Immune deficiency predisposing to Epstein-Barr virus-induced lymphoproliferative diseases: the X-linked lymphoproliferative syndrome as a model

Bone marrow aplasia with prominent atypical plasmacytic proliferation preceding acute lymphoblastic leukemia

A two-year-old boy presented with pancytopenia. Bone marrow examination revealed an aplastic marrow with prominent immature plasma cell proliferation, which mimicked plasma cell leukemia. Immunohistochemistry, however, revealed a polyclonal population consistent with a reactive process, excluding plasma cell neoplasia. Administration of granulocyte-colony stimulating factor resulted in recovery of normal hematopoiesis with resolution of plasmacytosis. Seven months later, the patient had an elevated white blood cell count and bone marrow findings diagnostic of acute lymphoblastic leukemia. To the best of our knowledge this is the first reported case of bone marrow aplasia with prominent polyclonal plasmacytosis presenting as a prodrome of acute lymphoblastic leukemia in childhood.

Detection of Epstein-Barr virus DNA in sera from transplant recipients with lymphoproliferative disorders

Early diagnosis of Epstein-Barr Virus (EBV)-associated posttransplant lymphoproliferative disease (PTLD) is important because many patients respond to reduction in immunosuppression, especially if PTLD is detected at an early stage. Previous studies have found elevated EBV DNA levels in blood from patients with PTLD, but these assays required isolation of cellular blood fractions and quantitation. We evaluated the presence of cell-free EBV DNA in serum from solid-organ transplant recipients as a marker for PTLD. Five of 6 transplant recipients with histopathologically documented PTLD had EBV DNA detected in serum at the time of diagnosis (sensitivity = 83%), compared with 0 of 16 matched transplant recipients without PTLD (specificity = 100%) (P < 0.001 [Fisher's exact test]). Furthermore, EBV DNA was detected in serum 8 and 52 months prior to the diagnosis of PTLD in two of three patients for whom stored sera were analyzed. Detection of EBV DNA in serum appears to be a useful marker for the early detection of PTLD in solid-organ transplant recipients. Further studies to define the role of such assays in evaluating solid-organ transplant patients at risk for PTLD are warranted.

Selective compartmental dominance: an explanation for a noninfectious, multifactorial etiology for acquired immune deficiency syndrome (AIDS), and a rationale for ozone therapy and other immune modulating therapies

The most widely accepted etiological explanation for acquired immune deficiency syndrome (AIDS) currently invokes an infectious model involving the human immunodeficiency virus (HIV). Because this infectious model has failed to meet any conventional criteria for establishing microbial causation, this theory still relies on the high, though not perfect, statistical correlation linking presence of HIV antibodies with patients diagnosed with, and at risk for the syndrome. Many scientists and clinicians now doubt the HIV theory, though, and propose instead a multifactorial causation similar to that seen in cancer and heart disease. In order to discard the HIV model, however, it is necessary to explain the high statistical correlation mentioned above. Recent studies involving cellular mediated immunity and cytokine modulation may explain this statistical relationship without the need to invoke infectious causation, by suggesting certain functional characteristics and feedback loops in the immune system which the author calls selective compartmental dominance (SCD). SCD provides a model in which chronic dominance of the humoral immune compartment secondary to chronic high-dose antigenic challenge results in chronic suppression of the cellular immune compartment. This model predicts that even HIV-negative members of the risk groups are susceptible to AIDS, assigns no special causal role for HIV in AIDS, and suggests a rational course of nontoxic therapy that can potentially reverse cases in the earlier stages.

[Genetic predisposition to cancer]

This review focuses on the genetics of inborn predisposition to the development of cancer. The gene defects responsible for the majority of the most common syndromes of inherited predisposition to cancer have been deciphered during the last five years. These discoveries have shown that the genetics of most of these inherited forms of cancer is remarkably simple: the mechanism underlying the risk of cancer is precisely the one proposed by Knudson to explain the inherited forms of retinoblastoma. Only a small minority of the cancers are imputable to inherited mutations causing a very high risk of cancer. However, low penetrance susceptibility genes, mainly acting as environmental risk modifiers, are probably involved in the development of the majority of cancers. As much as possible, we will consider the immediate and long term possible repercussions on everyday medical practice of these advances in basic understanding of genetic cancer risks.

