Follicular involution in HIV lymphadenopathy. A morphometric study

Lymph node biopsies from 75 HIV infected patients (71 homo- and bisexual men, 3 hemophiliacs and 1 woman) were studied using immunohistochemical methods with monoclonal antibodies (Mabs) against B lymphocytes, subsets of T lymphocytes, follicular dendritic cells (FDC) and HIV gag proteins p24 and p18. Histopathological changes were classified as follicular hyperplasia (FH), fragmentation (FF), atrophy (FA) and depletion (FD). Immunohistochemical stainings were quantified with the help of an Image Quantifier (IQ) and the reactivity for respective Mab-defined antigen was related quantitatively to other antigens and histopathological changes. Such measurements showed an increase in FDC in biopsies with FH and FF histology and a decrease in FA and FD cases in comparison with cases with non-HIV related lymphadenopathy. In addition it was found that the decrease in FDC was correlated with an increase in CD8+ within the follicles. Double immunostainings for p24 and various cellular markers showed that p24 was predominantly associated with follicular dendritic cells. Essentially the same findings were observed in the lymph nodes irrespective of risk group. Possible mechanisms involved in follicular involution in HIV-related lymphadenopathy are discussed.

AIDS-Kaposi's sarcoma-derived cells express cytokines with autocrine and paracrine growth effects

When grown in vitro, cells from Kaposi's sarcoma lesions of AIDS patients (AIDS-KS cells) constitutively release several growth promoting activities. When inoculated into nude mice, the AIDS-KS cells induce a KS-like lesion of mouse origin. Here it is shown that the AIDS-KS cells express messenger RNA for a complex mixture of cytokines that correlate with several of the biological activities of these cells. Basic fibroblast growth factor, which is a potent angiogenic factor, and interleukin-1 messenger RNAs are expressed at very high levels and seem to account for a large proportion of the activities, since their corresponding proteins are released in biologically active form into the culture media where they induce autocrine and paracrine growth effects.

Cell association of HIV in AIDS-related encephalopathy and dementia

The presence of HIV gag and env proteins (HIV Ag) and virus replicating cells was studied by immunohistochemistry and in situ hybridization, respectively, in brain specimens from five HIV infected patients. HIV antigens were detected in 3 of 5 brains in micronodular areas characterized by increased cellularity and the presence of multinuclear giant cells. By double immunostaining, HIV Ag positive cells were shown to express markers common to macrophages and microglia i.e. Leu M5+, My4+, HLA-Dr+, RCA-1+, and to a lesser extent CD4+ (Leu3+). Another macrophage specific marker, KiM6, was found only on HIV+ cells in HIV infected specimens and not in uninfected, control brains. Medium-sized, virus replicating cells were found exclusively in micronodular areas, but in much smaller quantities than HIV Ag+ cells. Our observations provide further evidence to support the hypothesis that macrophages play an important role in CNS infection by HIV and additionally support the concept that reactive microglial originate from activated macrophages infiltrating the brain. Both direct effects of viral components and cell mediated reactions can be implicated from our findings as mechanisms involved in the pathogenesis of the CNS lesions.

Flow cytometric DNA analysis: a prognostic tool in non-Hodgkin's lymphoma

Surgical biopsies from 234 untreated patients with non-Hodgkin's lymphoma (NHL), classified according to the Kiel nomenclature, were analysed with respect to proliferative activity (S-phase) and DNA content by flow cytofluorometric (FCF-DNA) analysis. The percentage of cells in S-phase was significantly higher in lymphomas of high compared to low grade NHL (p less than 0.001). Patients with lymphomas of high grade histology and low S-phase values (less than 5.6%) achieved complete remission (CR) more often (p less than 0.05) and survived significantly longer than those with high S-phase values (p less than 0.05). In the low grade NHL group the S-phase value did not correlate to response. S-phase correlated to survival for patients with the lymphocytic (CLL & IC) (p less than 0.05) and follicle center cell (FCC) derived (p less than 0.01) but not in blastic (LB, IB, Burkitt) NHL. DNA-aneuploidy was associated with poor response to therapy and shorter CR duration in low grade NHL (p less than 0.05 for both). However, the degree of DNA-ploidy (neardiploid or aneuploid) did not correlate to survival in any of the NHL groups analysed (high- or low grade, lymphocytic, FCC derived or blastic). The Cox regression analysis indicated that the S-phase value was a stronger predictor of survival than histopathology, stage or age, especially in low grade NHL. These results suggest that S-phase analysis should be included in the clinical evaluation of NHL patients as a prognostic indicator.

