Relationship between the capacity to be stimulated of lymphocyte subpopulations and the RAI staging in patients with chronic lymphocytic leukemia]

By means of the incorporation rate of 3H thymidine into the lymphocytes of patients with chronic lymphatic leukaemia the possibility of stimulating them by using different mitogens was checked and compared with normal persons. The examination covered 11 patients treated with extracorporeal irradiation of the blood (ECIB), 5 patients treated with a chlorambucil therapy, and 10 untreated patients who were classified according to the staging system proposed by RAI. The lymphocytes of the peripheral blood were stimulated as mixed and isolated T and B-lymphocytes in the microculture by using the mitogens PHA, PWM, ConA, and LPS. In all CLL patients there was a diminished stimulation rate of a mixed lymphocyte population. A relation existed between the seriousness of the stage and the diminution of the incorporation rate of 3H thymidine. A corresponding correlation could not be identified in untreated CLL patients. Isolated T-lymphocytes revealed better results of stimulation than the total population. As to their function B-lymphocytes showed a dependance on the kind of therapy. In the mixed lymphocyte culture of normal persons the best findings could be observed after stimulation with PHA, that is also valid for CLL patients. PHA, PWA, ConA, and LPS were suitable as substances stimulating B-lymphocytes with different efficacy in normal persons and CLL patients. Both collectives showed the best results in the T-lymphocyte culture after stimulation with LPS.     

The effect of extracorporeal blood radiotherapy on the peripheral blood T and B-lymphocytes in chronic lymphadenitis]

B-lymphocytes and T-lymphocytes were determined before and after therapy in 12 patients with chronic lymphatic leukemia (CLL) treated with extracorporal blood radiation (ECIB). There was a significant decrease of B-lymphocytes (p less than 0.001) from 85.3 +/- 6.55% to 71.55 +/- 10.60% by ECIB, whereas no significant changes could be found in T-lymphocytes. 12 untreated CLL patients, whose B-lymphocytes amounted 83.25 +/- 6.79% with 7.5 +/- 3.42% of T-lymphocytes, were examined as group of comparison. From these findings ECIB is concluded to cause a decrease of accumulated B-cells.     

The simultaneous occurrence of chronic lymphatic leukemia with malignant tumors and the lymphatic reaction caused by malignant growths

In 352 patients affected with chronic lymphatic leukemia (CLL) the authors simultaneously detected a solid second tumour 22 times (= 6.22%) (6 cancers of the prostrate, 5 cancers of the skin, 4 cancers of the uterus, 2 cancers of the stomach, 2 cancers of the lung, one case of rectal and mamma cancer each and one case of eye sarcoma). In one third of the cases the two malignomas were simultaneously detected, thus it was excluded that the second tumour was induced by the antimitotic treatment of the primary disease. In seven cases the solid tumour was identified after diagnosing CLL, without any cytostatic therapy having been made here before. In addition, a report is given on a patient showing symptoms of gastric cancer not radically removed and a lymphocytic reaction. Initially, the case was explained as gastric adenocancer with simultaneous CLL because even 5 years after surgical treatment there were 16-20 X 10(6)/l of leukocytes with 64% of lymphocytes in the peripheral blood and 85% of lympho-reticular cells in the bone marrow. Two years later, however, the blood picture was normal and remained to be unchanged further on. Thus, it seems that the healing of the gastric cancer has caused the lymphocytic reaction to have ceased. In addition, it should be noted that in 1974 the patient suffered from an epithelium after a scratch-mark on the nose tip, which was irradiated, however, without eliciting any lymphocytic reaction. The patient is still alive (June 1985).     

Structure of the inguinal lymph nodes after extirpation of the pancreas

Swiching off the external and internal secretion of the pancreas by means of extirpation of the organ demonstrates a progressive hypoplasia of the immunocompetent tissue in the inguinal lymphatic nodes. The involution is determined by decreasing number of small, middle and large lymphocytes in the cortical part of the node. Together with the decreasing number of the lymphatic nodules, by the 20th-60th days after the operation the germinative centers become poor in middle, large lymphocytes and in lymphoblasts. Among the cells mentioned, mitotic activity is decreased. Hence, thymus-dependent, but to a greater extent, thymus--independent zones of the lymphatic nodes are subjected to involution.     

