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By searching the expressed sequence tag (EST) database, we identified partial cDNA sequences encoding a polypeptide with significant sequence identity to the human CC chemokine macrophage-inflammatory protein-1 alpha (MIP-1 alpha)/LD78 alpha. We determined the complete cDNA sequence that contained a reading frame of 89 amino acids with 61% identity to human MIP-1 alpha/LD78 alpha. The mRNA was expressed constitutively at high levels in human lung and at low levels in some lymphoid tissues. Furthermore, the mRNA was strongly induced in several human cell lines, including monocytic U937 cells, by PMA. From these results, we designated this novel CC chemokine as PARC from pulmonary and activation-regulated chemokine. In situ hybridization analyses showed that alveolar macrophages, follicular dendritic cells in the germinal centers of regional lymph nodes, and peripheral blood monocytes stimulated with LPS express PARC mRNA. Using the human CC chemokine yeast artificial chromosome contig that we constructed recently, we mapped the PARC gene (SCYA18) within one of the two subregions of the CC chemokine gene cluster at chromosome 17q11.2. To investigate its biologic activity, the PARC protein was expressed in insect cells. PARC was chemotactic for both activated (CD3+) T cells and nonactivated (CD14-) lymphocytes, but not for monocytes or granulocytes. Binding analysis using PARC fused with alkaline phosphatase-(His)6 showed the presence of a single class of receptors for PARC on lymphocytes with a Kd of 1.9 nM and 590 sites/cell. Thus, PARC is a novel CC chemokine with a close phylogenic relationship with MIP-1 alpha/LD78 alpha, but with a highly selective activity on lymphocytes.

Peripheral blood T lymphocytes obtained from two patients with paroxysmal nocturnal hemoglobinuria (PNH) were immortalized with human T-lymphotropic virus type 1 (HTLV-1). These cells showed interleukin-2 (IL-2)-dependent cell growth in culture. Cell surface analysis showed that they had the phenotype of a helper/inducer T subset that was positive for CD2, CD3, and CD4, but negative for CD8, similar to adult T-cell leukemia cells induced by HTLV-1. These cell lines lacked glycosylphosphatidylinositol (GPI)-anchored proteins, CDw52, CD55 (decay-accelerating factor; DAF), and CD59 on the cell surface, whereas intracellular DAF protein was detected. These T-subset cell lines with a PNH phenotype did not synthesize GPI anchor, whereas a control cell line, similarly prepared from the T cells of a healthy volunteer, produced the anchor. The control cells expressed CDw52, DAF, and CD59 on the cell surface and showed the phenotype of a helper/inducer subset. Southern blot analysis confirmed the clonality of each cell line. These CD4+ T-cell lines with a PNH phenotype and a subset-matched control counterpart could be a useful model for PNH investigation.

The ocular manifestation of human T-cell lymphotropic virus type I (HTLV-I) infection has been recognized as a new clinical entity termed HTLV-I uveitis. In order to determine whether HTLV-I uveitis is associated with lymphocyte alveolitis, bronchoalveolar lavage (BAL) was carried out in 11 patients with HTLV-I uveitis, five asymptomatic HTLV-I carriers, 11 HTLV-I-negative patients with ocular sarcoidosis, and nine normal control subjects seronegative for HTLV-I. Six of the 11 patients with HTLV-I uveitis showed increased total cell counts, and T-lymphocytosis in BAL fluid. CD4+/CD8+ ratios of T-lymphocytes were decreased in three of these patients, and normal in three other patients. Such abnormalities of the lung were not found in asymptomatic HTLV-I carriers, and in normal control subjects. BAL findings in HTLV-I uveitis differed from those of patients with sarcoidosis in terms of the lymphocytic component. Interestingly, it was found that there was an increase of HTLV-I proviral deoxyribonucleic acid (DNA) load in peripheral blood mononuclear cells (PBMC) from seven patients with HTLV-I uveitis, and in the BAL cells from four patients with pulmonary involvement. These results provide further evidence in terms of HTLV-I tropism for the lung, and suggest that a systemic and local increase of HTLV-I proviral DNA load plays an important role in the pathogenesis of lymphocyte alveolitis in patients with HTLV-I uveitis.