Giant cell formation in Hodgkin's disease

The identity of Reed-Sternberg cells in Hodgkin's disease has remained an unresolved issue, though many studies have addressed this question. Giant cells are usually formed either by endomitosis without cytoplasmic division or by cell fusion through cytokines or viruses. Growing evidence associates Epstein-Barr virus (EBV) with Hodgkin's disease, a major issue being whether EBV is a passenger virus or has an aetiological role. This communication describes experimental conditions enabling observation of giant cell cytogenesis from peripheral blood mononuclear cells in culture. Mononuclear cells were isolated from autologous peripheral blood and cocultured with a single-cell suspension obtained from Hodgkin's lymph nodes in a culture chamber where the two cell populations are isolated by a microporous membrane that allows only cytokines and viruses to pass through. Under these experimental conditions, giant cells are formed in the peripheral blood mononuclear cell fraction; some of them appear morphologically indistinguishable from Reed-Sternberg cells and their mononuclear variant, while others much resemble Langhans giant cells. Some of these giant cells are positive for EBV DNA by in situ hybridization. These results suggest that an EBV-dependent biological activity is responsible for giant cell cytogenesis originating from lymphocytes and monocytes, induced either by EBV and/or cytokines.

Primary central nervous system lymphoma

Primary central nervous system lymphomas (PCNSL) are uncommon neoplasms accounting for less than 2% of brain tumours. Their incidence appears to be increasing across a wide age range, in both immunocompetent and immunosuppressed populations. Particular risk groups include those with congenital and acquired immunodeficiencies and transplant recipients. The spread of the AIDS epidemic has seen large numbers of complicating PCNSL develop. Epstein-Barr virus infection appears to play a role in the development of these lymphomas in the immunosuppressed population. The aetiology of these tumours in the immunocompetent is uncertain. Their tendency to remain within the nervous system is not well understood but may be a function of CNS binding molecules carried by lymphocytes. Clinically PCNSL may present with a wide variety of signs and symptoms and has a capacity to mimic many other neurological conditions. Radiologically they appear as hyperdense homogenous deposits in subcortical white matter. Although most lesions are intermediate or high grade B cell lymphomas, T cell lymphomas are being recognised with increasing frequency. Immunohistochemistry and genotypic analysis have an important role in accurately characterising PCNSL, particularly in stereotactic biopsies. Involvement of multiple areas of the neuraxis, the eye and multiple intracranial sites can occur in the absence of obvious systemic lymphoma. The role of surgery in their treatment is uncertain. A combination of radiotherapy and chemotherapy can increase the length of survival. The prognosis, however, remains poor in comparison with nodal lymphomas, and particularly so in those with AIDS.

The X-linked lymphoproliferative disease: from autopsy toward cloning the gene 1975-1990

Although X-linked lymphoproliferative disease (XLP) is rare (1-2 males per 1 x 10(6)), it serves as a model for discerning diverse diseases caused by Epstein-Barr virus (EBV) ranging from agammaglobulinemia to fatal infectious mononucleosis following infection with the virus. The study of patients with XLP has also paved the way to understanding how EBV induce diseases in children with primary immunodeficiency diseases, organ transplant recipients, and those with acquired immunodeficiency syndrome. This review is dedicated to the memory of Gordon Vawter, M.D., who generously provided insights into the causes of pathogenesis of immune deficiency and lymphoproliferative disorders.

Genetically determined coincidence of Kaposi sarcoma and psoriasis in an HIV-negative patient after prednisolone treatment. Spontaneous regression 8 months after discontinuing therapy

We report the case of drug-induced, acrolocalized Kaposi sarcoma (KS), arising multicentrically in both palms and soles of a male patient who has had widespread psoriasis since 12 years of age. This 59-year-old man, of Mediterranean origin, was HIV antibody-negative and had received oral prednisolone treatment over 5 months for chronic obstructive lung disease (initial dose: 75 mg/d). Eight months after discontinuing oral treatment the KS nodules regressed spontaneously and finally disappeared completely without additional treatment. Light and electron microscopic investigations confirmed the diagnosis of KS, whereas laboratory tests excluded HIV infection and suggested mild immune dysfunction. The existence of HLA loci predisposing to KS and to psoriasis (A1, DR5, DR7, DR11) was characteristic for the simultaneous occurrence of these two diseases. This case report demonstrates the complex interrelationships between genetic predisposition, drugs leading to immune suppression, and the evolution of an unusual neoplasm.

What's new in primary central nervous system lymphomas?