Stereotypical chronic lymphocytic leukemia B-cell receptors recognize survival promoting antigens on stromal cells

Chronic lymphocytic leukemia (CLL) is the most common leukemia in the Western world. Survival of CLL cells depends on their close contact with stromal cells in lymphatic tissues, bone marrow and blood. This microenvironmental regulation of CLL cell survival involves the stromal secretion of chemo- and cytokines as well as the expression of adhesion molecules. Since CLL survival may also be driven by antigenic stimulation through the B-cell antigen receptor (BCR), we explored the hypothesis that these processes may be linked to each other. We tested if stromal cells could serve as an antigen reservoir for CLL cells, thus promoting CLL cell survival by stimulation through the BCR. As a proof of principle, we found that two CLL BCRs with a common stereotyped heavy chain complementarity-determining region 3 (previously characterized as "subset 1") recognize antigens highly expressed in stromal cells--vimentin and calreticulin. Both antigens are well-documented targets of autoantibodies in autoimmune disorders. We demonstrated that vimentin is displayed on the surface of viable stromal cells and that it is present and bound by the stereotyped CLL BCR in CLL-stroma co-culture supernatant. Blocking the vimentin antigen by recombinant soluble CLL BCR under CLL-stromal cell co-culture conditions reduces stroma-mediated anti-apoptotic effects by 20-45%. We therefore conclude that CLL BCR stimulation by stroma-derived antigens can contribute to the protective effect that the stroma exerts on CLL cells. This finding sheds a new light on the understanding of the pathobiology of this so far mostly incurable disease.     

High Mitochondrial DNA Stability in B-Cell Chronic Lymphocytic Leukemia

Background

Chronic Lymphocytic Leukemia (CLL) leads to progressive accumulation of lymphocytes in the blood, bone marrow, and lymphatic tissues. Previous findings have suggested that the mtDNA could play an important role in CLL.

Methodology/Principal Findings

The mitochondrial DNA (mtDNA) control-region was analyzed in lymphocyte cell DNA extracts and compared with their granulocyte counterpart extract of 146 patients suffering from B-Cell CLL; B-CLL (all recruited from the Basque country). Major efforts were undertaken to rule out methodological artefacts that would render a high false positive rate for mtDNA instabilities and thus lead to erroneous interpretation of sequence instabilities. Only twenty instabilities were finally confirmed, most of them affecting the homopolymeric stretch located in the second hypervariable segment (HVS-II) around position 310, which is well known to constitute an extreme mutational hotspot of length polymorphism, as these mutations are frequently observed in the general human population. A critical revision of the findings in previous studies indicates a lack of proper methodological standards, which eventually led to an overinterpretation of the role of the mtDNA in CLL tumorigenesis.

Conclusions/Significance

Our results suggest that mtDNA instability is not the primary causal factor in B-CLL. A secondary role of mtDNA mutations cannot be fully ruled out under the hypothesis that the progressive accumulation of mtDNA instabilities could finally contribute to the tumoral process. Recommendations are given that would help to minimize erroneous interpretation of sequencing results in mtDNA studies in tumorigenesis.     

Interleukin-6 and interleukin-6 receptor secretion by chronic lymphatic leukaemia and normal B lymphocytes: effect of PMA and PWM

Interleukin-6 (IL-6) and soluble interleukin-6 receptor (sIL-6R) were detected in supernatants of cultures of B chronic lymphatic leukaemia (CLL) lymphocytes. Phorbol-12-myristate 13 acetate (PMA) caused a decrease in the levels of IL-6 in 14 out of 16 cultures and an increase in levels of sIL6R in all 15 cases. The effect of pokeweed mitogen (PWM) was variable and not significant. The levels of IL-6 were below the detection limit (60 pg/ml) in sera of 13 CLL patients whereas sIL-6R was detected (13 ng/ml to 97 ng/ml) in the 13 sera. IL6 was not detected in cultures of unstimulated or stimulated with PMA or PWM normal human B cells. Levels of sIL-6R were minimal in cultures of normal B lymphocytes and were increased in PMA stimulated cultures. The results are consistent with the view that B-CLL cells produce spontaneously IL-6 which could act in an autocrine fashion to cause shedding of surface IL-6R and account for the correlation found between serum levels of sIL-6R and B-CLL lymphocyte numbers. The fall in levels of IL-6 in PMA stimulated CLL cultures might express masking or degradation of IL-6 after combination with the receptor.     