Protein kinase C (PKC) has been shown to be involved in the mitogenic response and in oncogenic cell transformation in many experimental models. We analyzed the expression of PKC in both highly purified leukemic T cells freshly isolated from adult T-cell leukemia (ATL) patients and control T lymphocytes obtained from healthy volunteers. PKC activity was decreased in the ATL cells as compared with the control T cells. Cytosolic PKC activity in the ATL cells was remarkably decreased, whereas particulate membrane PKC activity was similar to the control level. The percentage of PKC activity in the particulate fraction was 34% in the ATL cells and 19% in the control cells. Regarding the altered subcellular localization of PKC activity, phorbol ester-induced translocation of cytosolic PKC was inhibited in some ATL cases. Similarly to the decrease in PKC activity, there was a decrease in the expression of the major PKC isozymes II(beta) and III(alpha) in ATL cells. These results suggest impaired regulation of PKC expression in ATL as well as in many experimental cancers.

A survey of 360 patients with various hematologic diseases revealed a high frequency of respiratory complications in patients with adult T-cell leukemia (ATL) compared to others. Among 29 patients with ATL, pulmonary complications were seen in 26 patients; leukemic pulmonary infiltration in 13, bleeding in 1, interstitial pneumonitis in 1, and pulmonary infection in 13. The incidence of Pneumocystis carinii and bacterial pneumonias were high despite adequate neutrophil count. Even in chronic and smoldering ATL, respiratory diseases were found in high frequency. Many of those were leukemic cell infiltration. In ten of 13 patients with pulmonary infiltration it occurred in the early stage and 6 of them were diagnosed as having "chronic lung disease" before the diagnosis of ATL. Its histology was accompanied by fibrosis in greater or lesser degree in almost all cases. Transbroncheal lung biopsy (TBLB) is of value in diagnosis (8 of 13 cases).

Surface phenotypes and genotypes of six T cell lines established from four patients with adult T cell leukemia (ATL) were compared with those of fresh ATL cells. The surface antigen densities of CD3 and T cell receptor (TCR) complex examined by OKT3 and WT-31 mAbs on fresh ATL cells were low. But three IL-2-dependent cell lines, SKT-2, SKT-5, and ATL-17-2, established from three patients expressed a high density of CD3-TCR complex on their surfaces. On the contrary, three other cell lines (SKT-1A, SKT-1B, and MMT-2), established from two other patients, expressed a low density of CD3-TCR complex. Genotypic analysis of TCR beta chain (T beta) gene and integration sites of the proviral genome of human T cell lymphotropic virus type 1 demonstrated that SKT-1A, SKT-1B, and MMT-2 were derived from the original leukemic clones. These apparent associations between a defect of expression of CD3-TCR complex and identical genotypes of fresh and cultured cells suggest that the defect of expression of CD3-TCR complex may play a key role for development of ATL.

Adenosine deaminase (ADA) was assayed in plasma from 14 patients with adult T-cell leukemia (ATL) (eight with acute ATL and six with smoldering or chronic ATL), 20 male family members (ten were anti-ATLA antibody positive and the other ten negative), and 25 normal individuals. ADA activity was uniformly higher in plasma from patients with ATL than normal controls. This enzyme activity significantly increased in acute ATL in comparison to smoldering or chronic ATL. In families of ATL patients, no statistical difference in ADA activity between the anti-ATLA antibody-positive group and -negative group could be discerned. The enzyme activity in a patient with acute ATL, after a bone-marrow transplant, rapidly increased as leukemic cells increased in peripheral blood. These findings indicate that the levels of ADA activities in plasma from ATL patients reflect the condition of this disease. Thus, measurement of this enzyme activity offers a further parameter to distinguish subtypes of ATL, and is of prognostic and therapeutic value.

