NIH conference. Molecular genetic analysis of human lymphoid neoplasms. Immunoglobulin genes and the c-myc oncogene

Natural killer-type receptors for HLA class I antigens are clonally expressed in lymphoproliferative disorders of natural killer and T-cell type

In recent years, natural killer (NK) cells, as well as subpopulations of T cells, have been found to express diverse NK receptors (NKRs) for HLA class I molecules. We have characterized NKR phenotypes in lymphoproliferative disorders of NK or T-cell type. Peripheral blood of patients with lymphoproliferative disorders (n = 9) was analysed by multiparametric immunofluorescence flow cytometry with eight different antibodies against NKRs. Abnormal neoplastic cell populations from different types of NK or T-cell lymphoproliferative disorders lacked diversity in their NKR repertoires, i.e. all or none of the abnormal cells expressed individual NKRs and this expression occurred at single levels of intensity. This pattern of expression was specific for lymphoproliferative disorders as these resticted NKR repertoires were not found either in healthy donors (n = 9) or in patients with viral or autoimmune disease (n = 5). We conclude that NKRs are clonally expressed in lymphoproliferative disorders of NK or T-cell origin. NKR repertoires may represent a novel tool in diagnosing clonal disorders of NK and T-cell type.

Urine free light chains in SLE: clonal markers of B-cell activity and potential link to in vivo secreted Ig

As a marker of in vivo B-cell activity, urine levels of free light chain (FLC) were measured twice weekly by radioimmunoassay (RIA) and correlated with disease activity over periods of 5-10 months in seven patients with systemic lupus erythematosus (SLE). In addition, RIA-measured urine albumin was used to track glomerular injury, and alpha1-microglobulin (alpha1-M) levels, 28- to 32-kDa protein, provided control measurements on excretion of low-molecular-weight proteins. As controls, urine FLC levels were obtained from healthy normals and in subjects with acute pharyngitis, sickle-cell anemia, and acute sepsis or pneumonia. The control results showed that with acute sepsis/pneumonia had marked increases in urine FLC, while pharyngitis and sickle-cell controls had normal FLC levels. In SLE, active patients receiving intravenous cyclophosphamide and high-dose steroids exhibited highly increased urine FLC that fluctuated widely during therapy and fell to normal range levels with disease remission. During active SLE, urine albumin often was increased, while alpha1-M levels remained in normal range. In contrast to the increased FLC of active disease, inactive patients on low-dose maintenance therapy had predominantly normal FLC levels throughout the collection period. These results support our hypothesis that longitudinal levels of urine FLC can be used to track disease-related B-cell activity in SLE. Furthermore, we suggest that the urine FLC of active SLE would share LC idiotype with the clonal associated in vivo secreted Ig, and thus permit the identification of these antibodies that are targeted to the culprit immunogen(s) responsible for the pathogenesis of SLE.

Genetic toxicology data in the evaluation of potential human environmental carcinogens

In 1969, the International Agency for Research on Cancer (IARC) initiated the Monographs Programme to evaluate the carcinogenic risk of chemicals to humans. Results from short-term mutagenicity tests were first included in the IARC Monographs in the mid-1970s based on the observation that most carcinogens are also mutagens, although not all mutagens are carcinogens. Experimental evidence at that time showed a strong correlation between mutagenicity and carcinogenicity and indicated that short-term mutagenicity tests are useful for predicting carcinogenicity. Although the strength of these correlations has diminished over the past 20 years with the identification of putative nongenotoxic carcinogens, such tests provide vital information for identifying potential human carcinogens and understanding mechanisms of carcinogenesis. The short-term test results for agents compiled in the EPA/IARC Genetic Activity Profile (GAP) database over nearly 15 years are summarized and reviewed here with regard to their IARC carcinogenicity classifications. The evidence of mutagenicity or nonmutagenicity based on a 'defining set' of test results from three genetic endpoints (gene mutation, chromosomal aberrations, and aneuploidy) is examined. Recommendations are made for assessing chemicals based on the strength of evidence from short-term tests, and the implications of this approach in identifying mutational mechanisms of carcinogenesis are discussed. The role of short-term test data in influencing the overall classification of specific compounds in recent Monograph volumes is discussed, particularly with reference to studies in human populations. Ethylene oxide is cited as an example.

Fluorescence in situ hybridization analysis shows the frequent occurrence of 14q32.3 rearrangements with involvement of immunoglobulin switch regions in myeloma cell lines

In many B-cell malignancies, 14q32.3 chromosomal rearrangements involving the immunoglobulin heavy chain (IgH) locus have been shown to be pathognomonic for the disease. Although in myeloma heterogeneous and complex karyotypes are found, 14q32.3 translocations are prominent. However, owing to the telomeric position of the IgH locus, 14q32.3 translocations may be easily missed. We established fluorescence in situ hybridization (FISH) assays on chromosomes and DNA fibers to determine both the occurrence of 14q32.3 rearrangements in myeloma cell lines and the precise localization of the breakpoints in the IgH locus. Our results show that 14q32.3 chromosomal rearrangements are present in almost every myeloma cell line analyzed (17 of 19, 89%). Breakpoint analysis of the lines harboring one or more 14q32.3 rearrangements with the use of fiber-FISH revealed the involvement of switch regions in the IgH locus in 11 of 17 cell lines. Remarkably, pseudogamma genes without switch regions were involved in 3 of 17 cell lines, all derived from IgA myelomas. Three of 17 cell lines contained breakpoints outside a switch or immunoglobulin heavy chain constant region. The almost ubiquitous presence of 14q32.3 rearrangements suggests an obligatory role in the development of myeloma. The high incidence of breakpoints involving switch regions indicates an oncogenic event in a late stage of B-cell differentiation.