Prognostic significance of immunoglobulin isotype expression in B-cell non-Hodgkin's lymphoma

Lymph node biopsies from 170 patients with untreated non-Hodgkin's lymphomas (NHL) of B-cell type were immunophenotyped and analyzed for the Ig heavy and light chain isotypes and their relation to prognosis. IgM alone was more frequently seen in high grade (53%) compared to low grade (20%) NHL. In contrast, IgM/IgD isotypes were more frequent in low grade (47%) than in high grade NHL (20%). IgG or IgA heavy chain, alone or in combination with other heavy chain isotypes, were expressed with the same frequencies in both low (32%) and high (27%) grade NHL. Clonally restricted kappa light chain expression was noted in 64% of low grade and 66% of high grade NHL patients. Only in chronic lymphocytic leukemia (CLL) and immunocytoma (IC) was a shorter survival time noted for patients with tumors expressing IgG and/or IgA heavy chains compared to those expressing IgM or IgM/IgD (P less than 0.001). This difference was not seen as being low grade follicle center cell-derived (FCC) or high grade NHL. The expression of kappa light chains on the tumor cells was associated with a significantly longer survival in CLL and IC patients only (P less than 0.01).

Utilization of human hematopoietic cell lines for the propagation and characterization of HBLV (human herpesvirus 6)

Details of the productive infection of established human cell lines of diverse origin by HBLV (also designated Human Herpesvirus 6) are described in this report. The infection and replication of HBLV in several T and B lymphoid and other cell lines was observed by electron microscopic examination, by the detection of viral antigen expression by indirect immunofluorescence assay (IFA) and by the presence of HBLV DNA by Southern blot hybridization. Several of these cell lines produced large amounts of virus. For this reason and because of the absence of other human herpesviruses, these lines have provided a valuable resource for the preparation of reagents and the development of assays for the detection and characterization of HBLV. The isolation and characterization of new HBLV isolates from patients with chronic fatigue syndrome were also facilitated by using some of the cell lines reported here. The host range of HBLV in established cell lines, therefore, does not appear to be limited to the B lymphocytes, as initially suggested by in vivo studies. The infection of T and B lymphocytes, megakaryocytes and neuronal cells in vitro suggests a need for the evaluation of diverse hematological and neurological disorders to shed light on a possible HBLV involvement.

B-cell compartment in the thymus of patients with myasthenia gravis and control subjects

An increased number of CD19, 20, and 22 positive B cells, compared to the number of Ig-positive cells, is regularly found in the thymic medulla of normal thymus, suggesting that a B-cell population normally resides in thymic medulla that lacks Ig expression. However, some of the CD20-positive cells seem to co-express keratin and MR19, suggesting an epithelial origin. The medullary B cells found in normal thymus could be precursors of the tumor cells in "mediastinal clear cell lymphomas of B-cell type." In follicular hyperplasia in MG, the medullary epithelial network is deformed and partly destroyed, and the interlobular/perivascular spaces are expanded. Follicles with follicular dendritic cells are found in both interlobular/perivascular spaces and "punched out" lesions in the medullary epithelium. The B cells are greatly increased in MG thymuses compared with control thymuses. These cells are found mainly in the follicles, but they are also dispersed in the medulla and the interlobular/perivascular spaces. The immunophenotype and distribution of B and T cells as well as the follicular dendritic cells in the hyperplastic follicles are similar to those of reactive follicles in lymph nodes. Our findings are consistent with the contention that in MG there is an autoimmune activation of B cells that normally reside in the thymic medulla. This activation leads initially to follicular hyperplasia in the medullary epithelium with destruction of medullary epithelial cells. The prolonged immune reaction in the autoimmune process induces a fibronectin-rich stroma formation and increased vascularization. The result is a remodeling of the thymic architecture with expansion of the perivascular/interlobular spaces replacing the destroyed medulla.