Rearrangements of T cell receptor beta and gamma chain (T beta and T gamma) genes were analyzed by Southern blot method in samples from 30 patients with adult T cell leukemia (ATL) and 17 patients with non-ATL T cell neoplasms. The DNA probes used were the constant and joining region of T beta gene and the joining region of T gamma gene. Rearranged bands of T beta gene on one or both allelic chromosomes were detected in all neoplastic T cells, even those of smoldering ATL, in which only a small percentage of peripheral blood T cells were detected as leukemic. T gamma gene was rearranged in the cells of all but one patient, the exception being one ATL patient. In order to test whether any given variable region (V) of T beta gene was expressed in ATL cells, two functionally rearranged V beta sequences of ATL were compared with a V beta sequence from T cells acute lymphoblastic leukemia cells. No significant homologies were noted among the three deduced gene product amino acid sequences, confirming that T beta molecules of ATL cells contained no specific structures in common. The observed heterogeneity of T beta and T gamma gene rearrangements in ATL cells further supported these findings.

Chromosomes were studied in cells from 15 japanese patients with adult T-cell leukemia (ATL). Mitoses were obtained from unstimulated peripheral blood in 12 patients and a lymph node in one patient. In two other patients, mitotic cells were obtained solely from peripheral blood stimulated with phytohemagglutinin (PHA). Chromsomally abnormal cells were seen in 14 of the 15 patients. The abnormal cells had a modal number of chromosomes in near diploid range in 12 patients, and in near triploid and tetraploid range in the remaining 2 patients, respectively. Eight of the nine patients analyzed by Q-banding had clonal chromosome abnormalities. The most common abnormality was trisomy no.7 or 7q, which was seen in 5 cases and has been primarily observed in lymphoid neoplasms. A 14q+ marker chromosome was found in two patients and a Dq+ in one patient; loss of a sex chromosome was found in three patients. Most chromosomes were involved in gains, losses, or structural rearrangements, but abnormalities of no. 11, which have been frequently found in lymphoid malignancies, was not observed in our series. The significance of these chromosome abnormalities is discussed.

Serum concentrations of soluble interleukin 2 receptors (sIL 2R) were measured by an enzyme-linked immunosorbent assay (ELISA) in 30 patients with adult T cell leukemia (ATL), in 9 patients with other hematopoietic malignancies, and in 17 asymptomatic individuals seropositive for human T cell leukemia virus type I (HTLV-I). Sixty HTLV-I seronegative, age-matched controls showed a normal range of form 63.2 to 480.8 U/mL. All asymptomatic carriers of HTLV-I had sIL 2R in their sera within the normal range. sIL 2R in sera was not related to the anti-HTLV-I antibody titer. Eleven patients with acute ATL, a clinical phenotype with median survival rate of 4.4 months, had markedly elevated sIL 2R (11,100 to 99,000 U/mL), but eight patients with smoldering ATL had low sIL 2R values (less than 480.8 U/mL) comparable to controls. Eleven patients with chronic ATL had intermediate elevated levels of sIL 2R (480.8 to 37,300.0 U/mL). Serum levels of sIL 2R correlated with the number of ATL cells (r = 0.812) and CD25-positive cells (r = 0.725) circulating in the peripheral blood. Longitudinal studies performed in four patients with ATL showed significant correlation between serum concentration of sIL 2R and activity of the malignancy. These findings suggest that the level of sIL 2R in serum indicated tumor load and, possibly, prognosis.