Primary central nervous system lymphomas (CNSL) are uncommon neoplasms accounting for about 1% of primary brain tumors. Patients with congenital or acquired immunodeficiencies including AIDS patients and transplant recipients represent the main high-risk population for CNSL occurrence. An important point emerging from the literature is that CNSL incidence has dramatically increased during the last years not only in HIV infected patients by virtue of the AIDS epidemic spread, but also for unclear reasons in immunologically normal persons. Although c-myc oncogene activation and Epstein-Barr virus infection are considered to play a role in CNSL development, the peculiar tendency of these lymphomas to occur and remain inside the CNS is not well understood and may involve putative CNS binding molecules carried by lymphocytes. The clinical presentation is characterized by a great variety of neurological disorders. Radiological features consist of hyperdense homogeneous deposits within the subcortical white matter with a pattern of marked enhancement after injection of contrast material. The tumor masses are usually ill-defined and multicentric. Although all cytological types can be observed, the most common types belong to the high-grade category of non-Hodgkin's lymphoma. Monoclonal antibodies reactive with formalin-fixed, paraffin-embedded sections can be used in conjunction with stereotactic needle biopsy to provide accurate immunological characterization of CNSL. The large majority of CNSL is of B-cell origin but T-cell lymphomas seem at the present time less exceptional than previously thought. Although radiotherapy and chemotherapy can increase length of survival, the prognosis of CNS remains dramatically poor, the shortest survival being observed in AIDS patients.

Demonstration of Epstein-Barr virus in primary brain lymphoma by in situ DNA hybridisation in paraffin wax embedded tissue

Tumour tissue from 29 patients with primary brain lymphoma was reviewed to determine if there was an aetiological association between Epstein-Barr virus and polyclonal and monoclonal lymphoproliferations. The morphology and immunophenotype in 24 patients for whom paraffin wax embedded tissue was available were studied. A high grade pleomorphic tumour morphology with plasmacytoid features was seen in 13 tumours. Because of the large number of pleomorphic lymphomas, all tumours were examined for the presence of the Epstein-Barr virus genome using in situ DNA hybridisation. A panel of three biotinylated probes to different sequences in the Epstein-Barr virus genome was used. Positive hybridisation with one or more probes was shown in tumours from 11 patients. The remaining tumours gave no hybridisation signal. There was no correlation between positive hybridisation and morphological subtype or clinical outcome.

Morphologic and immunophenotypic characterization of primary brain lymphomas using paraffin-embedded tissue

Primary lymphomas of the brain constitute about 1% of all primary intracranial neoplasms, but recent studies suggest an increasing incidence. Most cases are associated with an immunosuppressed state. We reviewed 29 cases of primary brain lymphoma from the Yorkshire Health Authority Region between 1970 and 1988 and found a striking increase in incidence over this period. No overt evidence of immunosuppression was found in any case. All were non-Hodgkin's in type and were classified morphologically using Kiel criteria and immunophenotypically using a panel of antibodies. Cryo-preserved tissue was available in five cases for parallel immunophenotyping. The majority of tumours were high-grade lymphomas together with three of lymphoplasmacytoid type. Thirteen tumours showed a striking pleomorphic morphology with plasmacytoid features. A reactive, predominantly perivascular monomorphic T-cell population was seen in all tumours. Most tumours were of B-cell lineage. No cases of Hodgkin's disease, T-cell or histiocytic lymphoma were present. Light chain restriction was present in only 46% of cases. The results of tumour immunophenotyping on cryostat sections were comparable with those from paraffin blocks. Our study emphasizes the value of a panel of antibodies reactive in paraffin-embedded tissue, allowing simultaneous evaluation of morphology and immunophenotype, and suitable for small biopsies received from stereotactic procedures.

Induction of Epstein-Barr virus in B-lymphoblastoid cells by human immunodeficiency virus type 1

Individuals infected with the human immunodeficiency virus (HIV), the etiologic agent of acquired immunodeficiency syndrome (AIDS), often show symptoms associated with reactivation of Epstein-Barr virus (EBV). In this study, we show that exposure of EBV-positive B lymphocytes to HIV-1 in vitro induced the EBV replicative cycle in these cells, as evidenced by an increased proportion of cells expressing EBV early antigens (EA) and capsid antigens (VCA). Reactivation of EBV by HIV-1 appeared to be virus-dose-dependent and required virus penetration and expression in B cells. Although HIV-1 RNA was detected by in situ hybridization in the majority of HIV-1-infected B lymphocytes, induction of EA and VCA was transient and limited to less than 20% of the cell population. The tumor-promoting phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and HIV-1 acted synergistically and had similar kinetics in inducing the expression of EBV. Direct reactivation of EBV by HIV-1 may contribute to the role of EBV as a factor in the genesis of AIDS-related conditions.