Chronic lymphoid leukemias: recent advances in biology and therapy

There exists a wide variety of lymphoid leukemias derived from B and T lymphocytes. These diseases have distinct immunologic and biologic features as well as varied responses to therapeutics. The most common lymphoid leukemia is chronic lymphocytic leukemia (CLL) which is a clonal proliferation of a subset of B cells expressing the CD5 antigen. Prolymphocytic leukemia is usually derived from B cells and shares some features with CLL but is clearly a distinct entity. Hairy-cell leukemia is a B cell malignancy that is uniquely responsive to a variety of biologic and chemotherapeutic agents. Waldenström's macroglobulinemia is a B cell malignancy that secretes immunoglobulin M (IgM) and may present with the hyperviscosity syndrome. Other B cell malignancies that less commonly present as leukemias include non-Hodgkin's lymphomas such as follicular lymphoma or mantle zone lymphoma. Multiple myeloma may rarely present or evolve into a plasma cell leukemia, typically in far advanced disease. T cell malignancies that may present as chronic lymphoid leukemias, and in the past have often been referred to as T cell chronic lymphocytic leukemia, are large granular lymphocytic leukemia, adult T cell leukemia/lymphoma, Sézary cell leukemia and rare cases of non-Hodgkin's lymphoma that are T cell derived and may present or evolve into a leukemic phase. There is also a rare T cell counterpart of prolymphocytic leukemia. Distinguishing these diseases is critical for optimal care of these patients.

Bronchoalveolar lavage fluid profiles in sarcoidosis, tuberculosis, and non-Hodgkin's and Hodgkin's disease. An evaluation of differences

The aim of this study was to identify characteristic features in bronchoalveolar lavage fluid (BALF) samples of patients with tuberculosis, non-Hodgkin's or Hodgkin's disease and to investigate whether these differences facilitate the distinction of those disorders from sarcoidosis presenting with a similar clinical picture. Nonsmoker patients with histologically verified sarcoidosis (n = 29), tuberculosis (n = 6) proven by positive culture, non-Hodgkin's disease, (n = 6) or Hodgkin's disease (n = 7), both histologically verified, were investigated by BAL. A control group consisted of subjects without any pulmonary history. The presence of CD4+ and CD8+ T lymphocytes, as well as the CD4/CD8 ratio in BALF, aided in the differentiation between the various groups. Patients with malignant lymphomas had the lowest CD4/CD8 ratio in BALF, as well as in peripheral blood, and occasionally, plasma cells were present in BALF samples. The most important feature of BALF analysis in tuberculosis was detection of the causal microbial agent. In conclusion, although malignant lymphomas and tuberculosis require histologic evaluation and a positive culture, respectively, for diagnosis, BALF analysis may be of additional value in distinguishing those disorders from sarcoidosis.

p53, c-myc p62 and proliferating cell nuclear antigen (PCNA) expression in non-Hodgkin's lymphomas

AIMS

To investigate the immunohistochemical expression of p53 protein in non-Hodgkin's lymphomas (NHL) and its relation to that of c-myc p62 oncoprotein and proliferating cell nuclear antigen (PCNA).

METHODS

Paraffin wax embedded tissue from 90 non-Hodgkin's lymphomas (72 B cell and 18 T cell) was stained immunohistochemically for p53 protein, c-myc p62 oncoprotein, and PCNA using the monoclonal antibodies DO7, c-myc 1-9 E10, and PC-10, respectively.

RESULTS

Of the non-Hodgkin's lymphomas studied, 55 (61%) stained positively for p53 protein. The proportion of positive cases increased from low grade non-Hodgkin's lymphoma and was higher in tumours of T cell origin. The percentage of positive cells (labelling index or LI) was significantly lower in low grade non-Hodgkin's lymphoma, but no difference was established between intermediate and high grade non-Hodgkin's lymphoma. In a large proportion of low grade non-Hodgkin's lymphoma the LI was below 1%. c-myc p62 immunoreactivity was identified in all cases. A significant positive correlation was established between p53 LI and c-myc p62 LI (rs = 0.453) as well as between p53 LI and PCNA LI (rs = 0.338).

CONCLUSIONS

p53 immunoreactivity was present in about half the cases of non-Hodgkin's lymphoma and was related to the grade of malignancy and possibly to the B or T cell origin of the tumour. It was also associated with the proliferation state as expressed by PCNA LI and c-myc p62 expression, indicating that the expression of these three cell cycle-related genes might be interrelated.

Analysis of rearranged immunoglobulin genes indicating a process of clonal evolution in chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is known to be a stable monoclonal neoplasm. In contrast to early studies demonstrating no more than two hybridizing immunoglobulin heavy chain bands corresponding to the two expected alleles, we have demonstrated an unexpected multiband pattern when the HindIII-digested DNA samples from 38 CLL patients were analysed by Southern blot hybridization using JH and C mu gene probes. In order to characterize the genetic basis for the multiband pattern, we molecularly cloned the immunoglobulin heavy chain genes of one of the patients whose leukaemic DNA sample demonstrated three hybridizing JH bands and a loss of the germline band. The cloned rearranged immunoglobulin genes could be divided, based on the restriction mapping and the hybridization with the various probes, into two basic patterns representing two alleles. In one of the cloned rearranged immunoglobulin genes a secondary rearrangement occurred that resulted in the addition of 300 base-pair long sequence into the switch region, and the creation of a HindIII restriction site. The results of the study suggest that clonal evolution occurs in some CLL, and that many of these neoplasms are indeed oligoclonal due to the accumulation of secondary genetic changes.

