Murine terminal deoxynucleotidyl transferase: cellular distribution and response to cortisone.

The mouse thymus contains two forms of terminal deoxynucleotidyl transferase (TdT) which are distinguishable by the salt concentration necessary to elute them from a phosphocellulose column, by their distrubtion among the thymocyte subpopulations, and by their sensitivity to cortisone treatment. In the whole thymus the later eluting peak (peak II) is the predominant one with about 3-10% of the total activity appearing in peak I. Both peak I and peak II activities are most sensitively assayed by the polymerization of dGMP onto an oligo(dA) primer. The minor population of thymocytes which is less dense and cortisone-resistant contains a higher specific activity of peak I TdT. The majority of TdT activity is, however, found in the major population of thymocytes which occurs in the center region of a bovine serum albumin gradient and is cortisone-sensitive. A very low level of an activity indistinguishable from peak II TdT activity is also detected in the mouse bone marrow. Other tissues, such as spleen, liver, heart, and brain lack detectable amounts of TdT activity.

Functional analysis of human T cell subsets defined by monoclonal antibodies. IV. Induction of suppressor cells within the OKT4+ population.

In this report, we explored the functional heterogeneity within the OKT4+ subset of human T cells. Evidence was obtained that although in vitro pokeweed mitogen-activated OKT4+ cells can function as radioresistant helper cells, these activated OKT4+ cells could also exert potent feedback suppression. Despite the induction of suppressor cells after pokeweed mitogen activation, the OKT4+ population maintains its original OKT3+, OKT4+, nd OKT8- surface phenotype. The suppressor cells contained within the activated OKT4+ population were found to be radiosensitive. Importantly, the suppression mediated by activated OKT4+ cells required the presence of radiosensitive cells contained within the resting OKT4+ population. Taken together, these results suggest that the OKT4+ subset of human T cells contains cells that can be activated to differentiate into suppressor cells independent of OKT8+ cells.

Ia determinants on human T-cell subsets defined by monoclonal antibody. Activation stimuli required for expression.

The nature of Ia antigens which appear on human T cells after activation and the stimuli required for their expression was examined utilizing a monoclonal antibody reactive with the Ia antigen framework. T cells were purified using monoclonal antibodies directed either at the entire T-cell population (OKT3) or the T-cell inducer subset (OKT4). By indirect immunofluorescence, it was shown that the human T-cell population contains no detectable Ia+ cells in the resting state. In contrast, in excess of 60% of the T-cell population expresses Ia antigen after alloactivation in the mixed lymphocyte culture. Moreover, these Ia antigens are expressed within both the OKT4+ and OKT4- subsets. Similarly, phytohemagglutinin and concanavalin A induced approximately 20% of peripheral T cells to express Ia antigen and the expression of these antigens is not restricted to either OKT4 subset. In contrast, only the inducer T-cell population which proliferates maximally to soluble antigen expresses Ia antigens after activation by tetanus toxoid. Thus, the expression of human Ia antigens on unique T-cell subsets depends upon the activation stimuli utilized and ability of the individual subset to respond to a given stimulus. Additional studies indicated that Ia antigens appear on previously Ia- T cells after activation and do not result from clonal expansion of a small subset of Ia+ T cells.

The relationship between T lymphocyte subsets and Ia-like antigen positive nonlymphoid cells in early stages of cutaneous T cell lymphoma.