Kaposi's sarcoma cells: long-term culture with growth factor from retrovirus-infected CD4+ T cells

Studies of the biology and pathogenesis of Kaposi's sarcoma (KS) have been hampered by the inability to maintain long-term cultures of KS cells in vitro. In this study AIDS-KS-derived cells with characteristic spindle-like morphology were cultured with a growth factor (or factors) released by CD4+ T lymphocytes infected with human T-lymphotropic virus type I or II (HTLV-I or HTLV-II) or with human immunodeficiency virus type 1 or 2 (HIV-1 or HIV-2). Medium conditioned by HTLV-II-infected, transformed lines of T cells (HTLV-II CM) contained large amounts of this growth activity and also supported the temporary growth of normal vascular endothelial cells, but not fibroblasts. Interleukin-1 and tumor necrosis factor-alpha stimulated the growth of the KS-derived cells, but the growth was only transient and these could be distinguished from that in HTLV-II CM. Other known endothelial cell growth promoting factors, such as acidic and basic fibroblast growth factors and epidermal growth factor, did not support the long-term growth of the AIDS-KS cells. The factor released by CD4+ T cells infected with human retroviruses should prove useful in studies of the pathogenesis of KS.

Angiogenic properties of Kaposi's sarcoma-derived cells after long-term culture in vitro

Cells derived from lung biopsies and pleural effusions from AIDS patients with Kaposi's sarcoma (KS) of the lungs were established in long-term culture with the aid of conditioned medium from HTLV-II-transformed T cells (HTLV-II CM). These AIDS-KS cells were similar to the so-called spindle cells in KS lesions and had some of their features. They produced factors that supported their own growth (autocrine) and the growth of other cells (paracrine), including umbilical vein endothelium and fibroblasts. That the AIDS-KS cells also expressed potent angiogenic activity was demonstrated by the chorioallantoic membrane assay and by subcutaneous inoculation of AIDS-KS cells into nude mice, which resulted in the development of angiogenic lesions composed of mouse cells and showing histological features similar to those of human KS lesions. These data suggest that AIDS-associated KS and possibly other types of KS may be initiated by signals that induce the growth of particular cells (spindle cells of lymphatic or vascular origin) and the expression of autocrine and paracrine activities.

IgG antibodies to human herpesvirus-6 in children and adults and in primary Epstein-Barr virus infections and cytomegalovirus infections [corrected]

Antibody titers against human herpesvirus-6 (HHV-6) were determined in 80 healthy adults and 100 children and teenagers from Sweden to gain information on the role of the virus and its epidemiology. Based on a positive immunofluorescence titer of 1:10 and above, about 85% of the adults and children were seropositive with 60% seropositivity of children below age one year. Titers were generally higher in patients with simultaneous EBV or CMV infection, yet crossreactivity appeared essentially no problem. HHV-6 thus is ubiquitous like other herpesviruses. Primary infection seems to occur early in life, and reactivation or delayed primary infection may be associated with a variety of disorders.

Human herpesvirus-6 (HHV-6, HBLV) in sarcoidosis and lymphoproliferative disorders

Serologic studies were done to estimate the antibody prevalence against human herpesvirus 6 (HHV-6) in patients with malignant lymphomas, Sjögren's syndrome and sarcoidosis. Serologic studies showed IgG antibody titers against HHV-6 in up to 41% of patients with sarcoidosis, 50-70% with malignant lymphomas and in 36% with Sjögren's syndrome. In situ hybridization on lymph node biopsies was positive for HHV-6 genome in 1 out of 5 sarcoidosis lymph nodes.

Clinical effects of monoclonal antibodies (MAb 17-1A) in patients with metastatic colorectal carcinomas

Ten patients with metastatic colorectal carcinoma were treated with MAb 17-1A (IgG2A). Before infusion, MAb was incubated in vitro with isolated autologous blood mononuclear cells. Treatment was given in repeated courses (2-4 times) to a maximum dose of 1000 mg of MAb 17-1A. One patient achieved a clinical complete remission, two patients had a minor response and one patient had stable disease for 5 months. The median survival for the four responders was 19 months compared to 7 months for the six non-responders. Therapy was well tolerated. In this series, 32 infusions of MAb 17-1A were given. The serum half-life of MAb 17-1A was approximately 22 hours. All patients developed anti-mouse antibodies of both IgG and IgM classes. No relation between adverse reactions and anti-mouse antibodies was seen. At 3 occasions allergic reactions were noted. Skin test with MAb 17-1A seems to reliably predict for allergic reactions.

Buoyant density characterization of neoplastic cell populations in patients with chronic B-lymphocytic leukemia

Leukemic cells from a series of patients with chronic B-lymphocytic leukemia (CLL) were analyzed for their buoyant density on discontinuous Percoll gradients. The density profile varied markedly between different patients and also between samples from different body compartments within the same patient. A good correlation was observed between buoyant density and maturation stage of the leukemic clones as judged by Ig-expression and their reactivity with a panel of monoclonal antibodies. Phorbol-ester-induced changes in the leukemic cells were found to be accompanied by a general decrease in their buoyant density. No correlation between density and clinical parameters such as cell counts, clinical stage and survival could be noted. Buoyant density characterization of leukemic B-cell populations is seen as a useful, rapid and simple marker of compartmentalization within the B-lymphocyte maturation spectrum but its clinical relevance remains to be established.