A comparative assessment of proliferating cell nuclear antigen, c-myc p62, and nucleolar organizer region staining in non-Hodgkin's lymphomas: a histochemical and immunohistochemical study of 200 cases

Proliferating cell nuclear antigen (PCNA) and c-myc p62 oncoprotein are two nuclear proteins expressed in proliferating and transformed cells. They can be recognized immunohistochemically in paraffin sections by the monoclonal antibodies PC-10 and c-myc 1-9E10, respectively. On the other hand, nucleolar organizer regions (NORs) are loops of DNA that carry the r-RNA genes and can be visualized in paraffin sections as black dots (AgNORs) using a silver impregnation method. It has been suggested that the mean number of AgNORs may reflect the cellular kinetics of a tumor. We independently examined 200 cases of non-Hodgkin's lymphomas using the monoclonal antibodies PC-10 and c-myc 1-9E10, as well as the AgNOR method. Our study shows a very significant correlation between PCNA, c-myc expression, and AgNOR count on the one hand and histologic grade on the other (P < .001), although a significant overlap among the three grades exists. PC-10, c-myc 1-9E10, and AgNOR scores are all shown to be linearly related, even though significant discrepancies were observed, and the correlation is stronger between PCNA and AgNORs (PCNA v c-myc p62, r = .551; PCNA v AgNORs, r = .746; c-myc p62 v AgNORs, r = .529; P < .001). A remarkable finding is that the intermediate group of lymphomas is heterogeneous as far as the proliferative rate is concerned: diffuse large cell cleaved/non-cleaved lymphomas (category G of the Working Formulation) are characterized by a significantly higher proliferative index, as evidenced by the elevated PCNA, c-myc p62, and AgNOR scores, in comparison with the other types of intermediate-grade lymphomas (P < .001). However, the proliferative rate is lower than that of the high-grade lymphomas (PCNA, P < .05; c-myc p62, P < .001; AgNORs, P < .005). No significant difference exists between B-cell and T-cell lymphomas except for the higher expression of c-myc p62 in intermediate-grade B-cell lymphomas, obviously due to the higher proliferative rate of diffuse large cell lymphomas. Based on our findings, it appears that the combination of PCNA, c-myc p62, and AgNORs provides an accurate estimate of the proliferative rate of non-Hodgkin's lymphomas in paraffin sections. Clinical studies may show whether this information has prognostic value independent of histologic classification. In addition, our results suggest that category G (diffuse large cell) lymphomas may belong to a malignancy grade higher than the intermediate grade, a suggestion consistent with their more aggressive biologic behavior.

The pathogenesis of AIDS lymphomas: a foundation for addressing the challenges of therapy and prevention

The association between AIDS and a spectrum of malignancies relates to chronic, profound defects in both cellular and humoral mechanisms of immune surveillance. Ironically, as AIDS patients live longer in response to increasingly effective antiretroviral therapies, the incidence of AIDS-related malignancies will continue to rise. The emergence of non-Hodgkin's lymphomas (NHL) as a major sequela of HIV infection bears a striking relationship to depletion of CD4 lymphocytes, particularly below 50/mm3. The ability to interfere early in the course of active HIV infection with additional mechanisms that may promulgate transformed cell hyperproliferation and clonal expansion--growth factors, HIV itself or other viruses (Epstein-Barr, in particular), aberrant oncogene or tumor suppressor genes expression, factors that induce genetic instability or DNA damage or alter host or viral genome repair--might decrease the occurrence or prolong the time to development of AIDS-related malignancies. The development of antiretroviral strategies that confer long-term suppression of HIV activity and relative preservation of immune function are essential to the ultimate prevention of malignancies that arise as a consequence of HIV-induced immunosuppression.

Non-Hodgkin's lymphomas in children. I. Patterns of disease and classification

Non-Hodgkin's lymphomas (NHL) are part of an overlapping spectrum of lympho-proliferative diseases in childhood. In the first of this 2 part series, the clinicopathological aspects of NHL in childhood are discussed. The rapid progression of disease, the high incidence of micrometastases (over 80%) at diagnosis, and the propensity of hematogenous spread to the bone marrow and the central nervous system (CNS) as well as the clinico-pathologic 'clusters' associated with particular presenting sites distinguish the pediatric forms of disease. Abdominal primary sites most frequently manifest diffuse undifferentiated (Burkitt's or non-Burkitt's) histopathology, B-cell immunophenotype, FAB-L3 cytomorphology and specific karyotypic and/or genotypic alterations of the immuno-globulin genes and the c-myc oncogene. Mediastinal presentation is associated with lymphoblastic histopathology, T-cell immunophenotype and a variety of less consistent karyotypic and genotypic aberrations. Ki-1 lymphoma, a rare subtype of large cell NHL with specific features is often of T cell origin. The requirements for diagnosis, staging and monitoring are presented in the context of the associations between clinico-pathological presentation and subsequent behavior. The most frequent sites of disease progression and relapse are involvement of the bone marrow and the CNS. For Burkitt's lymphoma there is a historic perspective and a description of particular epidemiologic, clinical, virologic, immunophenotypic and genotypic features. Cytogenetic and molecular biologic studies of genomic rearrangements are advancing the understanding of oncogenesis, clonality, lineage, and clinical behavior. The capacity to detect and amplify DNA from submicroscopic disease may contribute to prognostic stratification both at diagnosis and during subsequent monitoring.

