E-rosette formation in B-cell lymphatic leukemias induced by binding activity of monoclonal surface immunoglobulins to sheep red blood cells

Aberrant expression of T-cell-associated antigens on B-cell non-Hodgkin lymphomas

We describe 9 well-characterized cases of B-cell non-Hodgkin lymphoma (NHL) that showed aberrant expression of T-cell-associated antigens by 2-color flow cytometry. Cases were as follows: chronic lymphocytic leukemia/small lymphocytic lymphoma, 4; follicle center cell lymphoma, 2; mantle cell lymphoma, 1; and diffuse large B-cell lymphoma, 2. CD2 was the most commonly expressed antigen (5 cases). CD8 and CD7 were identified in 2 cases each, including 1 case that expressed both CD7 and CD4. The disease course and response to treatment were compatible with the type and stage of lymphoma. No unusually aggressive behavior was noted in any case. A control group of 59 cases of benign lymph nodes analyzed during the same period showed no aberrant expression of T-cell-associated antigens; thus, such expression is not a feature of benign lymphoid proliferations. Study of these B-cell lymphomas may prove invaluable to study aberrant activation of silent or repressed T-cell differentiation genes. CD2-expressing B-cell NHLs may represent clonal expansion of CD2+ B lymphocytes that normally constitute a small fraction of peripheral B lymphocytes and should not be confused with composite B- and T-cell lymphomas. Unless aggressive behavior is noted consistently, no aggressive treatment is justified.

B-cell chronic lymphocytic leukaemia with aberrant expression of CD8 antigen

The monoclonal antibodies against CD8 (T suppressor/cytotoxic) antigen (Leu2/OKT8) were found to bind to leukaemic lymphocytes from a patient with chronic lymphocytic leukaemia. The cells also had an unusual type of rod-like cytoplasmic immunoglobulin of IgM/lambda type as seen by light, fluorescence and electron microscopy, and displayed several antigens characteristic for B lymphocytes. Gene rearrangement analysis showed rearrangement of mu heavy chain gene. In spite of an expression of CD8 antigen, T-cell receptor genes were not rearranged.

A monoclonal surface immunoglobulin (IgM/D-L) with specificity for surface antigen of ox red blood cells in a patient with leukemic lymphosarcoma

A patient with B-cell leukemic lymphosarcoma, whose lymphocytes had a monoclonal (IgM/D-L) surface immunoglobulin (SmIg) and formed rosettes with ox red blood cells (ORBC), is described. The leukemic cells were documented to have a monoclonal SmIg and cytoplasmic Ig (CIg) and secreted a monoclonal immunoglobulin (MIg) whose antibody activity was directed to the surface antigen of ORBC. Pretreatment of the leukemic cells with anti-mu, anti-delta, or anti-lambda inhibited E(ox) rosette formation specifically. Pretreatment of the leukemic cells with pronase removed the SmIg and abolished E(ox) rosette formation simultaneously, and regeneration of the SmIg was parallel with recovery of the rosette formation. A small amount of serum MIg could be detected by agarose gel electrophoresis and antiidiotypic antibody against the 19 S component of the serum revealed that the monoclonal SmIg, CIg, and serum MIg shared the same idiotope. This case suggests that lymphocytes of some B-cell malignancies may bind to ORBC through SmIg.

B-prolymphocytic leukemia cells that form rosettes with sheep red blood cells through monoclonal surface immunoglobulin

The neoplastic cells from a patient with B-cell prolymphocytic leukemia exhibited sheep red blood cell (SRBC) rosette formation. Immunochemistries revealed no reactivity with T-cell monoclonal antibodies OKT 3, 4, 8, and 11. However, the neoplastic cells expressed characteristics of B-cells including surface IgM and IgD associated with lambda light chains, Ia-like antigenicity, and reactivity to monoclonal antibodies against B-cell antigens B1, B2, and B4. Inhibition procedures revealed that SRBC rosette formation was the result of binding activity of surface immunoglobulin to SRBC. Pretreatment of the leukemic cells with antihuman IgM or lambda antisera, or pronase or trypsin blocked rosette formation with SRBC. Circulating antibody to SRBC was also suspected by the fact that preincubation of SRBC with heat-inactivated patient's serum resulted in agglutination of the SRBC.