Cells from eight patients with adult T cell leukemia (ATL) and from four patients with non-ATL were examined to see if the T3 antigen of these cells could be modulated in vitro. We found a low density of T3 antigen and the presence of Tac antigen on cells from all patients with ATL. The density of T3 antigen on non-ATL cells was normal, and Tac antigen was not detected. Modulation of T3 antigen and an increase in Tac antigen-positive cells occurred when cells from patients with T4 non-ATL were cultured with OKT3 monoclonal antibody (mAb). Those changes in T3 antigen density and the appearance of Tac antigen-bearing cells by OKT3 mAb were not so marked when ATL cells were used. But the modulation of T3 antigen and the increase in Tac antigen-bearing cells by OKT3 mAb were closely related in cells from six ATL patients. These findings suggest that T3 T cell antigen receptor complexes on ATL cells are not functionally "frozen" by leukemic changes and might be modulated in vivo. In addition, modulation of T3 surface antigen on ATL cells was not induced by cultivation with human T cell leukemia virus type I particles and envelope proteins obtained by gene technology.

The surface phenotype and the functional activities of leukemic cells from seven patients with adult T-cell leukemia (ATL) were studied using monoclonal antibodies OKT 3, 4 and 8, anti-Tac, and OKT 17. The latter defines the heterogeneity of the activated T4+ T cell subset. In all cases, ATL cells with the typical OKT3-T4+ T8- phenotype expressed OKT 17 antigen. In addition, in five out of the seven cases the fresh ATL cells possessed Tac antigen which is expressed on activated T cells in varying degree. After cultivation with PWM, most populations of ATL cells acquired Tac even in the cases expressing little antigen in uncultured preparations. However the PWM activated ATL cells did not lose OKT 17 antigen. Functional assays showed the suppressor activity of ATL cells on normal B cell differentiation in three out of six cases examined. These results suggest that ATL cells most probably arise from a particular subset characterized by OKT 17 antigen within the activated OKT4+ T cell subset.

We have explored the possible mechanisms for selective modulation by gangliosides of CD4 on human T lymphocytes and subsequent re-expression of CD4. Indirect immunofluorescence staining with anti-CD4 antibodies revealed newly internalized CD4 in ganglioside-treated cells after membrane permeabilization with 0.1% saponin. Cycloheximide and other metabolic inhibitors did not alter the modulation but inhibited significantly the re-expression of CD4. These results suggest both selective modulation of CD4 by a process of endocytosis and re-expression of CD4 through de novo protein synthesis.

Peripheral blood lymphocytes from seven patients with adult T-cell leukemia (ATL) were found to lack PHA-responsiveness. However, in most of the cases, minute but distinct proliferation could be induced and maintained by human spleen cell conditioned medium containing PHA or by a combination of PHA and conditioned medium of gibbon cell line, MLA-144 (MLA-144 CM). These results indicate that the lack of response to mitogens of ATL cells might be attributed not only to the failure of these cells to produce T-cell growth factor (TCGF) upon activation, but also to their poor responsiveness to TCGF. Furthermore, a direct proliferative response to mitogen-free MLA-144 CM was shown in two out of seven patients; these two patients experienced rapidly progressive clinical courses. This observation raises the possibility that TCGF promotes the growth of ATL cells in vivo, and is related to the clinical course of the disease.

Two siblings who developed adult T-cell leukemia (ATL) with unusual clinical courses are presented. The brother showed spontaneous remissions at the beginning stage of the disease of 6 years' duration, and the sister remains free of complaints for 6 years without chemotherapy. The patients and 2 of 12 healthy members of their family examined had serum antibodies against ATL-associated antigens (ATLA). The expression of ATLA was observed in the cultured lymphocytes from the patients and one of the family members.

As the first step in human immunodeficiency virus (HIV) infection, HIV binds to CD4 molecules on the surface of human T lymphocytes. Expression of CD4 by the cells is remarkably modulated by exogenously added gangliosides, which are normal components of the surface of animal cells. We report here that these physiological molecules also clearly inhibited HIV infection of lymphocytes in vitro in a dose-dependent manner through the selective modulation of CD4 from the cell surface. This raises the possibility of in vivo application of gangliosides as a new strategy for treating acquired immunodeficiency syndrome.

