Biochemical characterization of VLA-1 and VLA-2. Cell surface heterodimers on activated T cells

The very late antigen complexes VLA-1 and VLA-2 which appear on long-term activated human T cells have been characterized with respect to 1) subunit arrangement, 2) location of monoclonal antibody (MAb) binding sites, 3) carbohydrate content, and 4) protein homology. Cross-linking experiments showed that the VLA-1 complex is a heterodimer composed of an Mr 210,000 subunit (alpha 1) in acid-labile association with an Mr 130,000 subunit (beta). The VLA-2 complex is a heterodimer with an Mr 165,000 subunit (alpha 2) in base-labile association with the Mr 130,000 beta subunit. The subunits of VLA-1 (alpha 1 beta) and VLA-2 (alpha 2 beta) each appear to be arranged with 1:1 stoichiometry. The MAb A-1A5 has been shown to bind to an epitope on the common beta subunit, consistent with its recognition of both the VLA-1 and VLA-2 heterodimers. On the other hand, MAb TS2/7 bound to an epitope of the alpha 1 subunit, thus explaining the specific recognition of the VLA-1 heterodimer by TS2/7. Digestion of the alpha 1, alpha 2, and beta subunits with neuraminidase and with endoglycosidase F revealed that each subunit contains substantial sialic acid and N-linked carbohydrate. By one-dimensional peptide mapping, the alpha 1, alpha 2, and beta subunits were shown to be highly nonhomologous with respect to each other, although each subunit from different T cell sources appeared highly homologous if not identical.     

Accessory cell-T cell interactions involved in anti-CD3-induced T4 and T8 cell proliferation: analysis with monoclonal antibodies

The effect of monoclonal antibodies (Mab) directed at T cell and accessory cell (AC) surface molecules on OKT3-induced T4 and T8 cell proliferation was examined. Mab directed at nonpolymorphic class I (W6/32, MB40.5) and class II (L243) major histocompatibility complex (MHC)-encoded gene products, an epitope common to LFA-1, CR3, and the p150, 95 molecule (60.3), and a heterodimer present on monocytes (M phi) and activated T cells (4F2) inhibited M phi-supported OKT3-induced proliferation of both T4 and T8 cells. Moreover, an Mab directed at the CD4 molecule (66.1) inhibited OKT3-induced T4 but not T8 cell proliferation, whereas an Mab directed at the CD8 molecule (OKT8) inhibited T8 but not T4 cell responses. With the exception of 66.1, each inhibited OKT3-induced T cell proliferation when added as late as 15 hr after the initiation of culture. Inhibition could not be explained by competition for Fc receptors on the AC. A variety of other Mab including OKT11 and those directed at other HLA-DR and DQ determinants were not inhibitory. The inhibitory Mab were found to diminish T4 cell IL 2 production and IL 2 receptor expression. Consequently, IL 2 reversed some but not all of the Mab-mediated inhibition of T cell proliferation. In contrast to the effects noted with M phi-supported responses, 60.3 and 66.1 but neither L243 nor 4F2 inhibited OKT3-induced T4 cell proliferation supported by Ia- or IFN-gamma-treated Ia+ endothelial cells. None of the Mab tested inhibited T cell proliferation induced by the AC-independent stimuli OKT3 and phorbol myristate acetate (PMA) or calcium ionophore and PMA in the presence or absence of added AC. The data therefore suggest that the Mab inhibit OKT3-induced activation of T4 and T8 cells by preventing necessary interactions between AC and T cell surface proteins. Moreover, the results suggest that different arrays of interaction molecules are involved in OKT3-induced T cell proliferation depending on the nature of the AC and the responding T cell subset.     

