Molecular aspects of immunoglobulin expression by human B cell leukemias and lymphomas

Measurement of free kappa and lambda chains in serum and the significance of their ratio in patients with multiple myeloma

An inhibition enzyme-linked immunoassay technique using commercially available antibodies has been developed for the quantitation of both kappa and lambda light chains in the serum of patients with B-cell malignancies. Assay conditions were selected to enable measurement of free light chains in the concentration range between 0.1 and 20 mg/l. The normal range for free lambda chains in serum was found to be 0.4-4.2 mg/l and for free kappa chains it was 1.6-15.2 mg/l. At diagnosis the serum of most patients with multiple myeloma contained increased levels of the malignant free light chain and in some cases there was also elevation of the non-malignant light chain. The absolute level of the malignant light chain at diagnosis did not correlate with survival nor with laboratory parameters such as IgM or creatinine. A correlation with beta 2 M and serum paraprotein levels was evident only in cases of IgA myeloma. Although the absolute level of free serum light chain had no value as a prognostic indicator, the ratio of kappa:lambda chains closely followed the clinical assessment of disease status, being near the normal range (1.2-9.1) in plateau phase or stable disease. During periods of progressive disease this ratio ranged from 19 to 460 (n = 14) in patients with kappa myeloma, and 0.0013-0.14 (n = 9) in patients with lambda myeloma. Determination of the ratio of free light chains in the serum may allow effective monitoring and earlier warning of disease progression in patients with multiple myeloma.

Regulation of IL-4 responsiveness in lymphoma B cells

The responsiveness to IL-4 with and without costimulation with anti-IgM antibodies or phorbolester was studied in 35 cases of low grade non-Hodgkin lymphoma by analyzing enhancement of CD23 and HLA class II expression. The predominant phenotype responds directly to IL-4. Separate differentiation states can be distinguished according to coordinate or differential upregulation of CD23 and HLA class II molecules by IL-4 alone, and differences in responsiveness to anti-IgM antibodies. A particular subgroup of B-lymphoma cells defines a separate stage of B-cell differentiation. They fail to express high affinity binding sites for IL-4 and accordingly do not respond to IL-4-mediated signals. Cross-linking membrane IgM receptors or direct activation of protein kinase C via phorbolester induces IL-4 receptor expression and subsequent IL-4 reactivity.

Immuno-phenotype and proliferative response of B-cell chronic lymphocytic leukemia

This study examines the immunophenotypic profiles in both pretreated and treated CLL patients which could be useful from the prognosis point of view. Patients suffering from B CLL and having IgG markers were relatively more aggressive than cells bearing IgM phenotypes. Male predominance is observed in male/female ratio in this disease. B CLL showed heterogeneity by showing reactivity against various T cell markers such as CD5 (present on mature T cells) and also CD4 (T helper/inducer), CD8 (T suppressor/cytotoxic) and a very high percentage of Ia (HLA-DR). The proliferative response to cells to stimulation with PHA and PWM indicated that there is a primary defect in the capacity of these small lymphocytes to undergo a proliferative response due to an intrinsic defect in the B lymphocytes. This study also reflects a maturation arrest in the later developmental stage of B lymphopoiesis. The three findings which are novel are the difference in prognosis between IgG-IgM and IgG, the changes in T cell subsets and the mitogenic response.

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.

Multiple myeloma: relationship between light chain isotype suppression, labelling index of plasma cells, and CD38 expression on peripheral blood lymphocytes

In this study we have investigated the relationship between the labelling index of plasma cells, the expression of CD38 positive lymphocytes in the peripheral blood, and light chain isotype suppression. This study confirms the relationship between plateau-phase disease and light chain isotype suppression (LCIS) and documents an inverse relationship between LCIS and CD38 positive lymphocytes (.001 less than P less than .01), which is similar to the relationship we have described with the expression of CD10 positive lymphocytes. PCA-1 is rarely expressed in the peripheral blood of patients with myeloma and does not fulfill a role as a marker of active vs. stable disease. There is no relationship between the labelling index of plasma cells and LCIS, because many patients can enter a stage of progressive disease and yet have a labelling index of less than 1% at that time, although a labelling index less than 1% is present in the majority of patients with LCIS. beta-2-microglobulin (beta 2M) also fails to differentiate these two phases of disease in myeloma and does not have a relationship with LCIS, CD38 expression, or CD10 expression. These data suggest that myeloma, like chronic granulocytic leukemia (CGL), can be considered as having two phases of disease: a stable or chronic phase disease, as identified by the presence of LCIS, the absence of CD10 and CD38 positive lymphocytes in the peripheral blood, and a low labelling index, and progressive disease, which is associated with the loss of LCIS and of, CD10 and CD38 positive lymphocytes in the peripheral blood and a high labelling index, although in many cases of progressive disease, the labelling index may also be low. beta 2M does not differentiate between these states.

