgM and IgA was restricted to stage III. No difference was observed between the different histopathological stages with respect to the specificity of the anti-LAV/HTLV-III antibody as measured by immunoblotting. In conclusion, the defects of lymphocytes from the blood of LAV/HTLV-III infected persons reflect alterations in secondary lymphoid tissue. Further, there is a close correlation between these alterations and the clinical status of the patients.