Defective expression of T cell antigens in chronic lymphocytic leukaemia: relationship to T cell dysfunction

Absolute CD4 and CD8 counts and CD4-to-CD8 ratios in eight patients with indolent B-cell chronic lymphocytic leukemia

BACKGROUND

There are some patients with B-cell chronic lymphocytic leukemia who exhibit an extraordinary natural resistance to this malignancy, which lasts for many years. In this study, we report the T-cell subset values and ratios in eight such patients.

METHODS

Impath (New York, NY) evaluated immunophenotyping by performing flow cytometry. Absolute CD4 and CD8 counts and CD4:CD8 ratios were performed at Memphis Pathology Laboratory, Memphis, Tennessee.

RESULTS

CD4 and CD8 counts and CD4:CD8 ratios were normal in all eight patients, in contrast to the suppressor cell proliferation and low helper-suppressor ratios that have been previously reported in other patients with B-cell chronic lymphocytic leukemia.

CONCLUSION

These results require further study to determine their significance. Implications for further study are discussed.

Recognition of B-CLL cells experimentally infected with EBV by autologous T lymphocytes

We compared 5-day-old cultures of two B-CLL clones experimentally infected with EBV for their interaction with autologous T lymphocytes. The clone which was strongly activated by the virus stimulated autologous T cells. It was also damaged by the cytotoxic T cells which were generated in mixed cultures with autologous lymphoblastoid cell lines (LCL). Cultured, non-infected CLL cells were not lysed by these effectors. The other B-CLL clone, which was activated to considerably lesser extent by the virus, did not stimulate the autologous T lymphocytes. While, also in this case cytotoxic function was generated in the mixed T cell-LCL culture, the effectors did not damage the EBV-infected CLL cells. The results with B-CLL cells can be regarded as a model for the EBV genome carrier normal B lymphocytes. They substantiate the current concept that such cells persist in seropositive healthy individuals undisturbed by the specific immune response as long as they maintain the phenotype of resting cells. However, after activation they can be recognized and eliminated by T cells.

Altered pattern of cytokine production by peripheral blood CD2+ cells from B chronic lymphocytic leukemia patients

To determine if activation-induced cytokine production is altered in CD2+ lymphocytes from B-CLL patients, cytokine levels were determined by ELISA in supernatants of PHA-stimulated cultures of CD2+ cells from 33 B-CLL patients and 22 healthy controls. The production of Interferon gamma (IFN-gamma) and Tumor Necrosis Factor (TNF-alpha) by mitogen-activated CD2+ lymphocytes from B-CLL patients was higher than that found in healthy controls, while no differences were found in TNF-beta production. IFN-gamma and TNF-alpha levels determined at 72 h in PHA-stimulated CD2+ cell cultures from B-CLL patients statistically correlated with the percentages of CD3+CD45RO+ and CD3-CD56+ lymphocytes, respectively. Although there were differences in the production kinetics of interleukins (ILs) 2 and 4 between B-CLL patients and the healthy controls, no differences were found at the time when the levels of both interleukins peak. The production of both IFN-gamma and IL-4 by PHA-stimulated CD2+ lymphocytes from non-smouldering B-CLL patients was significantly higher than that from smouldering B-CLL patients while no significant differences were found in the production of IL-2, TNF-alpha, and TNF-beta between the two B-CLL patient groups. These data suggest that functional alterations in the production of cytokines by CD2+ cells from B-CLL patients could help to explain the expansion of leukemic cells in B-CLL patients.

Acquired CD40-ligand deficiency in chronic lymphocytic leukemia

Patients with B-cell chronic lymphocytic leukemia (CLL) acquire an immunodeficiency with many characteristics similar to those of persons with inherited defects in the gene encoding the CD40-ligand (CD154). We found that the blood and splenic CD4+ T cells of patients with CLL failed to express surface CD154 after CD3 ligation. However, using an enzyme-linked immunosorbent assay (ELISA)-based quantitative competitive polymerase chain reaction (PCR), we noted that CD3 ligation could induce such T cells to express CD154 messenger RNA at levels similar to that of CD3-activated T cells from normal donors. Moreover, addition of increasing numbers of CLL B cells to activated normal donor T cells rapidly resulted in progressively greater down-modulation of CD154. Such down-modulation of CD154 could be blocked by addition of CD40 monoclonal antibody to cultures in vitro. We propose that leukemia cell-mediated down-modulation of CD154 on activated T cells accounts for some of the acquired immune defects of patients with CLL.