Non-Hodgkin's lymphomas in children. II. Treatment

The prognosis of non-Hodgkin's lymphoma (NHL) in childhood has improved steadily in the last 2 decades. This is primarily the result of increasingly effective chemotherapy regimens tailored to defined and relatively homogeneous prognostic categories and tested in prospective clinical trials. Surgical excision remains of prognostic benefit only when near-total resection can be performed without delay of chemotherapy. The role of radiation therapy is now limited to the treatment of overt central nervous system (CNS) lymphoma, disease unresponsive to chemotherapy, and certain emergencies. Effective 'prophylactic' treatment of the CNS has been achieved in most series by intrathecal and systemic chemotherapy alone. The most relevant modality of treatment is chemotherapy and a very large number of protocols have been published. The origins of current multi-agent regimens stem both from early experience with cyclophosphamide in endemic Burkitt's lymphoma and from therapeutic studies of acute lymphoblastic leukaemia. Sub-stratification of non-localized NHL has produced protocols designed for either lymphoblastic (mostly T cell) or non-lymphoblastic (mostly B cell) categories. While the cure rate for lymphoblastic lymphoma now exceed 70%, the non-localized non-lymphoblastic disease remains a major obstacle to cure. These patients frequently present with large abdominal primaries and are prone to regional as well as hematogenous dissemination. In particular, involvement of the CNS is now considered to be the most adverse prognostic variable in this group. Recently, highly intensive regimens are addressing these obstacles. On the other hand, NHL defined as localized has been shown to be curable in up to 95% of children with the use of simple chemotherapy regimens as short as 6 months in duration. Salvage of patients who relapse during or after chemotherapy remains bleak but cures are possible with regimens incorporating bone marrow transplantation from either an autologous or allogeneic source. Experimental methods, including biologic and immune response modifiers may also offer future promise.

Evaluation of residual disease in B-cell chronic lymphocytic leukemia patients in clinical and bone-marrow remission using CD5-CD19 markers and PCR study of gene rearrangements

We evaluated minimal residual disease (MRD) in 23 CD5 + B-chronic lymphocytic leukemia (CLL) patients who achieved clinico-hematological remission confirmed by bone-marrow biopsy. MRD was evaluated by dual marker analysis flow-cytometry using CD5 and CD19 markers, and by the study of Ig heavy chain gene rearrangements using the fast polymerase chain reaction (PCR). According to our laboratory conditions patients were considered to be in complete phenotypic remission when total CD19+ cells were < 25% and the ratio of CD5 + CD19 + /CD19 + cells was < 25%. According to these strict criteria only 9 of the 23 patients were in complete phenotypic remission. In order to evaluate the sensitivity of the above method, PCR analysis of the configuration of the Ig heavy chain gene region was performed in 12 of these patients. Five of 7 patients in complete phenotypic remission retained a detectable monoclonal rearrangement of the Ig heavy chain gene. For the remaining 5 patients in partial phenotypic remission, only one failed to show a monoclonal band and this is probably explained by the presence of an unusual gene rearrangement. In conclusion, this study suggests that PCR is more sensitive than dual marker flow-cytometry for evaluation of residual disease and that it is indeed possible to achieve complete remission at the molecular level, in B-CLL. Nevertheless, we suggest a word of caution as this was a retrospective study, and samples were not assessed before treatment. Thus the possibility that apparent molecular remission might correspond to unusual gene rearrangements cannot be completely excluded in these cases.

EBV genome and immunoglobulin gene rearrangement in the differential diagnosis of nasopharyngeal carcinoma and lymphoma

Head and neck tumors include nasopharyngeal carcinoma (NPC) and lymphoma. The differential diagnosis of these tumors is based on histology, immunocytochemical staining, and EBV serology. In rare cases it might be difficult to distinguish between NPC and lymphoma in HE section or biopsies. DNA hybridization with cloned EBV and human immunoglobulin gene fragments allows the detection of EBV-related sequences and immunoglobulin gene rearrangements. The presence of EBV genome supports the diagnosis of NPC or EBV related BL, while rearrangement of immunoglobulin genes points to B-cell lymphoma. The diagnosis in 11 patients suspected of head and neck tumors was carried out by hybridization of DNA extracted from the tumors and assayed with cloned EBV and IgHCJ DNA probes. One patient proved to have EBV-associated BL based on positive hybridization with EBV probes and immunoglobulin rearrangement, presenting a unique hybridization with cloned EBV DNA BamHI W fragment, with bands of 3.2 and 3.9 kb. BL was confirmed in this patient by demonstration of c-myc rearrangement. A second patient was negative in hybridization with EBV, and positive for immunoglobulin rearrangement, and therefore was diagnosed as having B-cell lymphoma. In seven patients NPC was confirmed by hybridization with EBV-DNA probes. In two patients, both NPC and B-cell lymphomas were excluded.

Immunogenetic analysis of bone marrow aspirates in patients with non-Hodgkin lymphomas

The immunogenetic analysis (IGA) on the staging bone marrow aspirates in 15 patients with non-Hodgkin lymphoma (NHL) is reported. We found the sensitivity of IGA and morphologic examination in detecting bone marrow involvement by malignant lymphoma to be 91% and 82%, respectively. In 11 cases there was agreement between the morphologic findings and IGA. In 8 of these 11 cases, IGA confirmed the morphologic involvement of the bone marrow by demonstrating clonal rearrangement of either the immunoglobulin heavy- and/or light-chain or the T-cell receptor beta chain (TCR) genes. In 3 of these 11 cases, morphology showed no involvement and IGA showed germline configurations for both the immunoglobulin heavy- and light-chain or the TCR genes. In 2 additional cases the techniques proved to be complementary, as involvement was detected by only 1 of the 2 procedures. In 1 of these 2 cases, IGA showed gene rearrangement while morphologic examination was negative for involvement by NHL, while in the other case, morphologic examination showed involvement by NHL, but IGA did not show gene rearrangement. IGA was also useful in determining the clonality of solitary lymphoid nodules in the 2 remaining cases when morphologic interpretation was equivocal. In the 12 cases with bone marrow involvement, the immunophenotype and immunogenotype agreed in 11 cases. In the one case in which there was a discordance between the immunophenotype and immunogenotype, the immunophenotype was incorrectly interpreted as B-cell lineage, while the immunogenotype demonstrated a T-cell lineage. IGA also demonstrated a clonal population in 1 case of T-chronic lymphocytic leukemia where other techniques could not demonstrate the clonality of the pathologic process. IGA analysis may detect bone marrow involvement in NHL which may not be detected by morphologic examination because of patchy distribution.