Characterization of the cell surface heterodimer VLA-4 and related peptides

A monoclonal antibody (B-5G10) was produced which specifically recognizes the Mr 150,000/130,000 VLA-4 complex on the surface of human cells. Cross-linking studies indicated that the Mr 150,000 alpha 4 subunit of VLA-4 is in noncovalent 1:1 association with the Mr 130,000 VLA beta subunit. In the absence of cross-linking, the VLA-4 alpha 4 beta subunit complex was easily dissociated, especially in Nonidet P-40 detergent, or at elevated pH (above 8.0). Studies of dissociated subunits showed that B-5G10 recognizes an epitope on the Mr 150,000 alpha 4 subunit of VLA-4, whereas the beta subunit is immunologically identical to the Mr 130,000 beta subunit common to all VLA heterodimers. VLA-4 is widely distributed on hematopoietic cells, including thymocytes, peripheral blood lymphocytes, monocytes, activated T cells, T and B lymphoblastoid cell lines, and myeloid cell lines. However, VLA-4 is only weakly expressed on most adherent cell lines tested. Immunoprecipitates of VLA-4 often contain additional proteins of Mr 80,000 and Mr 70,000. These are probably derived from the Mr 150,000 alpha 4 subunit because: 1) they are both recognized by anti-alpha 4 sera, but not anti-beta sera; 2) the sum of their sizes is equal to the size of alpha 4; 3) they are selectively coexpressed with alpha 4 and not other VLA alpha subunits; 4) the Mr 80,000 protein has an identical NH2-terminal sequence to alpha 4; 5) like alpha 4, the Mr 70,000 and 80,000 peptides can variably associate with the VLA beta subunit; and 6) trypsin appears to cleave the Mr 150,000 alpha 4 subunit into products of Mr 70,000 and 80,000.     

Expression of surface lymphotoxin and tumor necrosis factor on activated T, B, and natural killer cells.

The expression of membrane-associated forms of lymphotoxin (LT) and TNF were examined on cell lines of T, B, and myeloid origin, IL-2 dependent T cell clones, and peripheral blood lymphocytes. Inducible and constitutive patterns of surface LT expression were found on T cells as exemplified by the II-23.D7, a CD4+T cell hybridoma, and HUT-78, a T cell lymphoma. Phorbol ester induced surface LT expression on Ramos, an EBV transformed B cell line, but at a slower rate of appearance when compared to the II-23.D7. Secretion of LT was rapidly inducible by phorbol ester in II-23.D7 and also in HUT-78 but with slower kinetics; surface LT expression continued in both lines after secretion had ceased. Low levels of membrane TNF were transiently induced on II-23.D7 and HUT-78, but none was observed on Ramos. Peripheral blood monocytes and some myeloid tumor lines did not express surface LT. Several T cell clones expressed surface LT after Ag-specific stimulation, and expression persisted several days. Stimulation through the TCR or by IL-2 rapidly induced surface LT on resting peripheral T cells and CD56+ NK cells; pokeweed mitogen activation induced expression on CD20+ B cells. Consistent with previous results, immunoprecipitation with anti-LT mAb showed that LT was complexed with a distinct 33 kDa glycoprotein (p33) on cells that expressed surface LT, whereas secreted LT was not associated with p33. Surface and secreted modes of LT expression by activated T, B, and NK cells suggests that LT can be utilized as either a localized or diffusible mediator in immune responses.     

Functional analysis of human T cell subsets defined by monoclonal antibodies. V. Suppressor cells within the activated OKT4+ population belong to a distinct subset

In the present report, we characterize a monoclonal antibody directed at a surface differentiation antigen on human T cells. The monoclonal antibody, OKT17, recognizes a cell surface antigen present on the majority of resting normal peripheral T cells. In contrast, OKT17 is unreactive with normal B cells, B cell lines, T cell lines, or SIg+ CLL. Interestingly, after activation, the antigen recognized by OKT17 is lost from a subset of OKT4+ cells. We took advantage of this finding to explore further the functional heterogeneity within activated OKT4+ cells. Evidence was obtained that the PWM-activated OKT4+ subset remaining after depletion of OKT17-reactive T cells (OKT4+ 17-) contains radiosensitive helperr cells but is devoid of suppressor cells. In contrast, the activated OKT4+ 17+ population contains potent radiosensitive suppressor cells as well as radioresistant helpe cells. Taken together, these studies suggest that the OKT17 monoclonal antibody can differentiate two functionally mature, activated OKT4+ human T cells: OKT4+ OKT17+ radiosensitive suppressor cells and OKT4+ 17- radiosensitive helper cells.     