A low blood lymphocyte count is associated with an expansion of activated cytotoxic lymphocytes in patients with B-cell chronic lymphocytic leukaemia

In order to determine the relationships between CD2+ lymphocyte subpopulations and tumour mass, the immunophenotype of natural killer (NK) cells and T lymphocyte subsets was studied in 56 B-chronic lymphocytic leukaemia (B-CLL) patients and 38 healthy subjects. The patients were classified according to their blood lymphocyte count (BLC). Forty patients had BLC<30x10(9)/l (low BLC, less tumour mass) and 16 patients had BLC>30x10(9)/l (high BLC, larger tumour mass). The percentage of CD3- CD56+ cells, as well as of CD8+, CD8+ CD45RO+ and CD3+ CD57+ T subsets in low BLC patients, were higher than those found in high BLC patients. Conversely, the percentages of CD3+ HLA x DR+, CD4+ and CD4+ CD45RO+ lymphocytes were higher in high BLC patients than in low BLC patients. The CD4/CD8 ratio was decreased in low BLC patients while it was increased in high BLC patients and a significant positive correlation was found between their CD4/CD8 ratio and their BLC. We conclude that in low BLC B-CLL patients there is a decreased percentage of activated helper lymphocytes and an increased percentage of NK cells and activated cytotoxic T lymphocytes. These results suggest a role for NK cells, and helper and cytotoxic T lymphocytes in the control of tumour burden in B-CLL patients.

T lymphocyte subpopulations in patients with B-cell chronic lymphocyte leukaemia: relationship to infective episodes

Patients with B-cell chronic lymphocytic leukaemia (B-CLL) have an increased susceptibility to infection. Quantitative abnormalities of T-cells have been previously reported in B-CLL, although the relationship between such abnormalities and the incidence of infection still remains to be established. We therefore enumerated lymphocyte subpopulations in 22 patients with B-CLL grouped according to the number of infective episodes in the previous three years. No significant differences were found between the patient groups and the mean number of T-cells subsets (helper, suppressor, suppressor-inducer and suppressor effector) or NK cells, but patients with frequent infections were found to have significantly higher CD5+ B-cell counts. Thus, we confirm that T-cell subpopulations are numerically altered in patients with B-CLL, but found that such changes are not predictive of susceptibility to infection. Our results however suggest that the malignant B-cells may exhibit immunosuppressive activity.

Hormones and immune responsiveness in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a B cell disorder with multiple abnormalities in T-cell function. The status of the immune system will depend to some extent upon the net effect of the changes in the equilibrium of various hormones. In order to investigate the association of the defects in the cellular immunity and hormonal dysregulation in CLL, studies were performed in 130 CLL patients with that disorder. Decreased lymphocyte proliferation in response to mitogen stimulation appears to be an early event in CLL pathogenesis and is not always influenced by the clinical stage of the disease or the specific treatment. The dysfunction of T-lymphocytes was accompanied by increased serum cortisol (C) concentrations. Elevated levels of follicle stimulating hormone (FSH), luteinizing hormone (LH), 17 beta-estradiol (E) and testosterone (T) ratio were found in male CLL patients, but not in female patients. In view of our findings, it is conceivable that there are a number of disturbances in the lymphocyte-microenvironmental regulation, which may be responsible for immuno-hormonal imbalance in some patients with CLL.

Coexistent cutaneous T-cell lymphoma and B-cell chronic lymphocytic leukaemia

Three patients with cutaneous T-cell lymphoma (CTCL) are reported who had concurrent B-cell chronic lymphocytic leukaemia (B-CLL). The separate lineage and clonal nature of the individual lymphoid malignancies were confirmed by gene-rearrangement analysis. The chronology of the illnesses did not support the hypothesis that CTCL predisposes to the development of B-cell proliferative disorders. There was no clear association with immunosuppressive therapy, and HTLV-1 studies were negative in all patients. Consequently, we speculate that a lymphoid stem cell defect, which may lead to the development of either aberrant B- or T-cell clones, may be responsible for such cases of dual lymphoid neoplasia.

Regulatory aspects of clonally expanded B-1 (CD5+ B) cells

B-1 (CD5+ B) cells appear early in ontogeny, produce mainly unmutated polyreactive antibodies, and are capable of self-renewal. B-1 cells clonally expand with age and are the malignant cell in chronic lymphocytic leukemia. In this report immunological analysis of B-1 malignancies in NZB mice, a murine model of chronic lymphocytic leukemia, is related to current information on B-1 cells. B-1 clones from NZB mice produce high levels of interleukin-10, detected at the RNA level by semi-quantitative polymerase chain reaction. In addition, the B-1 malignant clones in NZB mice and their hybrids, are negative for B220/6B2 expression, the B-specific antigenic form of CD45 which is a membrane-associated phosphatase involved in lymphocyte activation. Both the autocrine production by B-1 cells of interleukin-10 and altered CD45 expression may be responsible for the clonal expansion of these cells, as well as the accompanying T cell expansion. We report the establishment of an in vitro cytotoxic CD8+ T cell line derived from an NZB with a B-1 malignancy. The effect of B-1 cell-derived interleukin-10 on subsets of T lymphocytes may account for the immunoregulatory properties of B-1 cells. In addition, the NZB malignancies were also characterized for immunoglobulin variable region sequence and antigen specificity. The B-1 malignancies produced immunoglobulin derived from unmutated germline sequences with no N base substitutions. It appears that both the immunoglobulin and interleukin-10 produced by the B-1 malignant cell in NZB mice may have immunoregulatory properties. A study of B-1 malignancies may shed light on the immunoregulatory properties of non-clonally expanded normal B-1 cells.