Immunoglobulin heavy chain gene rearrangements in chronic lymphocytic leukaemia: correlation with clinical stage

A search for a correlation between the clinical stage of chronic lymphocytic leukaemia (CLL) and the pattern of immunoglobulin heavy chain gene rearrangements was undertaken. DNA samples from the leukaemic cells of 38 CLL patients were analysed by Southern blot hybridization. Using probes for the immunoglobulin heavy chain J (JH) and C mu regions a marked heterogeneity of the hybridization patterns was observed in both regions. The number of JH hybridization bands varied from one to four and more than two were found in 58% of the patients. In 42% of the patients no germline JH genes were found. One to three additional C mu bands were observed in 34%, but the germline was preserved in all samples. There was no correlation between the clinical stage and the number of hybridizing JH bands; however, a significant correlation was found between the loss of JH germline band or a C mu multiband pattern and advanced stage of the disease. The genetic events in the immunoglobulin genes observed in advanced CLL patients are assumed to result from clonal evolution and tumour progression.

Immunologic and molecular evaluation of residual disease in B-cell chronic lymphocytic leukemia patients in clinical remission phase

This study evaluates residual disease in 28 B-cell chronic lymphocytic leukemia (B-CLL) patients who obtained a clinicohematologic remission after intensive chemotherapy. Sixteen of 28 patients (57%) showed a normal number of circulating B-lymphocytes, as demonstrated by the low percentage of mouse rosette-forming cells (M-RFC), surface immunoglobulins (SIg), and CD24-positive cells. Clinically, a lower number of relapses occurred in this group of patients compared to those with a persistent expansion of peripheral B-cells (P less than 0.05). In order to assess monoclonality of the residual peripheral B-cell population, the distribution of SIg light chains was investigated on the B-cell-enriched fraction of 15 of these 16 cases. Only six of them had a kappa/lambda ratio which ranged between 1.7:1 and 3:1, whereas the remaining patients still displayed a clearly imbalanced kappa/lambda Ig light chain distribution. On the other hand, the analysis of the configuration of the Ig heavy chain gene region, performed in nine cases (including five of the above six cases), showed the persistence of a rearranged pattern in all cases tested but one. Therefore, residual monoclonal B-cells were found also in the majority of cases which displayed the lowest kappa/lambda ratio, a normal bone marrow lymphocytosis and a long-lasting clinical remission. Studies at the DNA level confirm that a remission is rarely achieved in this disease in spite of intensive and prolonged chemotherapy. Nonetheless, the follow-up of B-CLL patients by conventional immunologic markers may be helpful to better define response to therapy and to predict the occurrence of clinical relapse.

Gamma heavy chain disease associated with Hodgkin's disease. Clinical, pathologic, and immunologic features of one case

This report describes the clinical, pathologic, and immunologic features of a patient with gamma heavy chain disease (gamma-HCD) associated with Hodgkin's disease (HD). The diagnosis of gamma-HCD was established by serum electrophoresis and immunoelectrophoresis and confirmed by biochemical analysis of patient's serum showing the presence of an incomplete gamma chain, with an approximate molecular weight of 40 kilodaltons. The diagnosis of HD rested upon the presence of systemic lymphadenopathy, the typical histologic pattern and reactivity of Reed-Sternberg cells with the LeuM1-CD15 monoclonal antibody. The two diseases developed independently, in the absence of any immunosuppressive treatment. Furthermore, there was some evidence suggesting that HD tissue was not responsible for the production of the incomplete gamma chain. This and similar cases may provide a model for a better understanding of the events leading to the simultaneous outgrowth of two lymphoid neoplasias in the same patient.

Laboratory and clinical applications of monoclonal antibodies for leukemias and non-Hodgkin's lymphomas

Important insights into leukocyte differentiation and the cellular origins of leukemia and lymphoma have been gained through the use of monoclonal antibodies that define cell surface antigens and molecular probes that identify immunoglobulin and T-cell receptor genes. Results of these studies have been combined with markers such as surface membrane and cytoplasmic immunoglobulin on B lymphocytes, sheep erythrocyte receptors on T lymphocytes, and cytochemical stains. After using all of the aforementioned markers, it is now clear that acute lymphoblastic leukemia (ALL) is heterogeneous. Furthermore, monoclonal antibodies that identify B cells, such as the anti-CD20 and anti-CD19 antibodies in combination with studies of immunoglobulin gene rearrangement, have demonstrated that virtually all cases of non-T-ALL are malignancies of B-cell origin. At least six distinct subgroups of non-T-ALL can now be identified. T-ALL is subdivided by the anti-CD7, anti-CD5, and antibodies that separate T lymphocytes subsets into three primary subgroups. Monoclonal antibodies are also useful in the subclassification of non-Hodgkin's lymphoma, and certain distinct markers can be correlated with morphological classification. Although monoclonal antibodies are useful in distinguishing acute myeloid from acute lymphoid leukemias, they have less certain utility in the subclassification of acute myelogenous leukemia (AML). Attempts to subclassify AML by differentiation-associated antigens rather than by the French-American-British (FAB) classification are underway in order to document the potential prognostic utility of surface markers. Therapeutic trials using monoclonal antibodies in leukemia and lymphoma have been reported. Intravenous infusion of unlabeled antibodies is the most widely used method; transient responses have been demonstrated. Antibodies conjugated to radionuclides have been quite successful in localizing tumors of less than 1 cm in some studies. Therapy trials with antibodies conjugated to isotopes, toxins, and drugs have shown promise. Purging of autologous bone marrow with monoclonal antibodies and complement in vitro has been used in ALL and non-Hodgkin's lymphoma; preliminary data suggest that this approach may be an effective therapy and may circumvent many of the obstacles and toxicities associated with in vivo monoclonal antibody infusion.