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.

Mitogenic stimulation of malignant B cells CLL: diminished in-vitro stimulation with anti-CR1 antibodies

Peripheral B lymphocytes of five CLL patients were tested in a radioimmunoassay to determine the density of the C3b receptor (CR1) and the cells were assayed for their ability to mature into IgM secreting cells after in-vitro culture with a combination of Pokeweed Mitogen (PWM) and antibodies directed against CR1. Despite the presence of normal amounts of CR1 on the leukemic B cells, crosslinking of these receptors by anti-CR1 antibodies stimulated only a fraction of the leukemic cell population to differentiate into IgM secreting cells. These results add to the partial functional impairment of CLL-B cells.

Heterogeneity in neoplastic cell populations in chronic lymphocytic leukaemia defined by immunoglobulin expression and secretion in vitro

Neoplastic cell populations were prepared from peripheral blood and bone marrow samples of four patients with typical B-cell chronic lymphocytic leukaemia (CLL). Lymph node biopsies were also performed and used as a source of neoplastic cells for two of these patients. Using sensitive ELISA systems to determine unstimulated immunoglobulin (Ig) secretion of these tissue-derived populations in culture, a discrepancy between the nature of the secreted Ig products was found. Peripheral blood and lymph node-derived populations from each patient secreted both whole molecules of Ig and a large molar excess of Ig light chains (free LC), whereas all bone marrow-derived population secreted only free LC. The isotypic expression of intrinsic, cell-surface immunoglobulin (sIg), determined using immunofluorescence microscopy and flow cytometry, was, however, indistinguishable between different tissue-derived populations for any one patient. The absolute amounts of LC secretion were not markedly different between the tissue-derived populations (blood = 5.3 +/- 1.7; marrow = 3.5 +/- 1.3; lymph node = 11.5 ng per 2 X 10(7) cells per h) and thus failure of detection could not account for this discrepancy. Furthermore, the presence of sIgM and sIgD on each tissue-derived population indicated that all were at least capable of synthesizing whole Ig for membrane insertion. These results suggest that the assessment of a B-cell function, Ig secretion, is a valuable technique for determining small differences within neoplastic populations from individual patients. These functional differences may be related to the maturity of different cells within clonal populations.

Ploidy, proliferative activity, cluster differentiation antigen expression and clinical remission in high-grade non-Hodgkin's lymphoma

Using a large range of monoclonal antibodies to specific cluster differentiation antigens the phenotypes of a series of high-grade non-Hodgkin's lymphomas of B- and T-cell type were investigated. Cell ploidy and proliferative fraction were assessed by fluorescent staining of DNA and flow cytometry and data on the incidence of complete clinical remission were obtained. With the exception of some lymphoblastic lymphomas, high-grade B-cell lymphomas normally expressed the pan B-cell antigens CD19 and CD22 but only immunoblastic lymphomas consistently expressed the pan B marker CD20. Variable, generally weak expression of CD21 was observed whilst CD23 expression was most prevalent in rapidly proliferative cases and in Burkitt's and centroblastic lymphomas. A rapidly proliferative, multilobated B-cell lymphoma displayed phenotypic properties intermediate between centroblastic and immunoblastic lymphomas. The T-cell lymphomas generally showed low proliferative activity and expression of CD4 prevailed over CD8. Most cases also showed CD2 and CD5 positivity with some also showing CD3 and CD7 expression. Patients with rapidly proliferative diploid or DNA aneuploid tumours obtained complete remission more readily than patients with lowly proliferative diploid tumours. An excess of early deaths occurred among T-cell cases.