Clinical and Biological Relevance of Genomic Heterogeneity in Chronic Lymphocytic Leukemia

Background

Chronic lymphocytic leukemia (CLL) is typically regarded as an indolent B-cell malignancy. However, there is wide variability with regards to need for therapy, time to progressive disease, and treatment response. This clinical variability is due, in part, to biological heterogeneity between individual patients’ leukemias. While much has been learned about this biological variation using genomic approaches, it is unclear whether such efforts have sufficiently evaluated biological and clinical heterogeneity in CLL.

Methods

To study the extent of genomic variability in CLL and the biological and clinical attributes of genomic classification in CLL, we evaluated 893 unique CLL samples from fifteen publicly available gene expression profiling datasets. We used unsupervised approaches to divide the data into subgroups, evaluated the biological pathways and genetic aberrations that were associated with the subgroups, and compared prognostic and clinical outcome data between the subgroups.

Results

Using an unsupervised approach, we determined that approximately 600 CLL samples are needed to define the spectrum of diversity in CLL genomic expression. We identified seven genomically-defined CLL subgroups that have distinct biological properties, are associated with specific chromosomal deletions and amplifications, and have marked differences in molecular prognostic markers and clinical outcomes.

Conclusions

Our results indicate that investigations focusing on small numbers of patient samples likely provide a biased outlook on CLL biology. These findings may have important implications in identifying patients who should be treated with specific targeted therapies, which could have efficacy against CLL cells that rely on specific biological pathways.     

Rewiring of sIgM-Mediated Intracellular Signaling through the CD180 Toll-like Receptor

Chronic lymphocytic leukemia (CLL) development and progression are thought to be driven by unknown antigens/autoantigens through the B cell receptor (BCR) and environmental signals for survival and expansion including toll-like receptor (TLR) ligands. CD180/RP105, a membrane-associated orphan receptor of the TLR family, induces normal B cell activation and proliferation and is expressed by approximately 60% of CLL samples. Half of these respond to ligation with anti-CD180 antibody by increased activation/phosphorylation of protein kinases associated with BCR signaling. Hence CLL cells expressing both CD180 and the BCR could receive signals via both receptors. Here we investigated cross-talk between BCR and CD180-mediated signaling on CLL cell survival and apoptosis. Our data indicate that ligation of CD180 on responsive CLL cells leads to activation of either prosurvival Bruton tyrosine kinase (BTK)/phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/AKT-mediated, or proapoptotic p38 mitogen-activated protein kinase (p38MAPK)-mediated signaling pathways, while selective immunoglobulin M (sIgM) ligation predominantly engages the BTK/PI3K/AKT pathway. Furthermore, pretreatment of CLL cells with anti-CD180 redirects IgM-mediated signaling from the prosurvival BTK/PI3K/AKT toward the proapoptotic p38MAPK pathway. Thus preengaging CD180 could prevent further prosurvival signaling mediated via the BCR and, instead, induce CLL cell apoptosis, opening the door to therapeutic profiling and new strategies for the treatment of a substantial cohort of CLL patients.     

Humoral immune responses against the immature laminin receptor protein show prognostic significance in patients with chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is characterized by a highly variable clinical course. The role of an autologous tumor-specific immune control contributing to the variable length of survival in CLL is poorly understood. We investigated whether humoral immunity specific for the CLL-associated Ag oncofetal Ag/immature laminin receptor (OFA/iLR) has a prognostic value in CLL. Among sera of 67 untreated patients with CLL, 23 (34.3%) had detectable OFA/iLR Abs that were reactive for at least one specific OFA/iLR epitope. Patients with humoral responses compared with patients with nonreactive sera had a longer progression-free survival (p = 0.029). IgG subclass analyses showed a predominant IgG1 and IgG3 response. OFA/iLR Abs were capable of recognizing and selectively killing OFA/iLR-expressing CLL cells in complement-mediated and Ab-dependent cellular cytotoxicity assays. In the analysis of 11 CLL patients after allogeneic hematopoietic stem cell transplantation, 8 showed high values for OFA/iLR Abs that specifically recognized the extracellular domain of the protein, suggesting a potential role of anti-OFA/iLR-directed immune responses to the graft-vs-leukemia effect in CLL. Our data suggest that spontaneous tumor-specific humoral immune responses against OFA/iLR exist in a significant proportion of CLL patients and that superior progression-free survival in those patients could reflect autologous immune control.     