Immunohistochemical monitoring of metastatic colorectal carcinoma in patients treated with monoclonal antibodies (MAb 17-1A)

A therapeutic trial using repeated doses of a mouse monoclonal antibody against the tumor-associated antigen (TAA) CO17-1A in metastatic colorectal carcinomas was carried out. Metastatic lesions sampled by repeated thick needle (1.2 mm) biopsies during therapy were examined immunohistochemically for the presence of various TAAs, mouse IgG, complement, and infiltrating leukocytes. The CO17-1A was consistently expressed in all cases along the basement membrane of tumor glands and could only be demonstrated on cryostat sections whereas the TAAs GICA19-9, GA73-3, and Br55-2 were also visualized in B5-fixed paraffin-embedded biopsies. The CO17-1A and GA73-3 were predominantly present at the basal region in contrast to the GICA 19-9 and Br55-2 which were predominant at the luminal and the apical region of the tumor glands. Antigenic modulation was not seen either after 24-72 h or during prolonged treatment. In all cases the infused mouse IgG was detected, from 24 h after infusion up to 6-8 weeks, mainly along the basal region of tumor glands. In 13/14 posttreatment biopsies, complement factor C3 was found at the same sites as mouse IgG. In 6 out of 9 posttreatment biopsies an increase in mononuclear cells (monocytes, natural killer (NK) cells and/or T cells) was observed. Monocytes were close to the tumor cells whereas NK cells and T cells were predominantly scattered in the stroma.

Ultrastructural characterization of a new human B lymphotropic DNA virus (human herpesvirus 6) isolated from patients with lymphoproliferative disease

A new DNA virus, designated "human B lymphotropic virus" or "human herpesvirus 6" (HBLV), has been isolated from the peripheral blood leukocytes of patients with various lymphoproliferative disorders, in some instances also associated with human immunodeficiency virus (HIV-1) infection. HBLV, propagated in vitro in human cord blood lymphocytes, was found to be ultrastructurally similar to members of the herpesvirus family. It is an enveloped virus with an icosahedral nucleocapsid made up of 162 capsomeres. Unenveloped nucleocapsids in the cytoplasm wee always coated with a tegument, a feature also described for human cytomegalovirus (HCMV). However, the nucleoprotein core of HBLV does not have the beaded appearance as that of HCMV, nor do HBLV-infected cells contain the skein-like structure. Immune electron microscopy demonstrated the presence of specific antibodies to viral envelope and internal antigens in sera of infected patients, indicating that this virus is a possible human pathogen. These and previously reported characteristics are consistent with the HBLV being a new and unique DNA virus morphologically belonging to the herpesvirus family.

Quantification of CD8-positive lymphocytes in lymph node follicles from HIV-infected male homosexuals and controls

The number of CD8-positive cells in follicular centres of hyperplastic lymph nodes from 20 Danish and Swedish homosexual men with persistent generalized lymphadenopathy and 43 control patients were enumerated in frozen tissue sections immunostained with monoclonal antibody reactive with the CD8-antigen ("cytotoxic-suppressor" T-cell antigen). All the homosexuals were seropositive for HIV and histology showed changes characteristic of the early stage of HIV lymphadenitis. A significant increase (p much less than 0.001) of CD8-positive cells was demonstrated (mean 1,307 per mm2 follicular centre, SD 639) in HIV-related lymphadenopathy compared with the controls (mean 161 CD8-positive cells per mm2 follicular centre, SD 169). The results of this study show that the immunohistological demonstration of a significant increase of CD8-positive cells in the follicles of hyperplastic lymph nodes is suggestive of HIV-related lymphadenopathy.