Characterization of an antigen expressed on activated human T cells and platelets

We have identified a protein complex on the surface of activated human T cells and platelets. This Ag, detected by the murine mAb 1B3, is not expressed on resting human T cells or platelets or on other hematopoeitic cells. The majority of T cells express the Ag after stimulation with PHA, Con A, or allogeneic cells. Platelets express the Ag after activation with 1 U/ml thrombin. Immunoprecipitation of 125I-labeled activated T cells with antibody 1B3 shows a heterodimer of 180,000 and 155,000 Mr. An additional protein of 130,000 Mr is very faintly seen depending on the cell type. On platelets, the 180,000 Mr protein is the predominant protein immunoprecipitated under both nonreducing and reducing conditions. Antibody 1B3 may prove useful in identification of activated T cells and platelets as well as definition of specific mechanisms of T cell and platelet activation.     

Accessory cell independent proliferation of human T4 cells stimulated by immobilized monoclonal antibodies to CD3

The capacity of the monoclonal antibodies (Mab) 64.1 and OKT3 directed at CD3 molecules to induce T4 cell proliferation and interleukin 2 (IL 2) production was examined. Each was tested in soluble form or was immobilized by adhering it to the wells of plastic microtiter wells. Soluble anti-CD3 did not induce proliferation of accessory cell (AC)-depleted T4 cells. In contrast, immobilized anti-CD3 induced T4 cell IL 2 production and proliferation in the complete absence of AC. When T4 cells were stimulated with high density immobilized anti-CD3, responses did not require AC, IL 2, or Mab directed at the Tp44 molecule (9.3). In contrast, responses stimulated by lower densities of immobilized anti-CD3 were enhanced by IL 2, AC, and 9.3, and with even lower densities of immobilized anti-CD3 proliferation, required these additional signals. A variety of other immobilized Mab directed at T cell surface proteins including class I major histocompatibility complex encoded gene products, CD2, CD5, 4F2, and Tp44, did not induce proliferation even in the presence of IL 2. Anti-CD4 Mab (66.1) inhibited immobilized anti-CD3-stimulated T4 cell responses, with a greater degree of inhibition noted when lower densities of immobilized anti-CD3 were used to stimulate T4 cells. The data demonstrate that stimulation of T4 cells by anti-CD3 is completely AC independent when the antibody is immobilized onto a surface. Furthermore, the results indicate that maximal stimulation requires multiple interactions with anti-CD3 without internalization of the CD3 molecule. The observation that additional signals are required to support T4 cell proliferation when the density of immobilized anti-CD3 is diminished suggests that these are necessary only when insufficient interactions with the CD3 molecule have occurred to transmit a maximal activation signal to the cell. Finally, the results indicate that anti-CD4 provides a direct inhibitory signal to the T4 cell, the effect of which is inversely proportional to the intensity of the activation signal.     

Insulin receptor expression in the Burkitt lymphoma cells Daudi and Raji

The specific binding of insulin to either intact or Triton-solubilized Daudi cells (a Burkitt lymphoma cell line) was reduced by over 95% compared to that to control IM-9 lymphocytes due to a decrease in receptor number without a change in affinity. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography revealed that 125I-labeled Daudi cells had reduced amounts (approximately 1/20th) of immunoprecipitable binding (alpha) subunit [mol wt (Mr), 130,000] of the receptor and a relatively abundant 210,000 Mr form not seen in IM-9 cells. The transmembranous (beta) subunit (Mr, 90,000) of the receptor, although not detected by 125I surface labeling, could be phosphorylated and, together with the 210,000 Mr form, exhibited the same 2-fold stimulation of phosphorylation by insulin as that in IM-9 cells. Northern blot hybridization revealed a decrease in Daudi cells of all four major species of insulin receptor mRNA. The Raji cell, another Burkitt lymphoma cell line, also exhibited reduced protein and genetic expression of the insulin receptor, indicating that reduced insulin receptor expression may be representative of other Burkitt lymphoma cell lines.     