Effects of extracorporeal blood irradiation on the lymphocyte population in chronic lymphadenosis

The surface markers of lymphocytes were detected in 18 patients with chronic lymphatic leukemia (CLL), with 9 of them being treated by means of extracorporeal blood irradiation (ECIB) and 9 of them being without any treatment. We found that B-lymphocytes were eliminated by ECIB to a higher degree than it can be recognized by the decrease of lymphocytes. As to their percentage B-cells with ME-receptors or EAC-receptors respectively were partially diminished to a higher degree than the total population of B-cells. Moreover, the pathological Ig-type could be shown to be affected predominantly. The changes of marker profiles and absolute values achieved by ECIB revealed an approach of values in treated patients to those of untreated patients. The investigations make it clear that the determination of lymphocyte subpopulation can be used not only for diagnosis and differential diagnosis of lymphatic system diseases, also for evaluating therapy effects.     

Mitogen activation of human chronic lymphatic leukemia cells. I. Synthesis and secretion of immunoglobulin.

The response of CLL (chronic lymphatic leukemia) lymphocytes to PHA, PWM, and Con A with respect to changes in surface markers and synthesis and secretion of immunoglobulin were examined. After PHA stimulation the percentage of cells bearing readily detectable surface immunoglobulin (SmIg) diminished rapidly whereas cells forming rosettes with sheep erythrocytes (E-rosettes) increased from less than 1% to 30 to 50%. The great majority of blast-transformed cells were E-rosette-positive cells with a small population of SmIg-positive blast cells also observed. Ig production in four of seven CLL lymphocyte populations was increased 2.5 to greater than 40-fold after 4 to 6 days of culture in the presence of PHA. In contrast, pokeweed mitogen did not affect Ig synthesis. Furthermore, the Ig secreted into the culture supernatant fluids from seven of eight CLL cases examined consisted almost entirely of free light chain molecules. In contrast, the cell lysates contained a significant proportion of intact Ig molecules. These results indicate that CLL cells can, under certain circumstances, be stimulated to synthesize and secrete increased amounts of Ig, but that there is a basic defect in the biosynthetic mechanism of these cells which result in the secretion of free light chains rather than intact immunoglobulin molecules.     

Elucidating the CXCL12/CXCR4 Signaling Network in Chronic Lymphocytic Leukemia through Phosphoproteomics Analysis

Background

Chronic Lymphocytic Leukemia (CLL) pathogenesis has been linked to the prolonged survival and/or apoptotic resistance of leukemic B cells in vivo, and is thought to be due to enhanced survival signaling responses to environmental factors that protect CLL cells from spontaneous and chemotherapy-induced death. Although normally associated with cell migration, the chemokine, CXCL12, is one of the factors known to support the survival of CLL cells. Thus, the signaling pathways activated by CXCL12 and its receptor, CXCR4, were investigated as components of these pathways and may represent targets that if inhibited, could render resistant CLL cells more susceptible to chemotherapy.

Methodology/Principal Findings

To determine the downstream signaling targets that contribute to the survival effects of CXCL12 in CLL, we took a phosphoproteomics approach to identify and compare phosphopeptides in unstimulated and CXCL12-stimulated primary CLL cells. While some of the survival pathways activated by CXCL12 in CLL are known, including Akt and ERK1/2, this approach enabled the identification of additional signaling targets and novel phosphoproteins that could have implications in CLL disease and therapy. In addition to the phosphoproteomics results, we provide evidence from western blot validation that the tumor suppressor, programmed cell death factor 4 (PDCD4), is a previously unidentified phosphorylation target of CXCL12 signaling in all CLL cells probed. Additionally, heat shock protein 27 (HSP27), which mediates anti-apoptotic signaling and has previously been linked to chemotherapeutic resistance, was detected in a subset (∼25%) of CLL patients cells examined.

Conclusions/Significance

Since PDCD4 and HSP27 have previously been associated with cancer and regulation of cell growth and apoptosis, these proteins may have novel implications in CLL cell survival and represent potential therapeutic targets. PDCD4 also represents a previously unknown signaling target of chemokine receptors; therefore, these observations increase our understanding of alternative pathways to migration that may be activated or inhibited by chemokines in the context of cancer cell survival.     