The correlation between surface immunoglobulin expression and the leucocyte-common antigen in B-cell chronic lymphocytic leukaemia

The expression of the 230 kD glycoprotein of the leucocyte-common antigen by the leukaemic lymphocytes of patients with B-cell CLL, PLL and HCL and of normal B lymphocytes has been measured in a flow cytometer by the binding of the McAb F8-11-13 and surface tritiation. Its expression has been correlated with the expression of surface immunoglobulin heavy chain and light chain. The levels of binding of F8-11-13 and sIg cover a wide range within the CLL panel, ranging from very low (10% normal) to levels found in the other two leukaemias and normal cells. The progressive deviation from normal in the CLL panel is accompanied in all but a minority of patients by the expression of the leucocyte sialoglycoprotein.

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.

Expression of MHC class II antigens in human B-cell leukaemia and non-Hodgkin's lymphoma

In this review we have summarized our experiences of serological analysis of MHC class II antigen expression in human B cell malignant disease. Cells from a large number of cases of B-cell chronic lymphocytic leukaemia (CLL) and non-Hodgkin's lymphoma (NHL) have been examined for expression of class II antigens. Using a number of monoclonal antibodies which in some cases are specific for class II subregion products (DP, DQ and DR), MHC class II antigens were detected by indirect immunofluorescence and fluorescent activated cell sorter analysis in CLL and by immunohistochemical staining in NHL. At the cell surface in many cases of B cell malignant disease, products of the different class II subregion genes are non-coordinately expressed. The most commonly occurring pattern of non-coordinate expression of class II molecules is of expression of DP and DR antigens in the absence of detectable DQ expression. These findings are in contrast to normal B lymphocytes where DP, DQ and DR antigens are expressed together at the cell surface. There is considerable heterogeneity among cases comprising individual histopathological categories of B cell malignancy, and in many instances heterogeneous class II phenotypes are also found on cells from the same tumour. In chronic lymphocytic leukaemia, class II antigen expression is inducible in vitro by treating the cells with the phorbol ester TPA. CLL cells treated with TPA have much increased levels of class II antigen expression at the cell surface and much increased steady state levels of class II specific mRNA transcripts detectable with complementary DNA probes. Aberrant class II antigen expression may be involved in the pathogenesis of B cell malignant disease.

Characterization of chronic lymphocytic leukemia (CLL) cells with low density of surface membrane bound immunoglobulins (smIg)

The study consists of 6 CLL patients with leukemic blood lymphocytes lacking T-cell characteristics and with smIg on only a very small fraction of the cells detected by microscopy or FACS analysis after direct immunofluorescence (IFL) staining. Using B-cell specific monoclonal antibodies all leukemias were found to be of the B-cell type. SmIg, mainly of IgD-class and the monotypic light chain, was detected on a large number of cells in all cases when using direct IFL. No lymphocyte clone was judged to be of the pre-B-cell type or represented fully differentiated terminal B-cells. CLL cells from the individual cases probably represent intermediate B-cell maturation steps. The results lend no support to the suggestion that this subtype of CLL necessarily belongs to an early stage of differentiation just beyond the pre-B-cell level.

Distinctions between endemic and sporadic forms of Epstein-Barr virus-positive Burkitt's lymphoma