Cyclosporine: a review and its specific use in liver transplantation

During the past decade, treatment with cyclosporine, an immunosuppressive agent, has contributed substantially to enhanced allograft and patient survival after liver transplantation. Currently, the 1-year survival rate after liver transplantation is more than 80% in major liver transplantation centers, in contrast with approximately 60% before the availability of cyclosporine. Its predominant immunologic effect is inhibition of lymphokine production and secretion by helper T cells. The use of cyclosporine, however, is associated with numerous adverse effects, the most important of which are nephrotoxicity, hypertension, neurotoxicity, opportunistic infections, and malignant lesions. Acute nephrotoxicity, hypertension, and neurotoxicity usually can be reversed by decreasing the dose of cyclosporine. Measurement of cyclosporine concentrations in the blood is essential for optimization of immunosuppressive therapy and prevention of toxicity.

Primary central nervous system lymphoma

Primary lymphoma of the central nervous system (CNS), including reticulum cell sarcoma, microglioma, and histiocytic lymphoma, represents less than 1% of all primary brain tumors. In the last 10 years, this tumor has tripled in frequency in the nonimmunosuppressed population. By 1991, the tumor will be the most common neurological neoplasm by virtue of the increase in sporadic occurrence and in the acquired immunodeficiency syndrome (AIDS) population. Three percent of AIDS patients will develop this tumor either prior to AIDS diagnosis or during their subsequent course. In addition to acquired immunosuppression, patients with inherited disorders (such as Wiskott-Aldrich syndrome, severe combined immunodeficiency, and X-linked immunodeficiency) and other acquired disorders of the immune system are predisposed to the development of CNS lymphoma. Immunological studies have suggested a role for Epstein-Barr virus in the production of this tumor. Although subtypes exist, non-Hodgkin's lymphoma of the CNS most commonly consists of histiocytic cells or large immunoblastic cells bearing B cell surface markers in close proximity to the lateral and third ventricles. Sixty percent of these deposits are multiple, and subarachnoid invasion is seen in one-quarter of patients. Vitreous involvement of the eye occurring prior to and during the course of CNS lymphoma has been noted in up to 25% of patients. The involvement of multiple areas of the neuraxis, the eye, and multiple intracranial sites often occurs in the absence of obvious systemic lymphoma. Therapeutic trials of brain radiation therapy are associated with median survivals of less than 1 year. Uniform complete responses of intracranial deposits are recorded following chemotherapy with high-dose intravenous methotrexate, CHOP (cyclophosphamide, hydroxydaunomycin/doxorubicin, Oncovin (vincristine), and prednisone), high-dose cytosine arabinoside, and intra-arterial methotrexate with barrier modification.

Antibody response to Epstein-Barr virus antigens in patients with chronic viral infection

We tested antibody titres against Epstein-Barr virus (EBV) antigens in patients suffering from chronic viral disease and compared them with those determined in sex- and age-matched healthy controls. Patient sera showed signs of active EBV infection [antibodies against early antigen (EA) and/or viral capsid antigen (VCA) in the IgM or IgA classes] significantly more frequently than the control group. Correspondingly, geometric mean titres (GMT) of antibodies against all viral antigens were elevated in the patients. The strongest association with EBV was observed in patients whose clinical symptoms closely resembled infectious mononucleosis: 92% of the subjects in this subgroup possessed anti-EA and 41 and 25% had IgM and IgA anti-VCA antibody, respectively. In patients with signs of lymphoproliferation only and in those suffering from frequent respiratory infections the association with EBV was less marked but still significant. Patients with transient defects in humoral and cellular immunity mounted higher titres against VCA in the IgG class than those without immune defects.

Microbial oncogenesis

For more than a century, medical investigators have sought to incriminate microorganisms in the cause of cancer. The first scientific evidence of such a relationship came in 1911, with the first successful induction of a tumor using a cell-free extract. Since that time, considerable data have accrued linking retroviruses, herpes viruses, the hepatitis B virus, papovaviruses, and adenoviruses to various malignant neoplasms. There is also increasing evidence that certain bacteria and parasites participate as cofactors in the development of some cancers. Although proof of cause-and-effect relationships has been difficult to obtain, there can be little doubt that microorganisms occasionally play pivotal roles in the origin of some cancers. Whether attempted intervention against these cancers is best directed against the oncogenic microorganisms themselves or against other environmental cofactors is not yet clear. Nevertheless, the successful application of tumor vaccines in the prevention of Marek's disease in chickens and in modifying the outcome of oncogenic herpesvirus infections in nonhuman primates offers hope of at least limited application of microbial vaccines in the prevention of human cancer.