Resumption of ovarian follicular activity and uterine involution in the postpartum llama

Resumption of ovarian follicle activity and uterine involution was studied in the post partum llama. Thirty-nine adult multiparous llamas were monitored by ultrasonography and analysis of urinary estrone sulfate for 30 d post partum at the La Raya Research Station in Peru. Uterine involution was measured in terms of reduction of length and diameter of both uterine horns. Correlation analysis was used to relate follicle size and concentration of estrone sulfate. Analysis of variance was used to determine rate of uterine involution relative to days post partum. The left ovary was palpated and scanned by Day 3 post partum in contrast to Day 1 post partum for the right ovary. Ovulatory size follicles, 7 mm, were present by Day 7.4 post partum (range 4 to 14 d). Follicle growth was detected as early as Day 4 post partum with follicle size being less during the first follicle wave (7.4 mm) compared to the second and third waves (9 to 10 mm). Concentrations of urinary estrone sulfate were positively related (P<0.05) to follicular size, but to a lesser degree during the first follicle wave (19.4 ng/mg Cr), than to the second wave (25.4 ng/mg Cr). Uterine involution, as measured by diameter, was different between the left (gravid) and right (nongravid) uterine horn (P<0.05) for the 17 d post partum, and was also different from that of control females for the 21 d post partum. Uterine involution was complete in 63% of females by Day 21 post partum.     

Serum haptoglobin types and leukemia

Summary Haptoglobin types were determined on 211 patients with leukemia of the four most common types: acute lymphatic (ALL), chronic lymphatic (CLL), acute myeloid (AML), and chronic myeloid leukemia (CML). Frequency distributions of the three common Hp types in patients differed significantly from the control population. A significant increase in the relative incidence of Hp 1-1 was observed in patients with ALL, AML, and CML, but not with CLL. A similar trend was consistant in the data from previously published studies for the same three types of leukemia but not for CLL. Our results and the analysis of data from previous studies, suggest an association of Hp type with some leukemias, which is expressed in a consistent elevation of Hp 1-1 type among leukemia patients with ALL, AML, and CML.     

Evidence for a shift from IgD to IgA synthesis in the maturation of human B lymphocytes.

A case of chronic lymphatic leukemia (CLL) is described in which IgD and IgA are the copredominant membrane immunoglobulins. Since CLL represents malignant proliferations of B lymphocytes arrested at discrete points during maturation, the findings in this case suggest that at least some of the developing cells destined to synthesize IgA for secretion pass through a stage in which immunoglobulins D and A are present together on the cell membrane.     

Identification and quantitation of human T-cell antigen by antisera purified from antibodies crossreacting with hemopoietic progenitors and other blood cells

Anti-T cell globulin (ATCG) prepared from antihuman thymocyte serum by absorption with kidney, cells from patients with chronic lymphatic leukemias, and several lymphoblastoid cell lines was shown to react specifically with human thymus-derived lymphocytes. While high activity against thymocytes and a T-lymphoblastoid cell line could be demonstrated, ATCG remained negative against several chronic lymphatic leukemias and B-lymphoblastoid cell lines. The ATCG was used in the cytotoxic test, electronmicroscopy, and immunoautoradiography for identification of T cells in thymus, tonsils, spleen, blood, bone marrow, lymphatic leukemias, and lymphoblastoid cell lines. A comparison of these results with the ability to form spontaneous SRBC-rosettes revealed remarkable deviations between both markers in leukemias. Absorption with human brain failed to remove specific activity of ATCG. Labeling experiments by immunoautoradiography and investigations by complement fixation permitted quantitation of relative T-cell antigen concentration on different cell populations. As further evidence for specificity it could be shown that ATCG was no longer toxic for hemopoietic progenitors, whereas unabsorbed globulin reduced the number of colonyforming cells considerably.Abbreviations ALL acute lymphatic leukemia - ATCG anti-human T cell globulin (absorbed) - ATG anti-human thymocyte globulin (not absorbed) - Bm-C bone marrow cells - CFA complete Freund's adjuvant - CLL chronic lymphatic leukemia - EBV Epstein-Barr virus - GPC' guinea pig complement - HBSS Hanks' balanced salt solution - Ig immunoglobulin - PBS phosphate buffered saline - Per-Ly peripheral blood lymphocytes (normal) - Spl-Ly spleen lymphocytes - SRBC sheep red blood cells - VBS veronal buffered saline - Thy-Ly thymus lymphocytes - Ton-Ly tonsil lymphocytes     