Immunofluorescence studies were carried out in cutaneous T cell lymphoma (mycosis fungoides) in order to analyse the microanatomical relationship of the different T lymphocyte subsets (inducer and suppressor/cytotoxic cell populations) to large nonlymphoid Langerhans-type and so-called "indeterminate" or interdigitating cells. The conventional and mouse (monoclonal) antibodies were used in various combinations using fluorescein and rhodamine labeled second layers. In 5 of the 7 cases studied the dermal infiltrate consisted of numerous T (HuTLA+) lymphocytes, 80-90% of which expressed the inducer phenotype (HuTLA+,OKT4+). Most of these cells formed close contact with large cells exhibiting large amounts of Ia-like antigens. These cells corresponded to the interdigitating and indeterminate cells in the sections. By contrast, only small numbers (10-20%) of T cells of suppressor/cytotoxic type (HuTLA+,OKT8+) were seen. These did not show a close affinity to the Ia-like antigen positive nonlymphoid component but appeared to have a predilection for the epidermis. Epidermal Langerhans cells, also strongly Ia-like antigen positive, were further defined by 2 monoclonal antibodies reacting with a cortical thymocyte antigen HTA-1. Although Langerhans cells are probably related to the Ia-like antigen positive dermal cells only a few of the abundant latter population were HTA-1+. In the remaining 2 cases, larger populations of OKT8+ (suppressor/cytotoxic) cells were seen and could be heralding a particularly benign course. These observations indicate a close functional relationship between the lymphoid and Ia-like antigen positive dermal cells during the pre-malignant phase of cutaneous T cell lymphoma.

Immunoelectron microscopic identification of Langerhans cells using a new antigenic marker.

The specificity of a monoclonal antibody (OKT6) for epidermal Langerhans cells was examined by immunoelectron microscopy. Peroxidase-labeled OKT6 bound to 1-5% of suspended human epidermal cells, as determined by light microscopy. Electron microscopic examination of peroxidase-labeled cells revealed that all Birbeck granule-containing Langerhans cells bound OKT6. In addition, a small population of indeterminate cells, lacking the Birbeck granule, was also labeled with OKT6. The ultrastructural studies confirm the specificity of OKT6 for Langerhans cells and suggest that the indeterminate cell represents a related cell population.

Terminal deoxynucleotidyl transferase in the diagnosis of leukemia and malignant lymphoma.

Neoplastic cells from 253 patients with leukemia and 46 patients with malignant lymphoma were studied for the presence of terminal deoxynucleotidyl transferase (TdT) by biochemical and fluorescent antibody technics. TdT was detected in circulating blast cells from 73 of 77 patients with acute lymphoblastic leukemia, 24 of 72 patients with chronic myelogenous leukemia examined during the blastic phase of the disorder and in cell suspensions of lymph nodes from nine of nine patients with diffuse lymphoblastic lymphoma. Blast cells from six of 10 patients with acute undifferentiated leukemia were TdT positive, but the enzyme was found in only two of 55 patients with acute myeloblastic leukemia. TdT was not detected in other lymphocytic or granulocytic leukemias or in other types of malignant lymphomas. The fluorescent antibody assay for TdT permits rapid and specific identification of the enzyme in single cells. The TdT assay is clinically useful in confirming the diagnosis of acute lymphoblastic leukemia, evaluating patients with blastic chronic myelogenous leukemia, and distinguishing patients with lymphoblastic lymphoma, whose natural history includes rapid extranodal dissemination, from patients with other poorly differentiated malignant lymphomas.

A critical analysis of serum and urine interleukin-2 receptor assays in renal allograft recipients.

A component of the interleukin 2 receptor (IL-2R) is released in soluble form during T cell activation and can be detected in the blood during acute renal allograft rejection. This study evaluates the diagnostic utility of a sandwich enzyme immunoassay test for serum and urine IL-2R in renal allograft recipients. A rise in serum IL-2R during the week prior to the clinical diagnosis of rejection correlated better with rejection than did isolated serum IL-2R levels or urine values. For the diagnosis of acute rejection, a rise in serum IL-2R (sensitivity 73%, specificity 87%) was comparable in overall test performance to a rise in serum creatinine (sensitivity 70%, specificity 84%). Overall, the two tests had equivalent receiver operating characteristic curves. Because the etiology of false positives in creatinine and IL-2R assays differed (primarily cyclosporine toxicity and infection, respectively), the predictive value of the combined tests was superior to either alone.

