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Malignant CD4+ T cells in adult T-cell leukemia/lymphoma (ATL) and cutaneous T-cell lymphoma (CTCL) express a number of cell surface molecules that are upregulated on normal T cells activated by foreign antigen. In this report we describe an interesting exception to the parallel phenotypic features of activated T cells and malignant CD4+ T cells. A monoclonal antibody (MoAb; termed 27.2) that was raised to HTLV-1+, CD4+25+ leukemic T cells stained weakly 25% of peripheral T cells, including approximately 50% of CD8+ T cells and 20% of CD4+ T cells. Flow cytometry analysis indicated that the surface density of the 27.2 antigen was unchanged or diminished when normal T cells were activated by antigen. However, 3/4 Sezary cases and 4/8 cases of ATL had relatively high densities of the 27.2 antigen. Immunoprecipitation and sodium dodecylsulfate polyacrylamide gel electrophoresis of the NP-40-solubilized membranes of surface-iodinated ATL cells indicated that MoAb 27.2 reacted with a 75 Kd molecule. The size and distribution of the 27.2 antigen on T cell subsets suggested that it might be the enzyme ecto-5ʹ nucleotidase (NT), a phosphatidylinositol-linked enzyme that catalyzes dephosphorylation of monophosphate nucleotides to their respective nucleosides. This was confirmed by demonstrating that lymphocyte ecto-5ʹNT activity was blocked partially and inhibited completely by preincubating cells with MoAb 27.2 for 1 hour at 4°C and 24 hours at 37°C, respectively. When used with a second MoAb (27.1) to a novel T cell activation antigen found on all CTCL and ATL leukemias examined, 27.2 was found to discriminate between normal and leukemic T cells in two patients with ATL. These studies suggest that ecto-5ʹNT has diagnostic value in T cell malignancies and may be aberrantly expressed in some cases of ATL and CTCL.

Interferon (IFN)-αinhibits DNA synthesis stimulated by low molecular weight B-cell growth factor (BCGF) in hairy cells in vitro, suggesting that the therapeutic efficacy of IFN-αin hairy cell leukemia (HCL) involves growth inhibition of malignant B cells. Evidence that the 16-Kd cell surface protein Leu-13 mediates an antiproliferative signal in T lymphocytes and is IFN-inducible in endothelial cells prompted us to examine the expression and functional role of this molecule in leukemic B cells. Leu-13 density, determined by flow cytometry, was upregulated in vitro and in vivo by IFN-αon malignant B cells from patients with HCL, chronic lymphocytic leukemia, and prolymphocytic leukemia. Monoclonal anti–Leu-13 triggered homotypic aggregation of leukemic B cells via an adhesion pathway that was not inhibited by antibodies to leukocyte function associated antigen-1 (LFA-1) or intercellular adhesion molecule-1 (ICAM-1). Moreover, anti–Leu-13 potentiated the inhibitory effects of IFN-αon BCGF-stimulated DNA synthesis, assessed by [3H]-thymidine and [3H]-deoxyadenosine incorporation into DNA. These results indicate that Leu-13 is part of a novel IFN-inducible signaling pathway which may modify the growth and adhesive properties of leukemic B cells under physiologic or therapeutic conditions.

Leukemic cells in 134 patients with ALL were analyzed by a panel of mouse monoclonal antibodies. Two antibodies are reactive with all peripheral blood T cells but define different surface antigens (Leu-1 and Leu-4). Two other antibodies react with antigens that are restricted to suppressor/cytotoxic T cells (Leu-2) and to helper T cells (Leu-3). We also used antibodies to the receptor for sheep red blood cells (SRBC) (Leu-5) and to a human “TL-like” antigen that is found on most thymocytes but not in peripheral T cells (Leu-6). An antibody to the human p29,34 “la-like” molecule was also tested. Of the 134 ALL patients, 17 had a predominance of SRBC-rosetting (Leu-5 +) lymphoblasts (“T” ALL), expressing different surface phenotypes defined by this panel of monoclonal antibodies. These phenotypes were not readily classifiable according to a scheme of sequential stages of normal differentiation proposed. Moreover, the lymphoblasts in 8 of 113 patients not expressing conventional B- or T-cell markers (“null” ALL) reacted with the monoclonal anti-T-cell antibodies. This study suggests that the classification of lymphoblasts in ALL based on the reactivities observed with this panel of mouse monoclonal antibodies is not easily reconciled with current models of normal T-cell differentiation. However, it should be emphasized that the precise sequence of antigenic expression by cells undergoing thymic differentiation is still not fully known, and further phenotypic analysis of ALL cells might contribute to an improved understanding of this malignancy.