Immunopathology of AIDS (acquired immune deficiency syndrome) observations in 75 patients with pre-AIDS and AIDS

Sequential changes in the morphology of immunocompetent and other organs, in the accompanying immunocytological and immunovirological measurements are described in 75 patients with lymphadenopathy syndrome and with AIDS. The data presented demonstrate a stepwise development of the disease from a hyperimmunization syndrome to T-cell immune deficiency. Excessive antigenic stimulation by a large number of infectious organisms or by transfusion of blood and blood products account for antigenic overloading and hyperimmunization. Among such infectious organisms are certain viruses which per se interfere with cells of the immune system as for instance Epstein-Barr virus, cytomegalovirus, and HTLV3. Developing immunological incompetence will favor the persistence of these and other infectious organisms enhancing the damage of the immune reactivity and finally allow lethal infections or malignant tumors to occur.

Role of Epstein-Barr virus in acquired immune deficiency syndrome

We have reviewed the biologic characteristics, immune responses, and diverse array of diseases occurring from Epstein-Barr virus infections in immune deficient patients. We have summarized possible roles of the virus in the risk groups for AIDS. Data is convincing that EBV is responsible for some of the cases of lymphadenomegaly and Burkitt-like, non-Hodgkin's lymphomas in patients with pre-AIDS and AIDS. A hypothesis has been proposed wherein EBV and other stimulants of B and T cells allow productive infection by the retrovirus and spread of HTLV-III throughout the helper T cell populations.

Burkitt's lymphoma in the Sudan

Burkitt's lymphoma is the commonest of the jaw tumours affecting children in some parts of the tropical Africa. In the Sudan, the tumour appears to be relatively uncommon and our study showed only 7 cases during a 5-year period from December 1975 through to December 1980. The clinical features, aetiology, histopathology and the treatment of the tumour are discussed and the literature briefly reviewed.

Characterization of the acquired immune deficiency syndrome at the cellular and molecular level

The acquired immunodeficiency syndrome (AIDS) is a new disease characterized by severe dysfunction of both the T cell and B cell systems, occurring in previously healthy individuals. Affected individuals may have recurrent and chronic opportunistic infections and/or Kaposi's sarcoma or other malignancy. Analysis of the cellular and subcellular components of immunity demonstrates a profound depression in the number and function of helper/inducer T cells bearing the OKT4 (Leu 3) differentiation antigen and a concomitant defect in the synthesis of the immuno-enhancing soluble growth factor, interleukin 2 (IL-2). Hypotheses to explain the etiology of the immunological dysfunction and implications for future therapy of AIDS are discussed.

Alpha interferon for induction of remission in hairy-cell leukemia

We treated seven patients who had progressive hairy-cell leukemia with daily doses of 3 million units of partially pure alpha (leukocyte) interferon by the intramuscular route. Three patients had a complete remission, and four had a partial remission, according to strict criteria for a response. After treatment, bone-marrow aspirates showed an absence of leukemia cells in three patients and 5 per cent or fewer in three others. Normalization of subnormal peripheral-blood values occurred in six of six patients with anemia, in seven of seven with granulocytopenia, and in four of four with thrombocytopenia. Remissions have been maintained for over 6 to over 10 months. Alpha interferon appears to be highly effective in patients with hairy-cell leukemia.

Immunological surveillance of tumors in the context of major histocompatibility complex restriction of T cell function

The immunological surveillance hypothesis was formulated prior to the realization of the fact that an individual's effector T cells generally only see neoantigen if it is appropriately presented in the context of self MHC glycoproteins. The biological consequence of this mechanism is that T lymphocytes are focused onto modified cell-surface rather than onto free antigen. The discovery of MHC-restricted T cell recognition, and the realization that T cell-mediated immunity is of prime importance in promoting recovery from infectious processes, has thus changed the whole emphasis of the surveillance argument. Though the immunological surveillance hypothesis generated considerable discussion and many good experiments, there is no point in continuing the debate in the intellectual context that seemed reasonable in 1970. It is now much more sensible to think of "natural surveillance" and "T cell surveillance," without excluding the probability that these two systems have elements in common. We can now see that T cell surveillance probably operates well in some situations, but is quite ineffective in many others. Part of the reason for this may be that the host response selects tumor clones that are modified so as to be no longer recognized by cytotoxic T cells. The possibility that this reflects changes in MHC phenotype has been investigated, and found to be the case, for some experimental tumors. In this regard, it is worth remembering that many "mutations" in MHC genes that completely change the spectrum of T cell recognition are serologically silent. The availability of molecular probes for investigating the status of MHC genes in tumor cells, together with the capacity to develop cloned T cell lines, monoclonal antibodies to putative tumor antigens, and cell lines transfected with genes coding for these molecules, indicates how T cell surveillance may profitably be explored further in both experimental and human situations.