Comparison of phenotyping and genotyping of lymphoid neoplasms

Comparison of phenotyping (PT) and genotyping (GT) of lymphoid neoplasms was performed on 51 specimens including lymph nodes, bone marrows, and body fluids. PT was performed with a flow cytometer using a large monoclonal antibody panel. GT included the testing for gene rearrangements of heavy chain, kappa and lambda light chains, and T-cell receptor beta-chain genes with DNA probes. The results obtained from these two techniques were generally compatible in terms of clonality and cell lineage. Only one case of B-cell lymphoma was not diagnosed by PT but showed gene rearrangement. For T-cell lymphoma, GT offers a more definitive diagnosis than does PT. Biclonality was demonstrated in one case of hairy cell leukemia by GT only. The rearranged band also offers a definitive clonal identification based on electrophoretic mobility. GT can detect a monoclonal population as small as 5% and can be performed on old or fresh specimens. PT requires 20% abnormal cells and a fresh specimen. It is concluded that GT is superior to PT for lymphoid tumor diagnosis, but it should be reserved as a supplementary test at this stage because of its technical complexity.

Immunoglobulin and T cell receptor gene rearrangements and in situ immunophenotyping in lymphoproliferative disorders

We investigated for rearrangements of the immunoglobulin (Ig) heavy and light chain genes and of the T cell receptor gamma (TCR gamma) and beta (TCR beta) genes 45 biopsy samples from a variety of lymphoproliferative disorders. They were diagnosed histopathologically and immunophenotypically as non-Hodgkin's lymphomas (NHLs) of the B cell type (19 cases), NHLs of the T cell type (3 cases), NHLs of "undetermined" cell type (3 cases), atypical lymphoid proliferation (1 case) and AIDS-related lymphadenopathies with florid polyclonal follicular hyperplasia (19 cases). A monoclonal proliferation of B cells was shown by DNA analysis in all 19 B cell NHLs. In two immunohistologically determined T cell NHLs (both diagnosed as mycosis fungoides) the cells had rearrangements of TCR beta gene, whereas in the third case (lymphoblastic NHL) the cells had rearrangements of Ig heavy chain and TCR gamma and TCR beta genes. None of the B cell NHLs exhibited TCR gamma and TCR beta gene rearrangement bands. All the "undetermined" cell NHLs demonstrated rearrangements of Ig heavy chain gene associated with the germ line TCR gamma and TCR beta genes; in two cases light chain gene rearrangements were also found. The atypical lymphoid proliferation, in which the differential diagnosis was between a reactive or malignant process, and two out of 19 cases of florid polyclonal follicular hyperplasia showed a clonal B cell population by DNA analysis. This study indicates that there was a strong correlation between the rearrangements of specific genes and the immunophenotype of the NHL; moreover, DNA analysis of tissue biopsy specimens from phenotypically "undetermined" cell NHLs and from equivocal lymphoid proliferation using Ig and TCR gene probes yielded an answer in the cases analyzed. The significance of clonal B cell expansions found in two AIDS-related lymphadenopathies should be interpreted with caution.

Restriction of blood and marrow CLL-B cells to free L-chain Ig secretion: implication for normal B-cell function and control

The culture supernatant immunoglobulin (CSIg) of blood mononuclear cells (MNCs) from 14 patients with chronic lymphocytic leukemia (CLL) was determined using a panel of nanogram-sensitive radioimmunoassays that measured IgM, IgG, IgA, total kappa-Ig, and total lambda-Ig. Bone marrow cells from three patients were also cultured and the blood and marrow CSIg results were compared. The CSIg of 1-day cultures was employed as a measure of shed surface membrane Ig (SmIg) for the 7- and 14-day cultures. Adjusting for shed SmIg, it was found that in resting unstimulated conditions, monotypic free light (L) chain was virtually the only identifiable secreted Ig product in 12 of 14 blood MNC cultures and in three of three marrow cell cultures. In pokeweed mitogen (PWM)-stimulated cultures, monotypic free L chain also dominated, except for significant polyclonal Ig secretion found in three cultures from residual normal blood MNCs. The secretion by CLL-B cells of significant amounts of free L chain with a virtual absence of whole Ig raises important questions about the presence and function of phenotypically equivalent normal B cells in blood and bone marrow, and also the immunological role of secreted free L chain. Noting recent evidence that PWM-stimulated normal blood MNCs secrete significant amounts of polyclonal free L chain, the argument is advanced that normal blood and bone marrow contain B cells of CLL-B phenotype and that secreted free L-chain-bearing clonal idiotypic markers interact with autologous cells of the idiotypic regulatory network and possess a key role in the regulation of clonal growth and Ig synthesis.

Role of immunotyping in chronic lymphocytosis: review of the natural history of the condition in 145 adult patients

We investigated the clinical value of immunotyping in 145 consecutive adult patients with absolute or relative lymphocytosis: 132 (91%) had B-cell lymphocytosis, 5 (4%) had T-cell lymphocytosis, 2 (1%) had hairy cell leukemia, and 6 (4%) had reactive lymphocytosis. Of the five patients with T-cell lymphocytosis, four were best categorized as having T gamma-chronic lymphoproliferative disease and had an indolent clinical course. Of the 132 patients with B-cell lymphocytosis, 121 (92%) had B-cell chronic lymphocytic leukemia (B-CLL), and 11 (8%) had small cleaved ("lymphosarcoma") cell leukemia. Patients with small cleaved cell leukemia had a worse clinical outcome than did those with B-CLL. We further analyzed the surface immunoglobulin (sIg) and CD20 (B-1) antigen expression patterns in B-CLL to determine whether any correlation existed with clinical outcome. A subset of patients with B-CLL in whom sIg was expressed in less than 20% of their lymphocytes had the best clinical outcome. HLA-DR (Ia-like) antigen typing helped identify B-CLL cases with minimal or no sIg expression. CD20 (B-1) antigen was weak or undetectable in most cases of B-CLL. Patients with B-CLL who had CD20 (B-1) in more than 20% of their lymphocytes did not have a different prognosis. Our data provide the incidence and natural history of the various subsets of CLL in a series of patients at a single institution. The type and extent of immunotyping necessary and practical in the clinical management of patients with CLL are explored.