Antigenic polymorphism of the T4 differentiation antigen expressed on human T helper/inducer lymphocytes.

The human TH lymphocyte population has been established to express a differentiation antigen (T4) which appears to function in cellular collaboration and T cell recognition of Class II MHC alloantigens. Because we observed altered immunofluorescence staining of the TH cells of some individuals using the OKT4 mAb, a systematic investigation on both the epitopic structure of the T4 glycoprotein molecule and possible polymorphism of these epitopes was undertaken. From competitive blocking assays using eight murine anti-T4 mAbs coupled with quantitative flow cytometry, at least five and possibly seven different epitopes can be recognized on the T4 molecule. Population studies showed some individuals had a reduced phenotypic expression of the OKT4 reactive determinant to one-half that of normal and others completely lacked this epitope. The OKT4 reactive epitope variations are common but have so far been racially restricted to American Blacks and do not appear related to the stage of TH cell differentiation, any identifiable immune abnormality in vitro, or a definable disease process. The OKT4 epitope cannot be unmasked by neuraminidase treatment or T cell stimulation with lectins, soluble antigens, or allogeneic lymphocytes. Coupled with a family study, the alterations in OKT4 phenotype are best explained by autosomal, codominant expression of the T4 gene product. The significance of this polymorphism on TH cell function remains unclear.

Monoclonal antibodies which distinguish between human NK cells and cytotoxic T lymphocytes.

Although it is widely accepted that T cells have a major role in specific tumour immunity, there is now much evidence that natural killer (NK) cells, which exist in many species and spontaneously lyse certain tumour cells in vitro, provide early resistance against tumour growth. Human NK-cell activity can be augmented in vitro by interferon and its inducers, including polyinosinic:polycytidylic acid (poly I:C); furthermore, NK-like activity is generated in mixed leukocyte cultures (MLCs) as is specific cytotoxic T-cell (Tc) activity. When effector cells generated in human MLCs lyse allogeneic or autologous virus-transformed or tumour cells, it has been difficult to evaluate the relative contributions of Tc and NK-like cells to the lysis because the latter, like T cells, can form rosettes with sheep erythrocytes and react with xenogeneic anti-human thymocyte serum. We report here that monoclonal antibodies against human mononuclear cell subpopulations can distinguish Tc from NK and NK-like cells. OKT3 or OKT8 monoclonal antibodies (reactive with virtually all or a subset of T cells, respectively) with complement (C') ablate MLC-generated Tc activity against allogeneic normal cells but do not decrease lysis of HLA-negative, NK-sensitive K562 leukaemia cells by NK, poly I:C-activated NK or MLC-activated NK-like cells. In contrast, OKM1 monoclonal antibody (reactive with a low proportion of non-adherent mononuclear cells as well as macrophages) with C' causes marked diminution of NK and poly I:C-activated NK-cell activity.

Functional and developmental compartments of human T lymphocytes.

Hybridoma technology has made it possible to prepare a range of antibodies which define developmental and functional compartments of the T lymphocyte lineage in man. The feasibility of achieving this aim, and some immediate clinical applications, are illustrated in this report on seven monoclonal antibodies from seven selected hybridoma clones, which are shown to define subclasses of human T cells according to their immune function and developmental rank.

Sensitization of lymphocytes against pooled allogeneic cells. II. Characterization of effector cells cytotoxic for autologous lymphoblastoid cell lines.