Epstein-Barr virus-associated antibody pattern in untreated non-Hodgkin lymphoma patients. Relationship to clinical variables and lymphocyte functions

Sera from 296 unselected and untreated patients with non-Hodgkin lymphoma (NHL) classified according to the Rappaport and the Kiel systems were analyzed for antibodies to Epstein-Barr virus (EBV). The aim of the study was to determine whether antibody spectra and titers to EBV-coded antigens correlated to clinical and immunological variables and whether the titers were of any prognostic significance. Increased antibody titers to EB viral capsid antigen (VCA) and slightly raised titers to early antigens (EA) of the diffuse (D) and restricted (R) types were noted frequently. Anti-VCA antibody titers correlated to clinical stage and age of the patients but not to histological subgroups according to the Rappaport or the Kiel classification systems. However, anti-VCA titers greater than or equal to 1:2560 were seen only in diffuse lymphomas according to the Rappaport and in non-follicle cell-derived lymphomas according to the Kiel classifications. Patients with complement-receptor-positive diffuse lymphomas had higher anti-VCA titers than complement-receptor-positive nodular cases. Anti-VCA titers also correlated positively to serum IgG levels (p less than 0.01). Total number of lymphocytes separated from peripheral blood and mitogen induced (ConA, PWM) DNA synthesis were recorded before treatment in 56 of the patients. The patients exhibited a significant lymphocytopenia as well as a significantly reduced lymphocyte response to mitogens (p less than 0.001) compared to healthy controls. Elevated anti-VCA titers and anti-EA titers correlated to a good mitogen-induced lymphocyte response (p less than 0.05). Only anti-D 1:40 at diagnosis predicted a poor prognosis.

Frequencies of HLA and Gm immunogenetic markers in Kaposi's sarcoma

An outbreak of Kaposi's sarcoma in homosexual men has recently been observed in New York and California which differs from the "classic" North American disease with regard to younger age of onset and clinical prognosis. Although the exact mechanism for initiation of either disease is still unknown, a viral mechanism has been suggested in both cases. In order to investigate the possible role of HLA-associated variations in genetic susceptibility, 39 patients with histologically documented Kaposi's sarcoma were typed for HLA-A,B,C antigens. Most of these patients were also typed for HLA-DR antigens and for Gm allotypes. A significant increase in DR5 occurred in both groups. Decreases in B8 and DR3 and an increase in homozygosity for the Gm haplotype 3;5,13 were also noted. These results suggest that HLA and Gm linked immune response factors may play a role in the induction of both these forms of the disease.

Evolution of infectious mononucleosis into Epstein-Barr virus carrying monoclonal malignant lymphoma

A monoclonal malignant lymphoma was diagnosed in a 30-month-old Japanese boy, who, since the age of 12 months, had had chronic, recurrent infectious mononucleosis manifested by repeated episodes of severe cough and high fever accompanied by marked lymphadenopathy and hepatosplenomegaly and high serum Epstein-Barr virus (EBV) antibody titres. The diagnosis of Burkitt's lymphoma was made when a cervical lymph-node biopsy specimen revealed massive proliferation of immature B-cells with starry-sky histiocytes. These lymph-node cells were characterised by a translocation between chromosomes 10 and 17. There were approximately 9 EBV genome-equivalents per cell. Most cells were positive for nuclear antigen (EBNA); early antigen (EA) and viral capsid antigen (VCA) were also detected. The presence of EBV was supported by finding that the cell-free lymph-node extract transformed cord-blood lymphocytes into EBNA-positive blast cells. The proportion of EA-positive and VCA-positive cells increased rapidly in culture for 24 h, then the positive cells degenerated rapidly and completely. The cells also contained numerous herpes-type virus particles. The child improved considerably with cytostatic treatment and has been in remission for 2 years.