Role of the L3T4-antigen in T cell activation. II. Inhibition of T cell activation by monoclonal anti-L3T4 antibodies in the absence of accessory cells

We have used two monoclonal antibodies (Mab) to the L3T4 antigen to reexplore the role of this molecule in the process of T cell activation. Both Mab (Gk1.5 and 2B6) were capable of inhibiting Con A-induced IL 2 production by a number of antigen-specific T cell hybridomas in an assay system that was free of major histocompatibility complex (MHC) class II antigen-bearing cells. The inhibition produced by the anti-L3T4 Mab was specific, because other Mab to cell surface antigens expressed on the hybridomas were without inhibitory effects. These studies rule out the possibility that the mechanism of inhibition by anti-L3T4 in this model is mediated by blocking interaction of L3T4 with MHC class II products. Taken together, these results and those of other groups of investigators, are most compatible with a dual function for L3T4 in T cell activation. L3T4 might first interact with MHC class II molecules or other molecules on target or accessory cells; L3T4 would subsequently transmit a signal that would regulate the activation process. Mab to L3T4 might exert inhibitory effects at one or both of these steps.     

Inhibition of phosphatidylinositol 3'-kinase induces preferentially killing of PTEN-null T leukemias through AKT pathway

We examined the functional role of the phosphatidylinositol 3'-kinase pathway in the growth and survival of cell lines of T-cell origin. Pharmacological inhibition of PI3'-kinase using LY294002 resulted in apoptosis of acute lymphoblastic T-cell leukemia (T-ALL) cell lines including CEM, Jurkat, and MOLT-4. On the other hand, the cutaneous T-cell lymphoma cell line HUT-78 was found to be refractory to LY294002- inducible apoptosis. Sensitivity or resistance to pharmacological inhibitors of PI3'-kinase correlated with tumor suppressor PTEN gene expression, as sensitive T-ALL cells do not express PTEN and have high level of activated AKT, in contrast to HUT-78 cells. Our data demonstrate that inhibition of PI3'-kinase results in dephosphorylation of AKT and partial inhibition of Bcl-xL expression in T-ALL cells, but not in HUT-78 cells. Interestingly, HUT-78 cells were also found to express higher levels of Bcl-xL protein as compared to T-ALL cells. Inhibition of PI3'-kinase also induces release of cytochrome c from mitochondria and activation of caspase-3 and PARP in all T-ALL cell lines tested, but not in HUT-78 cells. Taken altogether, our data demonstrate that the PI3'-kinase/AKT pathway plays a major role in the growth and survival of PTEN-null T-ALL cells, and identify this cascade as promising target for therapeutic intervention in acute T-cell leukemias.     

Lateral diffusion measurements give evidence for association of the Tac peptide of the IL-2 receptor with the T27 peptide in the plasma membrane of HUT-102-B2 T cells

Fluorescence photobleaching recovery measurements show that the F1-IgG-labeled Tac peptide of the IL-2R can diffuse in the plane of the membrane of HUT-102-B2 T lymphocytes, with a mean diffusion coefficient of 2 to 3 x 10(-10) cm2s-1. Although only a fraction (mean 37%) of the Tac peptides is mobile on any given cell, lateral diffusion of the Tac peptide can be measured in 94% of cells examined. In contrast, the 95-kDa peptide, T27, is 90 to 100% immobilized in cells labeled with OKT27. Immobilization of T27 also affects the lateral diffusion of the Tac peptide, because the Tac peptide is immobile in more than 30% of cells pretreated with OKT27 and then labeled with anti-Tac IgG. The effect is specific for OKT27 to the extent that pretreatment with an anti-HLA mAb does not immobilize the Tac peptide. It appears, then, that Tac and T27 peptide not only are in proximity on HUT-102-B2 lymphocyte membranes but also interact physically in situ.     