Imbalances of T-cell subsets in monoclonal gammopathies

In 42 patients with untreated or treated multiple myeloma (MM) or benign monoclonal gammopathy (BMG) the lymphocytes and T lymphocyte subsets were determined by monoclonal antibodies and other surface markers. In untreated MM, the T cells (1077/microliters vs 1439/microliters, P less than 0.01) and especially the OKT4+ lymphocytes (700/microliters vs 950/microliters, P less than 0.05) were significantly reduced compared with a control group. The OKT8+ cells were slightly but not significantly decreased. In previously treated MM, the loss of T cells was more pronounced than in the untreated group and was primarily caused by a further reduction of OKT4+ cells. Patients with BMG revealed decreased OKT8+ lymphocytes (304/microliters vs 502/microliters, P less than 0.001), whereas the OKT4+ cells were within the normal range. Therefore, the OKT4/OKT8 ratio was significantly elevated compared with that in untreated MM patients and normal controls (3.31 vs 2.06 vs 2.13; P less than 0.005). To sum up, in MM the results revealed a reduction of T cells, mainly of OKT4+ cells, which is intensified by chemotherapy and persists even after a long therapy-free interval. The different findings of T cell subsets in BMG and MM may be a helpful criterion to differentiate between BMG and MM.

T gamma (T gamma) cells suppress growth of erythroid colony-forming units in vitro in the pure red cell aplasia of B-cell chronic lymphocytic leukemia

In vitro studies were performed in two patients with B-cell chronic lymphocytic leukemia who developed pure red cell aplasia (CLL-PRCA). During the active phase of their red cell aplasia, there was a marked reduction in the numbers of erythroid colony-forming units (CFU-E). Unfractionated sera or separated IgG fractions from these patients did not impair CFU-E proliferation from either autologous or allogeneic marrows. Increased numbers of T lymphocytes were present in marrow aspirates of these patients. Analysis of these T cells indicated that 90 and 35%, respectively, bore Fc receptors for IgG (T gamma cells). Removal of T cells by E-rosetting techniques augmented CFU-E growth in CLL-PRCA 10-fold. Similar treatment of normal marrows did not cause similar enhanced growth of CFU-E. Co-cultures of marrow T cells or T gamma cells obtained during the active phase of CLL-PRCA suppressed CFU-E growth from autologous or allogeneic marrows. After achieving drug-induced remission of the PRCA, marrow T cells were no longer inhibitory. In contrast, BFU-E (erythroid burst-forming units) or granulocyte proliferation in diffusion chambers were not suppressed by CLL-PRCA T cells. These findings suggest that the development of PRCA in B-cell CLL may result from suppression of CFU-E proliferation by T gamma cells.

Binding of sheep erythrocytes in chronic lymphocytic leukemias of B-cell origin

Two patients with B chronic lymphocytic leukemia having leukemic cells that bind sheep red blood cells by different mechanisms are described. In the first case, rosette formation was mediated by the anti-sheep erythrocyte activity of a monoclonal surface IgMk, related to Forssman antigen. In the second, E-rosette formation was found to be independent of both surface immunoglobulins and the classic E-rosette receptor since the leukemic cells were recognized neither by the OKT-11 monoclonal antibody nor by other markers specific to T-cell lineage. Evaluation of these rare cases emphasizes that detection of surface immunoglobulins and spontaneous rosetting are not sufficient for the characterization of leukemic clones and raises some doubts concerning the use of available surface markers in the characterization of lymphoproliferative disorders.

Expression of Ia-like antigen in lymphatic leukaemias and non-hodgkin lymphomas in correlation with other surface markers

Ia-like antigen, surface Ig, E-rosettes, mouse red blood cell rosettes and further surface markers were investigated in 88 specimens from 69 patients with various lymphocytic leukaemias and non-Hodgkin lymphomas. Ia-like antigen was detectable in all cases of sIg+ leukaemias and lymphomas. E-Ia+sIg-leukaemias, especially CLL and lymphomas were interpreted as B-cell neoplasias, which either did not produce sIg or expressed it in undetectable amounts. E+Ia+sIg+ malignant lymphocytes represented a B-cell population with antibody activity of sIg to SRBC. In the present series 9.5% of all B-cell leukaemias and lymphomas demonstrated this phenotype. Whereas ALL may possess Ia-like antigen, the vast majority of mature T-cell lymphomas are lacking it. In the present series 2 T-cell lymphomas expressed Ia-like antigen and did not contain TdT (E+Ia+sIg-TdT-). These lymphomas are probably derived from a stimulated T-cell clone synthesizing Ia-like antigen.