A monoclonal antibody termed anti-Tac antibody is reactive with activated and functionally mature human T cells, but not reactive with resting T cells or B cells. We found that the expression of Tac antigen on activated T cells was inhibited by the addition of anti-Tac antibody in the culture of T cells activated with Con A or alloantigen. In the mixed lymphocyte culture, the expression of Ia-like antigen on allo-activated T cells was also inhibited by anti-Tac antibody, although the antibody does not recognize Ia-like antigen. However, anti-Ia monoclonal antibody did not suppress the expression of either Tac or Ia-like antigen. In addition, Tac antigen expressed on activated T cells was modulated by anti-Tac antibody cultured with activated T cells at 37 degrees C for 48 hr. Antigenic modulation, which means a specific loss of Tac antigen from the cell surface of T cells, was detected by the indirect immunofluorescence method. Tac antigen was reexpressed on T cells after restimulation when the anti-Tac antibody was removed, whereas Ia-like antigen already expressed on allo-activated T cells was not modulated by anti-Tac antibody. These results suggest that Tac and Ia-like antigens are carried on different molecules, both of which are closely linked in expression on activated T cells. The expression of Tac antigen may be essential for the following expression of Ia-like antigen.

We report two patients with non-Hodgkin's lymphoma whose neoplastic cells had rearranged T cell gamma chain (T gamma) genes, and had the germ line DNA of T cell receptor beta chain (T beta) and immunoglobulin genes. Surface marker analysis of the neoplastic cells revealed that leukemic cells from one patient were derived from common thymocytes, while in the other patient the clonality and cell lineage could not be identified, probably due to the low percentage of neoplastic cells in the specimen. No phenotypic changes were observed after cultivation with phorbol myristate acetate, except for induction of Tac antigens on cells of one patient. Leukemic cells with only the T gamma gene rearrangement are thought to be precursor T cells that differentiate into mature T cells following T beta gene rearrangement. This suggests that such T cells with only the T gamma gene rearrangement exist among common thymocytes.

Adult T cell leukemia virus (HTLV or ATLV) proviral DNA integrated in the cellular DNA was examined by a modified Southern blotting method in the peripheral blood mononuclear cells and/or lymph node cells from 61 patients with adult T cell leukemia (ATL) and other hematologic diseases. Serum antibodies against ATL-associated antigens (ATLA) were also examined. The presence of human T cell leukemia virus (HTLV) proviral DNA was confirmed in all 20 patients with overt ATL and in 3 patients with T cell malignant lymphoma, who were seropositive but did not show clinical features characteristic of prototypic ATL. However, it was not detected in 6 antibody-positive healthy individuals and 8 seropositive patients with various hematologic disorders. Thus, the detection of proviral DNA by the method described here seems to be useful for the diagnosis of ATL in the endemic area and may provide a powerful tool for the classification of T cell malignancies.

Twenty-nine cases of adult T-cell leukemia were classified into four types according to the clinical features and course: smoldering, chronic, crisis, and acute. Only 2 of 14 patients with the acute type responded to therapy. The four types showed apparent differences in clinical features, complications, and prognosis, suggesting the need for different therapeutic regimens. For smoldering and chronic cases, no chemotherapy is recommended. However, in crisis and acute cases, aggressive chemotherapy is necessary, although the acute type cases showed extremely poor prognosis despite the most aggressive chemotherapy.

Sera obtained from patients with systemic lupus erythematosus (SLE) were tested for their reactivity to cell lines derived from cutaneous T-cell lymphoma (CTCL), or adult T cell leukaemia (ATL), and with other cell lines, by indirect immunofluorescence method. Approximately one half of SLE sera reacted with the surface antigens of HUT-102 cells, a cell line from CTCL, which constitutively expresses Tac antigen. The titre tended to be higher in the active than in the inactive stage. These positive sera also reacted with other neoplastic or normal T cell lines having Tac antigen. SLE sera reacting with HUT-102 surface antigens were further examined for their reactivities to Tac antigen, the putative IL-2 receptor, using HUT-102 or ATL-2. Pretreatment with anti-Tac monoclonal antibody partially blocked the reactivities to HUT-102 surface antigens in nine of 15 SLE sera tested. The binding of 125I-labelled anti-Tac monoclonal antibody was displaced by the addition of sera from six of 15 SLE patients. In addition, nine of the 15 SLE sera could inhibit the binding of 125I-labelled IL-2 to ATL-2 cells. These results suggested that some of SLE sera contained antibodies against the IL-2 receptor.

