Anomalous leukopoiesis in two patients with Crohn's disease.

Crohn's disease is a major form of chronic inflammatory bowel disease in the western world. The molecular genetic basis of Crohn's disease is unknown. In this study, we present evidence for anomalous leukopoiesis-namely, the generation of a leukocyte subset characterized by aberrant expression of gammadelta T cell receptor (gammadeltaTCR) with or without CD19 on a myeloid background-in two patients with Crohn's disease.

Engraftment of human T-cell acute lymphoblastic leukemia in immunodeficient NOD/SCID mice which have been preconditioned by injection of human cord blood.

Childhood T-cell acute lymphoblastic leukemia (T-ALL) is one of the most common childhood cancers. Study of leukemia biology, as well as preclinical testing of potential therapeutic regimens directed at T-ALL, has been impeded by the lack of an efficient in vivo model of primary leukemia. We have reported elsewhere some observations that human cord blood conditioned medium enhances leukemia colony formation in vitro and preconditioning of sublethally irradiated nonobese diabetic/ severe combined immunodeficient (NOD/SCID) mice with cord blood mononuclear cells (MNCs) facilitates the subsequent engraftment of primary T-ALL cells in these mice.

Human cord blood conditioned medium enhances leukemia colony formation in vitro.

Childhood T-cell acute lymphoblastic leukemia (T-ALL) is one of the most common childhood cancers. Recently, we observed that pre-conditioning sub-lethally irradiated immunodeficient mice with human cord blood mononuclear cells facilitates in these mice high level engraftment of primary T-ALL cells obtained from patients. Here we report that human cord blood cells secrete a factor(s) which markedly enhances in vitro both colony number and burst size of the T-ALL clonogenic progenitors from patients.

Functional and biochemical characterization of a novel human macrophage-derived negative regulator of haematopoiesis.

It is believed that haematopoiesis is regulated by both positive and negative signals derived from the marrow microenvironment, which includes macrophages. The identity and mechanism of action of the proteins mediating negative regulation is an area of active investigation. We report here the identification and initial characterization of a novel suppressor of early haematopoietic progenitors, designated NRH (for Negative Regulator of Haematopoiesis), isolated from the recently established human macrophage line 2MAC.

Cytokine modulatable signalling through macrophage HLA class II. 1. IFN-gamma upregulates the efficiency of Ca2+ mobilization in response to ligation of macrophage HLA-DP.

The human macrophage line 2MAC, established recently from peripheral blood, expresses a number of lineage-specific markers as well as a broad array of intercellular adhesion molecules, including high levels of HLA class I and class II. We have presented evidence elsewhere that 2MAC can be productively applied to the study of signal transduction through macrophage HLA class II. Namely, we showed that ligation of 2MAC HLA class II, but not HLA class I, by monoclonal antibody (mAb) elicits an increase in free cytoplasmic Ca2+ concentration [Ca2+]i.

Characterization of a new human macrophage cell line 2MAC. 1. Expression of functional macrophage CD16 (Fc gammaRIIIA/gamma) and tissue factor induction on ligation of HLA-DR.

A human macrophage-like line, designated 2MAC, has been established from peripheral blood. 2MAC expresses a number of lineage-specific markers as well as a broad array of intercellular adhesion molecules. In particular, 2MAC expresses CD16/Fc gammaRIII, the low-affinity Fc receptor for IgG, as well as high levels of HLA class I and class II.

Phenotypic and functional characterization of a new human macrophage cell line K1m demonstrating immunophagocytic activity and signalling through HLA class II.

A human macrophage line, designated K1m, has been established from peripheral blood. K1m expresses a number of lineage-specific markers as well as a broad array of intercellular adhesion molecules. In particular, K1m expresses high levels of human leucocyte antigen (HLA) class I and class II.

Characterization of an anti-Ly-6 monoclonal antibody which defines and activates cytolytic T lymphocytes.

HK1.4 mAb was identified based on its ability to stimulate proliferation of cloned murine CTL. Within the lymphoid lineage, mAb HK1.

Rearrangement and expression of T-cell antigen receptor genes in human T-lymphocyte tumor lines and normal human T-cell clones: evidence for allelic exclusion of Ti beta gene expression and preferential use of a J beta 2 gene segment.

The gene encoding the beta chain of the human T-cell receptor for antigen is composed of variable (V), diversity (D), joining (J), and constant (C) gene segments which undergo specific rearrangements during T-lymphocyte ontogeny. Southern blot analyses of seven human T-cell tumor lines and normal human T-lymphocyte clones revealed that most of these T-cell lines rearrange their Ti beta genes differently. The T-cell tumor line HPB-MLT rearranges and transcribes both of its Ti beta genes.

Isolation of complementary DNA clones encoding the human lymphocyte glycoprotein T1/Leu-1.

The T1/Leu-1/CD5 molecule, a human T-cell surface glycoprotein of relative molecular mass (Mr) 67,000, has been implicated in the proliferative response of activated T cells and in T-cell helper function. A similar involvement in T-cell proliferation has been reported for Ly-1, the murine homologue of T1. Here we report the complete amino-acid sequence of the T1 precursor molecule deduced from complementary DNA clones.

Identification of a putative second T-cell receptor.

Framework monoclonal antibodies have identified a population of human lymphocytes that express the T3 glycoprotein but not the T-cell receptor (TCR) alpha- and beta-subunits. Chemical crosslinking experiments reveal that these lymphocytes express novel T3-associated polypeptides, one of which appears to be the product of the T gamma gene. The other polypeptide may represent a fourth TCR subunit, designated T delta.

Human T-cell gamma genes contain N segments and have marked junctional variability.