Blood clonal B cell excess (CBE) at diagnosis in patients with non-Hodgkin lymphoma (NHL). Relation to clinical stage, histopathology and response to treatment

Untreated non-leukemic (lymphocytes less than or equal to 4.0 X 10(9)/l) patients with non-Hodgkin lymphoma (NHL) of B cell type often show an excess of B cells in peripheral blood bearing the same light chain isotype as the lymph node tumor cells which may indicate a leukemic spread of the disease. The ratio between kappa- and lambda-bearing lymphocytes (normal range 1.0-3.3) was studied to evaluate the prognostic significance of clonal B cell excess (CBE) at diagnosis in 110 NHL patients. In total 43% had a CBE in peripheral blood. Fifty-two per cent of the patients in clinically advanced stages had CBE and 30% of the patients in stages I and II. CBE was detected in 49% of all patients with low-grade malignant lymphoma and in 32% with high-grade malignancy. Patients with a normal kappa:lambda ratio at diagnosis entered complete remission more often than those with CBE (P less than 0.01). In patients with high-grade but not with low-grade malignant lymphomas remission duration was longer for those with normal kappa:lambda distribution than for the patients with an abnormal ratio (P less than 0.01). Survival was not statistically significantly influenced.

Histopathology and immunohistology of HTLV-III/LAV related lymphadenopathy and AIDS

Fifty-nine lymph node biopsies from homosexual men with serum antibodies to HTLV-III/LAV were the subject of a detailed histopathological and immunohistochemical study. The histological findings were correlated to the patients clinical status, and the T4/T8 ratios in blood and lymph nodes. Four histological patterns predominated and were defined as follicular hyperplasia (FH), follicular fragmentation (FF), follicular atrophy (FA), and follicular depletion (FD). Immunocytochemical studies indicated that destruction of follicular dendritic cells is related to the initiation of follicular involution from FH to FF, but the possible role of follicular infiltrating T-cells cannot be excluded. Marked individual variations in lymph node angiogenesis increasing during involution were observed, which suggests that the degree of angiogenic host response may predispose for evolution of Kaposi's sarcoma. The majority of the patients with the clinical diagnosis of persistent generalized lymphadenopathy (PGL) were morphologically staged as FH or FF (89%), whereas most of the AIDS patients showed lymph node changes compatible with FA and FD (89%). Patients with AIDS-related complex (ARC) had a wider spectrum of morphological lymph node changes but a majority of cases (62%) were also classified as FA or FD. Clinical follow-up showed progression from PGL to ARC in seven of 21 cases with the FF pattern and only in three of 19 cases with FH, indicating a possible prognostic value in differentiating between FH and FF. Three cases with FD and one with FA progressed to AIDS during the time of observation. T4/T8 ratios in blood and lymph nodes were significantly lower in patients with FD histology compared to patients of the other histological groups. At autopsy, all AIDS cases showed the FD pattern of lymphadenopathy. Autopsy findings in seven patients emphasized the importance of post-mortem studies in clarifying the spectrum of opportunistic diseases, including tumors which afflict the AIDS patients.

Unmasking antigen determinants in amyloid

Rehydrated paraffin sections of formalin-fixed, amyloid-containing tissues were treated with denaturing agents (guanidine and urea) and reducing agents (DDT and mercaptoethanol) before immunostaining, in an attempt to expose antigenic determinants hidden in the rigid structure of amyloid fibrils. Pre-treatment overnight with 6 M guanidine or urea was found beneficial, especially in specimens from familial amyloid polyneuropathy of the Portuguese type. Addition of reducing agents had no major effect. Modifications of this method may be useful in unmasking other antigens that are polymerized or considered destroyed by fixation and paraffin embedding.

HTLV-III expression in infected lymph nodes and relevance to pathogenesis of lymphadenopathy

In situ hybridization with a 35S-labeled probe of cryosections from 14 lymph nodes of HTLV-III/LAV-seropositive individuals with lymphadenopathy showed the presence of rare cells containing HTLV-III RNA at levels consistent with virus replication. Positive cells were observed at a frequency of only 1-10 per section. In all lymph nodes studied, including those showing follicular hyperplasia or involution, most of the cells expressing viral RNA were present in the follicular areas. Only a minority of such cells were found outside the follicles. The nature of the follicular, virus-replicating cells was not evident from the processed cryosections. After prolonged autoradiography, another pattern of hybridization was observed, suggesting low levels of viral RNA diffusely distributed throughout most, but not all, follicles. This may represent extracellular virus and/or virus-antibody complexes, but was not consistent with intracellular viral RNA or phagocytosed virus particles. Comparison of hybridization levels in relation to histology suggested a decrease in both the number of HTLV-III replicating cells as well as in the diffusely distributed viral RNA with progression of follicular involution. Our observations indicate that in HTLV-III-infected subjects, lymph node follicles are an important site of virus replication and trapping, suggesting a decisive role of the virus in the characteristic reactive and cytopathogenic changes of HTLV-III-associated lymphadenopathy.