We studies the surface phenotype and the functional activities of leukemic cells from three patients with Japanese adult T-cell leukemic (ATL) using the panel of OK and anti-Tac monoclonal antibodies, which react with differentiation antigens and define functionally distinct T-cell subsets or activated and terminally differentiated T cells. The phenotype of ATL cells were determined to be OKT1+T3+T4+T10+T5-T8-Okla1-, although cells from two patients suppressed pokeweed mitogen (PWM) induced normal B-cell differentiation, and cells from all patients lacked helper activity in this system. In addition, after cultivation with PWM, ATL cells from all patients were reactive with anti-Tac monoclonal antibody, and cells from one patient were reactive with OKlal. These findings suggest that ATL cells arise from peripheral mature T-cell subsets and also suggest that the transition of surface phenotype of ATL cells to functionally mature and activated T cells occurs in culture.

Glycosphingolipids, which are functionally present on plasma membrane of mammalian cells, have a variety of functions in immune system such as surface markers of lymphocytes and mediators or modulators of the cells. Interestingly, gangliosides induced selective modulation of CD4, which is not only the subset marker of T-lymphocytes but also the receptor for human immunodeficiency virus. Here, we raised a process of endocytosis as a possible mechanism for the modulation of CD4. We also found that gangliosides inhibited HIV-infection in vitro.

Two siblings who developed adult T-cell leukemia (ATL) are presented. The patient and 7 of 26 healthy family members examined had the serum antibodies against ATL-associated antigens (ATLA). This family study shows that two main routes of transmission of human T-cell leukemia virus (HTLV) may be involved: one is the route from parents to children and the other is horizontal transmission among spouses, especially from husband to wife; the anti-ATLA-positive family is considered to be a high-risk group for ATL.

Adult T-cell leukemia-associated antigen (ATLA) and adult T-cell leukemia virus (ATLV) antigens were localized in the MT-2 cell system by the immunocolloidal gold method using 71 human sera having various anti-ATLA titers and rabbit anti-ATLV antisera. In the thin-section method with anti-ATLA-positive human sera and rabbit antisera, protein A-gold particles were preferentially observed on and around sectioned adult T-cell leukemia (ATL) virions located in pericellular aggregates and within the cytoplasmic vacuoles but nowhere else in a significant number. The number of gold particles per ATL virion was statistically well correlated with the anti-ATLA titers of human sera applied (p less than 0.005). The preembedding method showed that pericellular ATL virions were specifically tagged with protein A-gold, but the antigens in question were not expressed on the plasma membrane of MT-2 cells. The absence of ATLA and ATLV antigens on the plasma membrane constitutes a unique pathobiological feature of ATL and ATLV as compared with other retrovirus systems.

Trypstatin, a new cellular Kunitz-type protease inhibitor purified from rat mast cells, inhibited syncytium formation in human immunodeficiency virus type 1 (HIV-1)-infected CCRF-CEM and uninfected Molt-4 clone 8 at a concentration of 1 microM. Anti-rat tongue mast cell tryptase antibodies reacted with Molt-4 clone 8 cells, as determined by Western blot and by immunofluorescence. In addition, the antibody inhibited syncytium formation. These findings along with homologous sequences with trypstatin and a neutralizing epitope of gp120 of HIV-1 suggest that a tryptase-like cellular enzyme(s) is involved in HIV-1 infection.