Tumour cell lines were established in vitro from 16 cases of Epstein-Barr (EB) virus genome-positive Burkitt's lymphoma (BL), 7 of "endemic" origin (i.e. from holoendemic malarial areas of Africa and of New Guinea) and 9 of "sporadic" origin (i.e. from outside such high-incidence areas). All the BL cell lines thus established were monoclonal by immunoglobulin isotype expression and displayed a characteristic chromosomal translocation, t(8:14) or t(8:22), confirming their malignant origin. Clear differences observed between the individual BL cell lines appeared to be related to their endemic or sporadic status. All 7 endemic cell lines began growth as a carpet of single cells, often with small, loose clumps appearing in later passage. Whilst 3 lines of sporadic origin displayed a similar pattern to the above, the majority of sporadic lines grew as large, tight clumps of cells from the first passage onwards. These differences in growth pattern were reflected by differences in cell surface phenotype, as defined in indirect immunofluorescence tests using a panel of monoclonal antibodies (MAbs) specific for B-lineage-associated antigens. BL cell lines could be classified into 3 separate groups on the basis of their reactivity with 6 particular antibodies (MHM6, AC2, Ki-1, Ki-24, J5 and 38.13). All 7 endemic BL cell lines and 2 of the 3 sporadic BL cell lines which began growth as single cells showed a group-I cell-surface phenotype (MHM6, AC2, Ki-1, Ki-24 negative; J5, 38.13 positive) in early passage. In contrast, all 6 sporadic BL cell lines which began growth in large clumps displayed a distinct group-II phenotype (MHM6, AC2, Ki-1 positive/negative; Ki-24, J5, 38.13 positive); in later passage most of these sporadic lines progressed to a group-III phenotype (MHM6, AC2, Ki-1, Ki-24 positive; J5, 38.13 negative) without loss of those immunoglobulin and chromosomal markers identifying the cells' malignant origin. These clear differences between endemic BL cell lines on the one hand and the majority of sporadic BL cell lines on the other suggest that endemic BL arises from a more restricted range of progenitor B cells than does the sporadic form of the disease.

Acid hydrolase activities in B cell chronic lymphocytic leukaemia lymphocytes: correlation of cytochemical reactions with immunological phenotype

The cytochemical reactions of 5 acid hydrolases, alpha-naphthyl acetate esterase (ANAE), acid phosphatase (AP), beta-glucuronidase, beta-glucosaminidase and dipeptidylaminopeptidase IV (DAP IV) were investigated in lymphocytes from 30 patients with B cell chronic lymphocytic leukaemia (B-CLL). Based on ANAE and AP reactivities, 4 cytochemically distinctive subgroups were identified: Group 1: AP and ANAE less than 50% positive lymphocytes (5 cases); Group 2: AP greater than 50%, ANAE less than 50% positive lymphocytes (11 cases); Group 3: AP less than 50%, ANAE greater than 50% positive lymphocytes (7 cases); Group 4: AP and ANAE greater than 50% positive lymphocytes (7 cases). beta-Glucuronidase displayed similar patterns of reactivity to AP. beta-Glucosaminidase activity was observed in the majority of lymphocytes in most patients, whereas DAP IV activity was present in less than 20% of lymphoid cells. The study failed to establish any relationship between cytochemical grouping and patients' clinical status, peripheral lymphocyte counts, E or mouse rosette values, light or heavy chain cellular immunoglobulin (Ig) class. Attempts to correlate acid hydrolase and Ig heavy chain isotype expression, putative markers of B cell maturation, were unsuccessful and indicate that within the narrow spectrum of B cell differentiation seen in B-CLL these characteristics are unrelated.

Immunoglobulin negative follicle centre cell lymphoma

Immunoglobulin (Ig) could not be detected on the surface or in the cytoplasm of neoplastic cells from five cases of follicle centre cell lymphoma with centroblastic/centrocytic follicular histology when examined by immunohistology of frozen or wax embedded sections. Examination by fluorescein labelled antibodies of cells in suspensions prepared from the biopsies revealed a monotypic surface Ig positive population in one case and a surface or cytoplasmic Ig kappa:lambda light chain imbalance in a further two cases consistent with neoplastic B cell involvement: in all cases the proportion of cells failing to express Ig or T cell markers ranged from 24 to 75%. The monoclonal antibodies B1 (Pan B cell), FMC4 (HLA class II) and J5 (cALL antigen) stained the majority of cells in suspension with residual cells staining with UCHT1 or OKT11 (T cell monoclonal antibodies). In frozen sections, neoplastic follicular cells did not stain with UCHT1. However, in the one case tested these cells stained with the antibodies B1 and FMC4. In paraffin sections J chain could be demonstrated in the cytoplasm of three out of five cases. Cells from four cases were cultured in vitro for Ig production: two failed to produce Ig and monotypic light chains were the sole Ig product of the remaining two cases. The failure to express Ig by the majority of the neoplastic cells from the cases described in this report is at variance with the follicular histology of these neoplasms. Mechanisms responsible for this failure are discussed with reference to current models of B cell differentiation.