Stimulation of human lymphocytes in mixed leukocyte culture (MLC) with x-irradiated pooled allogeneic normal cells (poolx) was previously shown to result in generation of effector cells cytotoxic for autologous Epstein-Barr virus- (EBV) transformed lymphoblastoid cell lines (LCL). This study was undertaken to determine whether lysis of the autologous EBV- transformed LCL cells by pool-stimulated cells is mediated by cytotoxic Tc lymphocytes (Tc) or natural killer- (NK) like cells, both of which are generated in MLC. In the first series of experiments, proliferating cells were eliminated by treatment of pool-stimulated cells with 5 X 10(-5) M 5-bromodeoxyuridine (BUdR) and light. The remaining cells failed to lyse allogeneic normal lymphocytes and autologous LCL cells, whereas cytotoxicity against NK-sensitive K562 leukemia cells was retained. In the second series of experiments, pool-stimulated effector cells were treated with monoclonal anti-human Tc cell antibodies, OKT3 or OKT8, and complement (C). The cells recovered after antibody and C treatment were diminished in their ability to lyse allogeneic normal lymphocytes as well as autologous LCL cells, whereas their cytotoxicity against K562 leukemia cells was unaffected. These combined results provide strong evidence that lysis of autologous LCL cells by lymphocytes stimulated with pooled allogeneic normal cells is mediated by Tc rather than NK-like cells.

Terminal deoxynucleotidyltransferase. Serological studies and radioimmunoassay.

Mouse antisera against calf terminal deoxynucleotidyltransferase (terminal transferase) have been prepared. The sera have been used to characterize terminal transferase both by studying inhibition of enzyme activity and by developing a competition radioimmunoassay using highly purified 125I-labeled terminal transferase. By either assay, anti-terminal transferase serum did not cross-react significantly with calf DNA polymerases alpha and beta, Escherichia coli DNA polymerase I, or the reverse transcriptase of Moloney mouse leukemia virus. The calf terminal transferase did, however, share cross-reactive but not identical determinants with human and murine terminal transferase. The radioimmunoassay could detect as little as 2 ng of terminal transferase/mg of soluble protein in a tissue extract. Thymocytes were found to contain 280 ng of terminal transferase/mg of cell protein or about 1 X 10(5) molecules/cell; bone marrow had about 1% of the level of enzyme found in thymus. Extracts of spleen, peripheral white blood cells, lymph nodes, liver, muscle, and kidney all lacked detectable antigenicity of terminal transferase. These data indicate that terminal transferase is a tissue-specific enzyme and is not related to other DNA polymerases.

Hepatitis B virus-reactive human T lymphocyte clones: antigen specificity and helper function for antibody synthesis.

To study immunity to hepatitis B surface antigen (HBsAg) at the cellular level, lymphocytes were obtained from the peripheral blood of hepatitis B vaccine recipients and were examined for various immune responses to HBsAg in vitro. The peripheral blood mononuclear cells (PBM) from most of the vaccinees did not proliferate to a great extent to HBsAg in vitro. However, HBsAg-reactive lymphocyte lines and clones were obtained from some of these individuals if the PBM were stimulated in vitro with HBsAg and were maintained in the presence of T cell growth supplement. Most of the HBsAg-reactive T cell clones obtained were found to be antigen-specific and some of them provided help in the production of anti-HBsAg antibodies by a cell population enriched for HBsAg-binding cells. These results indicate that HBsAg-specific T and B cells exist in the circulation of hepatitis B vaccine recipients, although they are at limiting concentrations for the in vitro cell proliferation and antibody production assays.

Chemical composition and serological analysis of the cell wall of Peptostreptococcus.