On CK2 regulation of chronic lymphocytic leukemia cell viability

Specific inhibition of signaling elements essential for the viability of B-cell chronic lymphocytic leukemia (CLL) cells offers great promise for the design of more efficient therapies. The protein serine/threonine kinase CK2 is frequently upregulated in cancer, and it is overexpressed and hyperactivated in primary CLL cells from untreated patients. We have shown that inhibition of CK2 induces apoptosis of CLL cells, whereas it does not significantly impact normal lymphocytes, demonstrating the selectivity of the CK2 inhibitors toward leukemia cells. Notably, although co-culture with OP9 stromal cells and BCR stimulation both promote leukemia cell survival in vitro, they do not prevent apoptosis of CLL cells treated with CK2 inhibitors. PI3K signaling pathway was previously shown to be essential for CLL cell viability, an observation we confirmed in all patient samples analyzed. Further, we observed that CK2 blockade decreases PTEN phosphorylation, leading to PTEN activation, and that apoptosis of CLL cells upon CK2 inhibition is mediated by PKC inactivation. This suggests that activation of PI3K/PKC signaling pathway is involved in the pro-survival effects of CK2 in CLL cells. Sensitivity to CK2 inhibition does not correlate with expression of ZAP-70 or CD38, or with IGVH mutation status. However, it positively correlates with the percentage of CLL cells in the peripheral blood, β2 microglobulin levels, and Binet clinical stage. CK2 appears to play an important role in the biology of CLL and constitutes a promising target for the development of leukemia-specific therapies.     

Patterns and predictors of referral to the specialized chronic lymphocytic leukemia clinic in Manitoba,Canada

BackgroundBetter CLL patient survival has been reported for specialized CLL clinics/hematologists (compared to other CLL patients). It is possible that improved survival is driven by a better prognosis of referred patients.MethodsWe used logistic regression to calculate the odds ratios (ORs) and 95 % confidence intervals 95 %CIs) of the association between patient characteristics and CLL referral of all persons diagnosed in 2005–2016 with a pathologically-confirmed CLL or SLL.ResultsTwo-thirds of 1293 patients were referred to the CLL clinic. Referred patients were younger (16 % vs 44 % were 80 +) and in better health (47 % vs 56 % with a chronic diseases) than non-referred patients. Referral increased over time: in 2005–2010, about 60 % of patients were referred; in 2011–2016, this increased to 76 %. Gender did not affect referral (the OR for females is 1.0, 95 %CI 0.8–1.2), but age played a major role; CLL patients diagnosed at age 80 + were less likely to be referred than patients diagnosed < 60, 0.2 (0.1–0.3).ConclusionBecause referral to Manitoba’s specialized CLL clinic is associated with age and the patient’s overall health before referral, one should be careful in interpreting differences in outcomes between CLL patients based on referral status alone.     

Quantitative monitoring of lymphoid malignancies. Application and findings in chronic lymphocytic leukemia

The present study investigated the surface immunoglobulin (Ig) phenotypic pattern in 64 cases of chronic lymphocytic leukemia (CLL). The fluorescence activated cell sorter techniques were modified to provide sensitive and highly reproducible detection and quantification of the otherwise faint surface immunoglobulins on the cells in CLL. In over 98% of the cases of CLL, light chain of the surface Ig could be identified and measured. Serial measurements were shown to be highly reproducible. The phenotypic pattern and density identified on the surface of the circulating lymphocytes precisely reflected the findings in any given patient when other lymphoid tissue (bone marrow, lymph node or spleen) was sampled. Intraclonal heterogeneity detected by surface Ig was seen in some cases of CLL in spite of a relatively uniform morphology by other classical techniques. Three patterns of cell-to-cell variation were seen: 1) that of a non-Gaussian distribution of surface light Ig staining intensity 2) that of the presence of increased surface light Ig chain on a portion of the cells with a subpopulation of CLL cells showing an additional class of heavy chain, and 3) that of anisotropy where the surface Ig quantitatively did not correlate with cell size. Immunoglobulin phenotypic characterization of the cases of CLL was correlated with their clinical stage of disease activity. The distribution of surface light chain phenotype did not relate to any pattern of clinical stage of activity of the disease. By contrast, cases where the cells had a predominance of surface IgM were associated with a more advanced stage of CLL and a poorer clinical prognosis. When surface IgG was predominant, a lesser degree of clinical activity of disease was identified. The phenotypic pattern of the surface Ig on the lymphocytes in CLL mirrors the pattern of differentiation in the murine model of B-cell differentiation, and clinical aggressiveness appears to correlate with the character and degree of B-cell differentiation.