Monoclonal antibodies, L-35 and L-36, define novel T cell activation antigens

Two novel T cell specific activation antigens were characterized and were defined by monoclonal antibodies developed against mitogen-stimulated human T cells. These antigens, designated as L-35 and L-36 were expressed on both the CD 4(Leu-3) and the CD 8(Leu-2) subsets of activated but not resting T cells. Moreover these antigens were not expressed on a number of T, B, and myeloid tumor cell lines. L-35 and L-36 were expressed on interleukin 2 (IL 2)-dependent cloned T cell lines, and were weakly expressed on the T cell tumor line, HSB-2. L-35 was expressed on granulocytes and a small subset of thymocytes. SDS-PAGE analysis of 125I-labeled lysates from phytohemagglutinin (PHA)-activated T cells demonstrated that L-35 existed as a complex of 32,000 and 97,000 dalton polypeptides under reducing and nonreducing conditions. Anti-L-36 immunoprecipitated a 90,000 dalton structure from PHA-activated cell lysates prepared with CHAPS detergent. When immunoprecipitates were analyzed from [35S]methionine labeled lysates, anti-L-35 precipitated only the 97,000 dalton component, suggesting that the 32,000 dalton subunit of L-35 complex was not synthesized by the activated cell population. Furthermore anti-L-35 did not immunoprecipitate a 32,000 dalton component from 125I-labeled lysates of anti-Leu-4 or Con A-activated cells, suggesting that the 32,000 dalton component of the L-35 complex may represent a subunit of PHA. The 32,000 dalton protein could not, however, be precipitated from cells incubated with PHA for less than 1 day. These results suggested that anti-L-35 recognizes a 97,000 dalton structure expressed on activated T cells, and that upon activation by PHA, becomes associated with a subunit of this mitogen.     

Immune deficiency in the X-linked lymphoproliferative syndrome. II. Immunoregulatory T cell defects

Surface phenotypic markers and the function of lymphocytes in patients affected with the X-linked lymphoproliferative syndrome (XLP) were studied. This syndrome is characterized by a defective response to infection with Epstein Barr virus (EBV). Normal numbers of B and T cells were detected with anti-Ig and monoclonal OKT3 antisera, respectively. T cell subset values, however, were persistently altered: cells reacting with OKT8 were significantly elevated in five of nine patients, accompanied by a slight decrease in the percentage of OKT4-positive cells, leading to abnormally low OKT4 to OKT8 ratios. One patient had a high OKT4 to OKT8 ratio due to low number of OKT8-positive cells. Lymphocytes from patients showed normal proliferation after stimulation with T and B cell mitogens. In contrast, Ig synthesis by lymphocytes after stimulation with B cell mitogens was markedly deficient: low or undetectable levels of one or all classes of Ig were detected, whereas cell lines established from EBV-infected B lymphocytes from patients produced normal quantities of Ig. These studies imply immune regulatory impairments in the patient with XLP.     

Defective suppressor cell function mediated by T8+ cell lines from patients with progressive multiple sclerosis

Activated suppressor cell function, induced with either concanavalin A or OKT3 and mediated by either unfractionated mononuclear cells or "panning" enriched T8+ cells, freshly isolated from peripheral blood, is reduced in patients with progressive multiple sclerosis (MS) as compared with control donors. In this study, we generated T8+ cell lines from the peripheral blood of these same patients and controls. Suppressor activity, mediated by T8+ cells exposed to OKT3 on days 1, 7, and 14 of culture and then treated with mitomycin C on day 16, was significantly reduced in the MS group (mean percent suppression 13% +/- 5) as compared with the control group (68% +/- 6, n = 8, p less than 0.001). No differences were noted in [3H]thymidine uptake by the OKT3-stimulated T8+ cell lines of MS and control groups. Mean percent suppression mediated by T4+ cell lines did not differ between MS and control groups (15% +/- 4, n = 3, vs 22% +/- 2, n = 4). These current data suggest that the previously observed defect in T8+ cell-mediated activated suppressor cell function in MS is a persistent one, favoring the postulate that the defect reflects intrinsic alterations in this cell population rather than a transient effect of serum factors on T8+ cell function.     