The ability of peripheral blood mononuclear cells (PBMC) to produce and respond to interleukin-2 (IL-2) was evaluated in 50 recipients of HLA-identical bone marrow (BM) depleted of mature T cells by soybean agglutination and E rosetting (SBA E BM). In contrast to our previous findings in recipients of unfrectionated marrow, during weeks 3 to 7 post-SBA E BM transplantation (BMT), PBMC from the majority of patients sponteneously released IL-2 into the culture medium. This IL-2 was not produced by Leu-11+natural killer cells, which were found to be predominant in the circulation at this time, but by T11+, T3+, la antigen-bearing T cells. The IL-2 production could be enhanced by coculture with host PBMC frozen before transplant but not by stimulation with mitogenic amounts of OKT3 antibody, thus suggesting en in vivo activation of donor T cells or their precursors by host tissue. Spontaneous IL-2 production was inversely proportional to the number of circulating peripheral blood lymphocytes and ceased after 7 to 8 weeks post-SBA–E–BMT in most of the patients. In patients whose cells had ceased to produce IL-2 spontaneously or never produced this cytokine, neither coculture with host cells nor stimulation with OKT3 antibody thereafter induced IL-2 release through the first year posttransplant. Proliferative responses to exogenous IL-2 after stimulation with OKT3 antibody remained abnormal for up to 6 months post-SBA–E–BMT, unlike the responses of PBMC from recipients of conventional BM, which responded normally by 1 month post-BMT. However, the upregulation of IL-2 receptor expression by exogenous IL-2 was found to be comparable to normal controls when tested as early as 3 weeks post-SBA–E–BMT. Therefore, the immunologic recovery of proliferative responses to IL-2 and the appearance of cells regulating in vivo activation of T cells appear to be more delayed in patients receiving T cell–depleted BMT. Similar to patients receiving conventional BMT, however, the ability to produce IL-2 after mitogenic stimulation remains depressed for up to 1 year after transplantation. © 1987 by Grune & Stratton, Inc.

The development of T lymphocytes in 34 patients engrafted with allogeneic bone marrow was studied by indirect immunofluorescence using mouse monoclonal antibodies. Two antibodies, termed anti-Leu-1 and anti-Leu-4, react with distinct membrane components expressed by all peripheral T cells, whereas two other antibodies, termed anti-Leu-2a and anti-Leu-3a. react with complementary subsets of Leu-1 + and Leu-4+ lymphocytes. The Leu-2a + 3a– (Leu-2) subset contains suppressor/cytotoxic T cells, and the Leu-2a – 3a+ (Leu-3) subset contains helper T cells. The ratio of Leu-2/Leu-3 T cells was elevated in nearly all patients studied during the first month of engraftment, but this ratio subsequently returned to normal in patients with an uncomplicated course or with solved acute GVHD. In contrast, a deficiency of helper T cells with a resultant preponderance of suppressor/ cytotoxic T cells persisted in all patients studied with both acute and chronic GVHD after the first month. The implications of these findings in regard to the functions of these cells in vitro are discussed.

The anti-D antibody of two human sera was found to be transferred in part from sensitized group A Rh (D)-positive cells to normal group B Rh (D)-positive cells when the cell suspensions were mixed and incubated in a saline medium. The amount of anti-D antibody transferred from sensitized to normal cells in a given period of time was found to be directly related to the concentration of antibody to which the group A donor cells were originally exposed. It is concluded that the amount of antibody transferred to recipient cells under standard conditions is related to the concentration of antibody on the surface of the donor cells.

A male, 47, developed chronic hemolytic anemia in association with high titers of cold agglutinins in 1966. His symptoms of the cold agglutinin syndrome began in 1951 with cyanosis of the extremities and face after exposure to cold. In 1956, hemoglobinuria was first noted after chilling. In 1962, the cold agglutinin titer was 1:16,000, and his red cells were coated with complement globulins. In 1966, he developed chronic hemolytic anemia and a macroglobulin M component appeared in the serum protein electrophoresis. The titer of cold agglutinins was 1:64,000. The hemolytic anemia responded to chlorambucil with a decrease in cold agglutinin titer and the level of macroglobulin. Serum complement (C) values returned toward normal. Cessation of chlorambucil was followed by relapse. There was a second response to chlorambucil, but reactivation of the hemolytic anemia occurred following a respiratory infection, despite the reduced titer of cold agglutinin. Chlorambucil was discontinued and has not been administered since. There have been remissions and exacerbations of the hemolytic anemia and a return of the macroglobulin and cold agglutinins toward pretreatment levels. During the past 2 yr there has been spontaneous improvement in his symptoms, and the level of macroglobulin has decreased. Despite the appearance of a monoclonal macroglobulin having kappa light chain and with cold agglutinin activity, there is reason to classify his abnormal immunoglobulin production as benign.

1. Observations of 11 patients with acquired hemolytic anemia are reported.