The gamma-chain genes are encoded by immunoglobulin-like gene segments in germline DNA which rearrange during the somatic development of T cells to form an active gene. The protein produced by these genes has not been identified and the diversity of the proteins that the genes can express has not been determined. We expect that the diversity of expressed gamma-chains is produced by the same three mechanisms that produce diversity of other immunoglobulin-like genes: (1) germline variable (V) and joining (J) region repertoires; (2) somatic mutation; and (3) junctional diversity.

Cloning and sequence analysis of complementary DNA encoding an aberrantly rearranged human T-cell gamma chain.

Complementary DNA (cDNA) encoding a human T-cell gamma chain has been cloned and sequenced. At the junction of the variable and joining regions, there is an apparent deletion of two nucleotides in the human cDNA sequence relative to the murine gamma-chain cDNA sequence, resulting simultaneously in the generation of an in-frame stop codon and in a translational frameshift. For this reason, the sequence presented here encodes an aberrantly rearranged human T-cell gamma chain.

Human T-cell gamma chain genes: organization, diversity, and rearrangement.

The human T-cell gamma chain genes have been characterized in an attempt to better understand their role in immune response. These immunoglobulin-like genes are encoded in the genome in variable, joining, and constant segments. The human gamma genes include at least six variable region genes, two joining segments, and two constant-region genes in germline DNA.

Partial primary structure of the alpha and beta chains of human tumor T-cell receptors.

The T-cell receptor for antigen (Ti) was purified from the human tumor cell line HPB-ALL. Amino-terminal sequence analysis of an acid-cleaved peptide of the Ti alpha chain showed that it is highly homologous to a putative murine alpha chain recently described. Amino-terminal sequence analysis of the Ti beta chain revealed that it shares 50 percent homology with the Ti beta chain amino acid sequences from two other human T-cell tumors.

Effects of monoclonal antibodies directed against murine T lymphocyte cell surface antigens on lymphokine production by cloned T lymphocytes reactive with class I MHC or Mls alloantigens.

Monoclonal antibodies recognizing murine T lymphocyte cell surface structures implicated in T lymphocyte-mediated cytolysis, including Lyt-2, L3T4, LFA-1, and a cytolytic T lymphocyte (CTL) clonotypic determinant, were used as probes to investigate the role of these structures in lymphokine production by T cell clones induced by antigen or lectin. The clone-specific antibody 384.5 bound to and inhibited antigen-induced lymphokine production by the L3 CTL clone, but did not affect lymphokine production by other T cell clones.

Contributions of T cell clones to an understanding of the T cell receptor for antigen.

Cloned populations of T cells have been used to derive clone-specific monoclonal antibodies. These antibodies influence the specific immunological functions of the cloned T cells, suggesting that these antibodies react with the T cell receptor for antigen. Immunoprecipitates have been obtained with some of these antibodies, and the characteristics of the polypeptides from different cells are surprising similar.

Antigen-reactive cloned helper T cells. II. Exposure of murine cloned helper T cells to IL 2-containing supernatant induces unresponsiveness to antigenic restimulation and inhibits lymphokine production after antigenic stimulation.

Cloned murine helper T lymphocytes (HTL) reactive to alloantigen or to ovalbumin (OVA) become unresponsive to antigenic restimulation after exposure to antigen or to culture supernatant fluids (SF) containing multiple lymphokine activities. Unresponsiveness is manifest by a failure of antigen-stimulated cells to incorporate thymidine or to produce lymphokines after antigenic challenge. Antigen-unresponsive HTL, however, will incorporate thymidine when exposed to an exogenous source of interleukin 2 (IL 2).

Monoclonal antibody to L3T4 blocks the function of T cells specific for class 2 major histocompatibility complex antigens.

The ability of antibody to Lyt-2 and to the newly described L3T4 antigen to block the functions of helper T cells with specificity for allogeneic class 1 or class 2 MHC subregion antigens was determined. Anti-Lyt-2 blocked both allohelp delivered by unprimed T cells and IL 2 production by primed T cells when the response was directed to class 1 MHC antigens, but had no effect when the response was directed to class 2 MHC or Mls antigens. Anti-L3T4 had reciprocal activity.

Characterization of the murine T cell surface molecule, designated L3T4, identified by monoclonal antibody GK1.5: similarity of L3T4 to the human Leu-3/T4 molecule.

Monoclonal antibody GK1.5 recognizes a previously undescribed murine T cell surface molecule, designated L3T4, which migrates on SDS-PAGE under reducing conditions as a single band with an apparent m.w.

Precursors of T cell growth factor producing cells in the thymus: ontogeny, frequency, and quantitative recovery in a subpopulation of phenotypically mature thymocytes defined by monoclonal antibody GK-1.5.

In this report, the ontogeny of precursors of T cell growth factor (TCGF)-producing cells in the mouse thymus was investigated using a recently described limiting dilution microculture system. In agreement with previous studies, in the adult thymus TCGF production by cells stimulated by alloantigens was largely the property of the Lyt-2-negative subpopulation. Furthermore, when Lyt-2-negative cells were stained with monoclonal antibody GK-1.

Evidence implicating L3T4 in class II MHC antigen reactivity; monoclonal antibody GK1.5 (anti-L3T4a) blocks class II MHC antigen-specific proliferation, release of lymphokines, and binding by cloned murine helper T lymphocyte lines.

Monoclonal antibody GK1.5 recognizes a determinant, designated L3T4a, on the murine T cell surface molecule L3T4. The expression of L3T4a by functional murine T cell clones appears to correlate primarily with class II MHC antigen reactivity rather than with functional phenotype.