Plasma cell leukaemia of non-producer type with missing light chain gene rearrangement

A case of plasma cell leukaemia of non-producer type is described. The patient presented with typical clinical features of plasma cell myeloma, including multiple osteolytic lesions, hypercalcaemia, renal failure and reduced polyclonal immunoglobulins, except that M-component was not detected in either the serum or urine. Morphological examinations showed a plasmacytoid appearance of the neoplastic cells, while immunological studies failed to detect cytoplasmic immunoglobulin or secretory capacity. The surface phenotype of CD38+, PCA-1+, DR-, CD20-, CD24-, CD9-, CD10- and surface immunoglobulin- was compatible with mature plasma cells. Chromosomal analysis showed the 14q+ marker due to translocation (6;14) and deletion of the short arm of chromosome 1. Analysis of immunoglobulin genes revealed the presence of heavy chain gene rearrangement, but the light chain genes, both kappa and lambda, remained in germline configuration. Such defective immunoglobulin gene rearrangement may be responsible for the failure of immunoglobulin biosynthesis and secretion by the neoplastic plasma cells. Furthermore, it is suggested that the morphological and phenotypic development of B cells may not necessarily depend on immunoglobulin light chain gene rearrangement, and that the oncogenic event in myeloma may occur at an earlier stage of B cell differentiation.

Evaluation of immunity

Immunodeficiency disease is rapidly increasing in frequency. The AIDS epidemic, the increasing use of transplantation with immunosuppression, the aggressive immunotherapy, the persistent deficiencies after bone marrow transplantation--all contribute to the astronomically increasing numbers of patients with host defense failure. This review has presented my viewpoint as to the approaches which can be utilized by practitioners with varying focal points to provide diagnosis and maximize the potential for a cure today or at least to provide the beginnings of understanding from which will come the cures of tomorrow.

Genotypic monoclonality in immunophenotypically polyclonal orbital lymphoid tumors. A model of tumor progression in the lymphoid system. The 1986 Wendell Hughes lecture

Molecular genetic (genotypic) analysis elucidates gene rearrangements within lymphocytes that are responsible for either immunoglobulin production in B-lymphocytes or the expression of cell-surface antigen recognition receptors in T-lymphocytes. Molecular genetic analysis is far more sensitive than immunophenotypic methods for the detection of small clones of lymphocytes because as few as 2 to 5% of cells in an infiltrate can be discovered to possess the same rearranged DNA sequences with genetic probes. In truly polyclonal proliferations, each lymphocyte reorganizes its immunoglobulin or T-antigen receptor genes in a unique manner, resulting in an almost infinite number of combinations of genetic rearrangement and the absence of any new hybridizing bands upon Southern blotting. In monoclonal proliferations, a new, homogeneous, nongermline band is identified on Southern blotting because a sufficiently large number of lymphocytes exhibit an identical genetic rearrangement. In a group of five orbital lymphoid tumors that appeared to be benign reactive hyperplasias by light microscopy and that were polyclonal by immunophenotypic methods, three were found by molecular genetic analysis to harbor small clones of B-lymphocytes with new rearrangement bands on Southern blotting. No clonal abnormalities of T-lymphocytes were found in these five lesions, despite the fact that they were the preponderant cells in the tumors. These observations suggest that "reactive lymphoid hyperplasia" of the orbit may be an unstable lesion, owing to a T-cell immunoregulatory imbalance, with the potential for developing clonal expansions of B-lymphocytes that nonetheless usually remain localized to the orbit.

Simultaneously increased expression of the c-myc and mu chain genes in the acute blastic transformation of a chronic lymphocytic leukaemia

A B-cell chronic lymphocytic leukaemia terminated, 5 years from the onset, with a blast crisis. Karyotype analysis showed that the terminal lymphoblastic population evolved from the original B lymphocytic clone. The levels of expression of several oncogenes, as well as the mu chain gene, were assayed by Northern blot hybridization analysis of RNA extracted from the lymphoid populations before and after the 'acute transformation'. A seven- to eight-fold increase in the expression of c-myc and mu chain genes was observed in the blast population. c-myb, c-fes, c-Haras were not expressed either before or after the blastic transformation.

The arrangement of immunoglobulin and T cell receptor genes in human lymphoproliferative disorders

Immunoglobulin and T cell antigen receptor genes in their germ-line form are organized as discontinuous DNA elements that are joined by recombinations during lymphocyte development. The analysis of immunoglobulin gene structure and arrangement has been of great value in the study of human lymphoid neoplasms. The analysis of rearranged immunoglobulin and T cell receptor genes has been of value in defining the lineage (T or B cell) of neoplasms that were of controversial origin previously, determining the clonality of abnormal lymphocyte proliferations, diagnosing and monitoring the therapy of lymphoid malignancies, determining the state of maturation and the causes for failure of maturation of cells of the B cell series, and providing major insights into the cause of malignant transformation of B and T lymphoid cells. Thus, the application of this molecular genetic approach has great potential for complementing conventional marker analysis, cytogenetics, and histopathology, thus broadening the scientific basis for the classification, diagnosis, and monitoring of the therapy of lymphoid neoplasia.