The cell surface phenotypes of leukemic cells obtained from 30 patients with adult T-cell leukemia (ATL) were examined by means of a panel of OKT monoclonal antibodies and an anti-Tac monoclonal antibody. These leukemic cells were reactive with OKT1, OKT3, OKT4, OKT10, and OKT11 but not with OKT5, OKT6, OKT8 antibodies, suggesting that they were derived from peripheral mature cells included in the OKT4+ "helper/inducer" T-cell subset. Functionally, leukemic cells from none of the nine patients studied stimulated pokeweed mitogen (PWM)-driven immunoglobulin (Ig) synthesis by normal B cells. Suppressor cell activity, however, was found in 17 of 25 patients in PWM-induced Ig production. Fresh or cultured ATL cells from 22 of 23 patients tested expressed Tac antigen (interleukin-2 receptor) on the cell surface. The significance of Tac antigen on ATL cells is discussed in relation to the abnormal regulation of Tac antigen and leukemogenesis.

Sera from 154 hemophiliacs, including 132 with hemophilia A and 22 with hemophilia B, were examined for antibodies against human T cell lymphotropic virus type III (HTLV-III) and type I by strip radioimmunoassay based on the Western blotting technique. Sixty-two patients lived in Kyushu, a known endemic area of HTLV-I and 92 patients lived in Tokyo, a nonendemic area of HTLV-I. Results showed a prevalence of HTLV-III antibodies of 64.5% in Kyushu and of 57.6% in Tokyo. There were no significant differences between these two groups. Helper/suppressor (T4/T8) ratios of seropositive patients were 0.69 +/- 0.41 and those of seronegative patients were 1.05 +/- 0.56. Ratios of both groups were lower than those of normal healthy people (1.35 +/- 0.45). Our findings confirmed that hemophiliacs living in an HTLV-I endemic area and those living in a nonendemic area in Japan equally possessed antibodies to HTLV-III. Low T4/T8 ratios and increases of serum IgG and IgM levels were found even in seronegative hemophiliacs.

Age and sex distributions of monoclonal gammopathy were studied for 12,196 healthy controls and 2056 patients with various malignancies. The frequency of monoclonal component in adult T-cell leukemia (ATL) patients was found to be much higher than that in patients with other malignancies and in healthy controls. This suggested that the occurrence of ATL and monoclonal gammopathy is not coincidental. Three cases of ATL with monoclonal gammopathy are also reported.

Expression of interleukin 2 (IL-2) receptor (Tac antigen) on leukemic cells from 4 patients with acute lymphocytic leukemia (ALL) and 3 patients with blastic crisis of chronic myelogenous leukemia (CML-BC) was examined. Cells from 6 out of 7 patients did not carry immunoglobulins on their surfaces, but reacted with monoclonal antibodies (mAb) detecting B-cell related antigens such as B1, OKB2 and Leu12. Cells from two cases expressed Tac antigen immediately after cell separation. Phorbol 12-myristate 13-acetate (PMA) could induce Tac antigen in all cases. SDS-PAGE analysis of immunoprecipitates by anti-Tac mAb demonstrated that the molecular weight of Tac antigen on most of the leukemic cells was similar to that of Tac antigen present on Con A-stimulated normal lymphocytes. These leukemic cells poorly responded to exogenous recombinant IL-2. These findings suggest that IL-2 may interact with the immature and mature B cells, and play an important role in the differentiation of B lymphocytes.

Mitogen-induced T-lymphocyte proliferation is dependent on the presence of both interleukin 2 (IL-2) and transferrin, even though resting lymphocytes do not have receptors for either. Recently, it has been reported that IL-2 stimulates T-lymphocyte proliferation via IL-2 receptor by induction of transferrin receptor on these cells. Using leukemic T cells as a model of the monoclonal mature T cell, we examined those sequential steps of T-cell activation. Our studies revealed that transferrin receptors do not always appear after IL-2 receptor expression, IL-2 up-regulates the expression of IL-2 receptor but not of transferrin receptor, and IL-2 can initiate DNA synthesis without altering transferrin receptor expression. Thus, the sequential activation steps reported for normal T cells were not observed in the present study on leukemic T cells. These data suggest that there are other pathways to DNA synthesis in leukemic T cells and even in normal T cells.