T-lymphocyte response to cytokines in B-chronic lymphocytic leukemia

The mechanisms underlying abnormal T-cell function in B-chronic lymphocytic leukemia (B-CLL) are unknown. We have studied B-CLL T-cell activation pathways in the rigorous absence of leukemic cells and with controlled numbers of accessory cells present. The responsiveness to added recombinant IL-1 and IL-2 was assessed. We have found that under optimal culture conditions B-CLL T cells had a normal PHA-induced proliferative response in terms of incorporated 3H-thymidine per T cell. Also the capacity of mitomycin-C treated B-CLL monocytes to support autologous T-cell mitogenesis was normal. However, a subtle difference between normal and B-CLL T cells emerged with respect to cytokine responsiveness. While the PHA response of purified normal T cells in the absence of monocytes was augmented by rIL-1, this could not be demonstrated for B-CLL T cells. A much greater degree of augmentation occurred with added rIL-2 in the case of both normal and B-CLL T cells. In the presence of 20% autologous monocytes rIL-1 and rIL-2 had no effect on mitogenesis. We conclude that B-CLL T cells have an abnormal profile of cytokine responsiveness which is consistent with observed abnormalities of subset distribution, and which may contribute to the clinical immunodeficiency in B-CLL.

Simultaneous occurrence of cutaneous T cell lymphoma and low-grade B cell lymphoproliferative diseases. A report of two cases

Two previously unreported patients with cutaneous T cell lymphoma associated with systemic low-grade B cell proliferations are presented. The first patient had Waldenström's macroglobulinemia and the second had simultaneous chronic lymphocytic leukemia. The use of immunosuppressive drugs or a genetic predisposition may have contributed to the second malignancy. However, the possibility that malignant helper/inducer T lymphocytes were a factor in the promotion of the proliferation of B cells cannot be excluded.

Immunoregulatory cell dysfunction in chronic B-cell leukemias

Chronic B-cell malignancies are routinely characterized as B-cell clonal diseases that have signs and symptoms primarily related to the continuing expansion of these cells. This review discusses chronic lymphocytic leukemia, multiple myeloma and hairy cell leukemia from the perspective of secondary abnormalities in non-malignant cells. Thus, our main purpose is to elaborate on the alterations/abnormalities of the immunoregulatory (IR) cells in these diseases and focus on the qualitative and quantitative aspects of T-cells, natural killer (NK) cells and monocytes. The relevance of the IR-cell changes to the basic disease process and their complications are emphasized.

T cells and CD45R expression in B-chronic lymphocytic leukemia

A major secondary immunodeficiency exists in B cell derived chronic lymphocytic leukemia (B-CLL) which involves both humoral and cellular immunity and is largely unexplained. Several T cell subset redistributions have been noted in B-CLL. We therefore examined in more detail the immunophenotype of T cells by assessing CD45R expression using a two-colour immunofluorescence technique. The proportion of CD45R+ cells among CD3+, CD4+ and CD8+ cells in B-CLL was significantly (p less than 0.001) higher than in corresponding normal cell populations. We also sought relationships between major T cell subsets and progress of disease and found strongly positive correlations between the total leukocyte count in B-CLL and numbers of CD3+, CD4+, CD8+ cells and monocytes. Further, in patients with clinically more advanced disease, CD3+ and CD4+ cells were present in higher numbers than in patients with less advanced disease (p less than 0.05). CD8+ cells, CD4/CD8 ratio, monocytes and total leukocyte count were not significantly different when comparing the less advanced and more advanced disease patients. An excess of CD45R+ suppressor-inducer T cells has implications for both B and T cell dysfunction and for disease progression.