OKT4+ cytotoxic T cells can lyse targets via class I molecules and can be blocked by monoclonal antibody against T4 molecules

Human cytotoxic T lymphocytes (CTL) have been shown to recognize either class I or class II major histocompatibility (MHC) products. This recognition has been correlated with the expression of OKT antigens on the surface of the CTL. Thus, OKT4+ CTL have been shown to be reactive with class II products, whereas OKT8+ effectors recognize class I molecules. In this study, responder cells were separated according to their OKT4 or OKT8 cell surface phenotype on a fluorescence-activated cell sorter (FACS). The OKT4+ subsets were stimulated with an LCL mutant that did not express DR and MB/MT but did express SB and class I antigens. After 7 days in culture, the activated subsets were tested on a panel of class I matched or mismatched targets. The cytotoxicity observed could be correlated with the presence of matched class I antigens. In addition, monoclonal antibody (MCA) W6/32, directed at a monomorphic determinant on HLA-A and -B molecules, blocked lysis. Furthermore, six OKT4+ CTL clones were derived from the OKT4+ bulk cultures; three clones were found to be directed at class I molecules whereas the other three recognized class II determinants. The ability of these clones to lyse their relevant targets was blocked by OKT4 MCA, raising questions as to the role of the T4 molecule in antigen class-specific CTL recognition.     

Generation of lymphokine-activated killer activity in T cells. Possible regulatory circuits.

CD4+ and CD8+ T cells do not develop significant lymphokine-activated killer (LAK) activity when PBL are cultured with IL-2 or even when they are activated with a T cell stimulus such as OKT3 mAb. The possibility that a T cell regulatory mechanism prevents the development of LAK activity by CD4+ or CD8+ cells in OKT3 mAb and IL-2 cultures was tested by depleting CD8+ or CD4+ cells from PBL before stimulation with OKT3 and IL-2. Under these conditions, the remaining CD4+ and CD8+ cells were able to generate non-MHC-restricted lysis of NK-resistant tumor targets. Our data suggested that a regulatory signal was present in the culture to prevent the development of lytic function by T cells. T cells removed from the PBL cultures were, upon culture with IL-2, able to generate high LAK activity, suggesting that inhibition of the CD4+ or CD8+ T cell-mediated LAK activity was an active ongoing process, which blocked the lysis at the level of the activated cell and not the precursor cell. Mixing experiments demonstrated that the CD4+ or the CD8+ cells isolated from the PBL cultures were able to inhibit the development of lytic function in the CD4-depleted and CD8-depleted cultures. Transforming growth factor-beta (TGF-beta) has been shown to block LAK activity of NK cells in IL-2-stimulated cultures. When TGF-beta was added to CD4(+)- or CD8(+)-depleted cultures, it also inhibited LAK activity of T cells in a dose-dependent fashion, without interfering with T cell growth. Lytic activity returned to activated levels when TGF-beta was removed from the culture medium, thereby demonstrating the reversibility of TGF-beta inhibition.     

Monoclonal antibody OKT3-induced T cell proliferation: differential role of HLA class II determinants expressed by T cells and monocytes.

Monoclonal antibodies (MAb) to monomorphic determinants of HLA Class II antigens inhibit monocyte-dependent T cell proliferation induced by MAb OKT3 to a different extent, suggesting a differential regulatory role of the corresponding determinants in T cell proliferation. To elucidate the mechanism(s) underlying this pattern, the MAb CR10-343 and Q5/6 with high inhibitory effect and MAb CR11-462 and CR12-356 with low inhibitory effect were characterized. Cross-inhibition studies showed that the four MAb recognize distinct determinants. The determinants recognized by MAb CR10-343 and CR12-462 are spatially close. The determinants recognized by the four MAb appear to be functionally independent in MAb OKT3-induced T cell proliferation, since the inhibitory effect of the combination of MAb CR10-343 and Q5/6 and of the MAb CR11-462 and CR12-356 was additional but not synergistic. To compare the functional activity of HLA Class II determinants expressed by monocytes and by activated T cells in MAb OKT3-induced T cell proliferation, the effect of the four MAb on MAb OKT3-induced T cell proliferation in a monocyte-dependent and in a monocyte-free system was studied. Dose-response and proliferation kinetics studies showed that the four MAb display a similar inhibitory effect on MAb OKT3-induced T cell proliferation in a monocyte-free system. These results suggest fine differences in the role played by monocyte- and T cell-bound HLA Class II determinants in the regulation of MAb OKT3-induced T cell proliferation. This functional heterogeneity may enhance the flexibility of HLA Class II antigens to mediate cell-cell interactions involved in the proliferative response to a variety of mitogenic stimuli.     