Multiple chromosome abnormalities in a drug resistant TdT positive B-cell leukemia

A 17-year old caucasian male presented with B-cell acute leukemia which proved aggressive and refractory to treatment. Cytogenic investigation showed a single clone with a complex karyotype 49,XY,del(2)(p13),+4,del(4)(p11),-6,+i(6)(p),+7,+8, t(8;14), (q24;q32),del(17)(p11). This includes the Burkitt's translocation and a deletion at the site of the immunoglobulin kappa light chain gene. Clonal evolution included tetraploidy, duplication of the derived chromosomes and, terminally, trisomy 1q. Immunological investigation revealed a monoclonal population of B-cell blasts, expressing the kappa light chain, and with an extremely rare combination of SIg and TdT positivity. Immunoglobulin gene rearrangement confirmed monoclonalility. Tetraploidy of the clone and del(17)(p11) have been previously described only in a cell line or at end stage disease in B-ALL. It is suggested that the chromosomal abnormalities present at diagnosis were directly related to the refractory nature of this leukemia.

Differentiation-linked leukemogenesis in lymphocytes

Most human lymphoid malignancies preserve a pattern of gene expression reflecting their proliferative activity and the development level of clonal expansion and maturation arrest. Characteristics of leukemia and other cancer cells frequently considered to reflect aberrant differentiation may more often reflect clonal selection of cell types that are normally infrequent and transitory. The differentiation status of progenitor or mature lymphoid cells influences which genetic elements are at risk of being exploited, via mutation, recombination, or deletion, for clonal advantage. These alterations may frequently arise spontaneously as a consequence of the unique developmental and functional programs of lymphoid cells and have as a major phenotypic consequence the stabilization of transitory cellular phenotypes.

Idiotype variant cell populations in patients with B cell lymphoma

Using isolated idiotype (Id) protein we generated panels of antibodies in two patients with follicular lymphoma, one of whom had never received prior chemo-or radiotherapy. Flow cytometry and frozen section tissue staining of tumor with these monoclonal antibodies (mAb) revealed multiple subpopulations within each tumor. Individual mAb stained between 7% and 83% of surface Ig+ cells in the tumor samples. These subpopulations were overlapping and no single antibody recognized all the tumor cells. However, combinations of antibodies seemed to capture total tumor in both cases. In some instances, the percentage of tumor stained by a single mAb varied over time, and differed between lymph nodes sampled at the same time. Because a single species of Id protein was used to generate mAb in each case, it appears that the antibodies were directed against idiotopes variably shared by different populations within each tumor, and this was confirmed by crossblocking studies. Tumor cells from one patient were fused to a nonsecreting heteromyeloma line K6H6/B5, and most of the resulting hybrids secreted Id protein. Four mAb were used to screen the Id proteins secreted by these hybrids, and 11 different variants (16 maximal) were found. Southern blot analysis of rearranged Ig genes was done in two hybrids and biopsy material. Identically rearranged light-chain genes were seen but it appeared as though extensive somatic variation had occurred in heavy chain genes. These studies indicate that: striking Id variation can exist at diagnosis in untreated patients, the percentage of tumor represented by an individual variant may change with time and may differ between tumor sampled from different anatomical locations, and somatic variation appears to be responsible for the observed heterogeneity. Although this degree of variation makes anti-Id antibody therapy more difficult, appropriate combinations of mAb should be more efficacious than single antibodies in such cases.

Evidence by radioimmunoassay that mitogen-activated human blood mononuclear cells secrete significant amounts of light chain Ig unassociated with heavy chain

The culture supernatant (CS) Ig of PWM-activated human blood mononuclear cells was quantitatively determined using a panel of nanogram-sensitive radioimmunoassays (RIAs) that separately measured IgG, IgM, IgA, total kappa Ig, and total lambda Ig. After initial RIA quantitation, separate CS aliquots were exposed to either a polyisotypic anti-heavy (H) chain or a nonimmune IgG solid-phase immunoabsorbent, and then reassayed for Ig content. The reassay results revealed that the anti-H chain-absorbed CS aliquots retained significant amounts of kappa and lambda Ig, but yet had a virtual absence of isotypic IgG, IgM, and IgA. Comparisons of the absorbed CS aliquots suggested that as much as one-fourth to one-third of the total secreted L chain Ig in PWM-activated cultures lacked RIA-detectable associated H chain. This unexpected finding of significant amounts of unbound L chain in mitogen-stimulated cultures raises important theoretical issues relative to the functional role of secreted free L chain and the prospects that free L chain levels may represent useful quantitative markers of B-cell stimulation.

Mouse x human heterohybridomas as fusion partners with human B cell tumors

Surface idiotype (Id) of B cell malignancies is an excellent tumor-specific marker. We have, however, recently described heterogeneity of tumor Id in some cases. We therefore sought a way to isolate, reliably and efficiently, different species of idiotype from a potentially heterogeneous population. In this report we demonstrate our success using a series of mouse X human heterohybridomas as fusion partners with human B cell tumors. Three lines (K6H6/B5, K6H9/G12, SBC/H20) demonstrated excellent fusion efficiency with 75%-85% of wells plated containing hybrids. Two cell lines, K6H9/G12 and SBC/H20 had a tendency to secrete a single Ig chain (heavy or light chain), whereas the K6H6/B5 cell line secreted whole immunoglobulin (Ig) in greater than 80% of the hybrids. This line secreted significant amounts of Ig (2.73 micrograms/ml/10(6) cells) and was relatively stable in culture. Since this line has such a high fusion efficiency the products of normal B cells admixed with tumor may be recovered, allowing the opportunity of isolating host anti-tumor antibodies. In order to prove that hybrids were derived from the tumor, Southern blot analysis of rearranged DNA was performed in selected cases. Fusions with this line provide the potential for recovering many different species of idiotype in a mixed population. This will facilitate the production of mouse monoclonal anti-idiotype antibodies against many variants and against different idiotopes.