Bahn, Arthur N. (Northwestern University, Chicago, Ill.), Patrick C. Y. Kung, and James A. Hayashi. Chemical composition and serological analysis of the cell wall of Peptostreptococcus. J. Bacteriol. 91:1672-1676. 1966.-Chemical and serological analyses were made of the cell wall of Peptostreptococcus to characterize taxonomically this genus of anaerobic streptococci. Cell wall hydrolysates of P. putridus strains 06 and 85, P. intermedius strains 11 and 87, and P. elsdenii strain B-159 were prepared, and the cell wall sugars were measured quantitatively by paper chromatography. Strain 85 contained only glucose, whereas strain 06 contained 93% glucose and 7% mannose. Strain 87 contained only rhamnose, and strain 11 contained approximately equal amounts of glucose and rhamnose. Strain B-159 differed from all the other strains in having a low (3.1%) content of total carbohydrate, consisting of rhamnose, galactose, and glucose. Quantitative amino acid analyses showed that the major amino compounds present in the cell wall were glutamic and aspartic acids, alanine, lysine, muramic acid, glucosamine, and galactosamine. Strains 06 and 85 possessed this complement of amino compounds, but strains 11 and 87 had relatively little aspartic acid. Strain B-159 was markedly different in having a high content of glycine and diaminopimelic acid, with only traces of lysine; it was the only strain in which teichoic acid was found. Serological analyses were made with the use of cell wall extracts as antigenic material and with homologous antisera, as well as streptococcal group antisera for groups A through S. The only strong agglutination was obtained between strain 87 antigen and group C antisera; weak agglutination was obtained with 87 against N, O, and K, and between strain 11 and groups E and F. All other antisera gave negative reactions. It is concluded that strain B-159 does not belong to the genus Peptostreptococcus, that strains 06 and 85 are members of P. putridus, and that strains 11 and 87 may be members of two different genera.

Isolation and characterization of murine monoclonal antibodies specific for gram-negative bacterial lipopolysaccharide: association of cross-genus reactivity with lipid A specificity.

Somatic cell hybrids secreting monoclonal antibodies against the core-glycolipid portion of enterobacterial endotoxin were derived from mice immunized with Escherichia coli J5 or Salmonella minnesota R595 heat-killed organisms or lipopolysaccharide (LPS). Eight antibodies were selected for their ability to cross-react with several members of a panel of gram-negative bacterial antigens in a radioimmunoassay. This panel represented five genera and two families of organisms: E. coli O111:B4, E. coli O55:B5, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella minnesota, and Serratia marcescens. The binding sites for six of the antibodies were unequivocally localized within the lipid A moiety of the endotoxin molecule by using the radioimmunoassay on LPS and free lipid A. The anti-lipid A antibodies were further characterized for their ability to interact with LPS variants by using a sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunostaining procedure. The monoclonal antibodies bound almost exclusively to the low-molecular-weight species of LPS on the polyacrylamide gel. These components corresponded to LPS isolated from rough strains of organisms (strains which lack O-specific carbohydrate). These results suggested that the cross-reactive component of antisera raised against rough mutants of gram-negative bacteria contain antibodies of lipid A specificity. Moreover, the determinant within the lipid A moiety of LPS may have been accessible to the monoclonal antibodies only in those endotoxin molecules on the outer membrane surface which lack the O-specific carbohydrate.

Use of monoclonal antibodies as sensitive and specific probes for biologically active human gamma-interferon.

Mouse monoclonal antibodies B1 and B3 are specific for natural and Escherichia coli-derived recombinant human gamma-interferon (IFN-gamma). The two antibodies recognize different epitopes of the IFN-gamma molecule and do not compete with each other's binding. We have used these two antibodies to construct a solid-phase, sandwich immunoradiometric assay for human IFN-gamma. Purified antibody B1 was coated on polystyrene beads (0.64 cm in diameter) and used as the solid-phase immunoadsorbent and antibody B3 was labeled with 125I and used as tracer. This assay can be completed in about 4 hr and is capable of detecting IFN-gamma levels in human serum or tissue culture fluids as low as 0.1 NIH reference unit/ml. Recombinant human IFN-gamma derived from E. coli was detectable at a concentration of 0.02 ng/ml. The assay appears to be specific for the biologically active forms of IFN-gamma, since after exposure to pH 2, 37 degrees C, or 56 degrees C, biological activity and reactivity in the immunoradiometric assay decreased in parallel. The immunoradiometric assay can be employed for the analysis of the structural characteristics of the human IFN-gamma molecule.