Functional properties of T cells in patients with chronic T gamma lymphocytosis and chronic T cell neoplasia

The expanded T cell populations of 10 patients with either T gamma lymphocytosis (five patients) or proven chronic T cell malignancy (five patients) were analyzed with respect to functional activity in vitro, including proliferative responses to mitogens, cytotoxic activity (killer [K] and natural killer [NK] cell activity), and regulatory activity on pokeweed mitogen- (PWM) induced immunoglobulin (Ig) synthesis (help and suppression) in comparison with marker phenotypes. In each of the five patients with T gamma lymphocytosis, only one out of three functionally distinct cell types was found: T gamma-K cells, T gamma-S cells, or T gamma-NK/K cells, which mediated K-cell activity, suppressive activity, and both NK and K cell activity, respectively. An expanded T gamma-K cell population was demonstrated in three patients with neutropenia with or without recurrent infections. T gamma-S cells were found in a patient with severe hypogammaglobulinemia, and T gamma-NK/K cells in one patient with asymptomatic lymphocytosis. T gamma-K and T gamma-S cells had a similar surface-marker profile (E+ or E-, Fc gamma+, OKT1-3+4-8+I1-M1-), whereas that of T gamma-NK/K cells was different (E+, Fc gamma+, OKT1-3-4-8-I1+M1+). Longitudinal studies of three untreated patients with T gamma-K lymphocytosis showed that the abnormalities were persistent but not progressive. In contrast, five patients with chronic T cell malignancy (two with T-CLL, two with cutaneous T cell lymphoma [CTCL], and one with T-PLL) all had progressive disease. The neoplastic cells in these cases were E+, Fc gamma-OKT1+4+6- with variable expression of the OKT3 and OKT8 markers. The only functional activity observed in these cells was suppressive activity by OKT3-4+8- cells from a patient with CTCL.     

Immortalization of BGDF (BCGF II)- and BCDF-producing T cells by human T cell leukemia virus (HTLV) and characterization of human BGDF (BCGF II)

Human peripheral T cells were transformed by human T cell leukemia virus (HTLV), and T cell lines producing BGDF (BCGF II) and BCDF were established. Among these cell lines, a cell line, TCL-Na1, secreted the highest level of both BGDF and BCDF, and the amount of BCDF secreted by TCL-Na1 cells was 900-fold more than that produced by PHA-stimulated T cells. Within the limits of our examination, none of the HTLV-transformed T cell lines produced IL 2 or BSF-p1 (BCGF I). BCDF produced by TCL-Na1 cells had a m.w. of 35,000 and a pI value of 5.5, being separated from BGDF, which was eluted in the fractions corresponding to m.w. of more than 60,000 and pI values of 5 to 6. BGDF induced both proliferation and IgM secretion in a mouse leukemic B cell line, BCL1, and these activities were not separated by either isoelectric focusing or gel filtration in the presence or absence of 0.1% Triton X-100, suggesting that the molecule designated BGDF exerted both growth and differentiation activities. BGDF acted on normal mouse B cells to induce proliferation as well as IgM secretion. The target cells of BGDF were in vivo activated B blast cells. BGDF acted on DXS-activated murine B cells to induce both proliferation and IgM secretion but not anti-Ig-activated B cells, indicating that BGDF and BSF-p1 were different molecules.