Dipeptidylaminopeptidase IV activity in T lymphocyte subsets in B cell non-Hodgkin's lymphomas

The total T cell population and T cell subsets in ten lymph nodes with reactive lymphoid hyperplasia (RLH) and 23 specimens (21 lymph nodes, one stomach, and one small bowel) involved by histologically and immunohistologically diagnosed B cell non-Hodgkin's lymphomas (NHLs) were determined by reactivity with monoclonal antibodies Leu 4-CD3, Leu 3-CD4, and Leu 2-CD8 in cytospin preparations from cell suspensions. T cell populations were also investigated for the coexpression of dipeptidylaminopeptidase IV (DAP IV) activity, which was visualized simultaneously with cell surface immunostaining by a combined cytochemical and immunocytochemical method. The mean absolute percentage of Leu 4-CD3+ (total T) and Leu 3-CD4+ cell populations was significantly lower in B cell NHL cases than in RLH cases (35% v 54%, P less than .001; 29.5% v 44.4%, P less than .01). No difference in the mean absolute percentage of the Leu 2-CD8+ T cell subset was found between the RLH cases and the B cell NHL cases classified as other than category A as described by the Working Formulation (WF) of NHLs. The relative percentage of Leu 4-CD3+ and Leu 2-CD8+ cells coexpressing DAP IV reactivity was lower in B cell NHL cases than in RLH cases (27.3% v 39.5%, P less than .05; 13.5% v 24.4%, P less than .10). There was no difference in the proportion of Leu 3-CD4+ cells expressing DAP IV reactivity between the NHL and RLH groups (34.5% v 36.1%). Since the mean relative percentage of Leu 2-CD8+ cells expressing DAP IV reactivity in the B cell NHL group in the other than category A according to the WF was lower than that of the RLH group (12.5% v 24.4%), and whereas the mean absolute percentage of total Leu 2-CD8+ cells was similar in the two groups (16.6% and 16.6%), a possible defective role of this Leu 2-CD8+ DAP IV+ subset, at least in B cell NHLs in the other than category A according to the WF, may be hypothesized.

Unmasking of cryptic natural killer (NK) cell recognition sites on chronic lymphocytic leukemia lymphocytes

The sensitivity of chronic lymphocytic leukemia (CLL) lymphocytes to attack by natural killer (NK) cells has remained questionable. To clarify this issue, freshly isolated lymphocytes of 37 patients with B-CLL, five with WDLL and two with HCL, were tested with a standard cytotoxicity assay with NK cells from normal donors. All these targets were resistant to cytolysis by the effectors. Freeze-fracture analysis of CLL cell plasma membranes revealed that they have a larger number of intramembranous particles (IMP) associated with the external leaflet (E-face) than have normal lymphocytes. Unlike other neoplastic cells, exposure of CLL lymphocytes to phorbol esters or treatment with neuraminidase did not render them vulnerable to attack by NK cells, nor did 5 days of culture have an effect. Incubation of CLL lymphocytes with anti-Ig-mu (24-72 hr) or with 0.1% pepsin (15 min) resulted in 15% and 27% cytolysis, respectively. B-lymphocytes from the blood of healthy donors were not killed when treated similarly: These data establish that freshly isolated B-CLL lymphocytes are resistant to NK cytolysis but that in contrast to normal B-cells, they possess cryptic NK-recognition structures, which may be uncovered by surface modulation.

Abnormal distribution of CD8 subpopulation in B-chronic lymphocytic leukemia identified by flow cytometry

We studied the occurrence of T-cell subpopulations for patients with B-cell chronic lymphocytic leukemia. The CD8+ population was divided into CD8+ suppressor (CD8a+) and CD8+ cytotoxic (CD8b+) lymphocytes using difference in orthogonal light scattering. Average CD4+/CD8+ ratios determined for all patients were decreased. For individual patients this sometimes was not true. In contrast CD4+/CD8a+ ratios were markedly increased in all individual patients. The CD8+ lymphocytes appeared to consist mainly of CD8b+ lymphocytes. Moreover the CD8b+/CD8+ ratio correlated with clinical stage: untreated patients (stage 0 of Rai) have smaller CD8b+/CD8+ ratios than patients with advanced stages of Rai.

Impaired synthesis of immunoglobulin in patients with chronic lymphocytic leukemia

The cause of hypogammaglobulinemia in patients with chronic lymphocytic leukemia (CLL) is unknown. Experiments were performed to determine if sera, monocytes, or non-T cells from patients with CLL suppress the proliferative response and synthesis of immunoglobulin (Ig) following incubation with pokeweed mitogen (PWM) in cocultures with lymphocytes from normal individuals. The data indicate that sera and monocytes from patients with CLL did not suppress the proliferative response or synthesis of Ig normal non-T cells. When various numbers of normal non-T cells and CLL non-T cells were cocultured with a constant number of normal T cells, the proliferative response and the concentration of supernatant Ig decreased as the proportion of CLL non-T cells increased. Since similar results were obtained when irradiated non-T cells from normal individuals were substituted for non-T cells from patients with CLL, we believe that the decrease in proliferative response and diminished synthesis of Ig is not the result of the suppressor non-T cells but is related to the dilution of normal B cells by inert non-T cells. We conclude that these experiments serve as as in vitro model for patients with CLL and suggest that the hypogammaglobulinemia observed in this disease is related to the diluting out of normal B cells by the accumulation of neoplastic B cells in the peripheral blood, bone marrow, and lymphoid tissue of these patients.