Coma and axonal degeneration in vitamin B12 deficiency.

A 23-year-old woman with pernicious anemia, previously treated with folic acid, demonstrated an unusually rapid and severe course of neurologic deterioration. She was first seen with coma, myelopathy, and peripheral neuropathy. Her EEG showed repetitive nonperiodic suppression bursts, probably related to the severe impairment of consciousness. A sural nerve biopsy specimen revealed prominent axonal degeneration. With cyanocobalamin treatment, she regained normal mentation and the use of the upper limbs. She remains paraplegic, however, with a T10 sensory level.

Leukemic transformation in hrs mice occurs in an immature-nonactivated thymocyte subpopulation.

The murine leukemic strain HRS/J has an autosomal-recessive, mutant gene, hr, with homozygotes (hr/hr) having a 72% incidence of thymic leukemia at 18 months of age compared to 20% in heterozygotes (hr/+). This study was done to (a) determine if expression of thymocyte differentiation and murine leukemia virus (MuLV) antigens during leukemic transformation were different in hr/hr compared to hr/+ mice, (b) define the subpopulations that were targets for leukemic transformation, and (c) compare the results to reports in other leukemic strains. Flow cytometry analysis of thymus cell suspensions was done with anti-T-cell and anti-H-2 monoclonal antibodies, peanut agglutinin (PNA), and heteroantisera to MuLV antigens. Thymocytes of 1- to 3-month-old HRS/J mice were Thy 1.2+, Lyt 1+2+, H-2Kk-, and MuLV- with an immature-nonactivated phenotype, i.e., PNA+, and Iak-. Preleukemic and leukemic thymocytes showed diversity in expression of Thy 1.2 and Ly antigens with increased H-2Kk and MuLV expression. No differences in phenotype patterns were noted between hr/+ and hr/hr mice during the time course of leukemogenesis. Persistently high PNA/low Iak expression of preleukemic and leukemic thymocytes indicated that the target for HRS leukemic transformation was an immature-nonactivated thymocyte subpopulation in contrast to AKR/J mice in which leukemic transformation involves a mature-activated thymocyte subpopulation. These findings suggest that spontaneously generated leukemogenic viruses in HRS mice have tropism for thymocytes of an immature-nonactivated phenotype.

Thymic epithelium controls thymocyte expression of preleukemic phenotype and leukemogenic retroviruses.

Congenitally athymic AKR-streaker (nustr/nustr) mice were grafted separately with syngeneic or allogeneic, irradiated (1200 R) thymic reticuloepithelial (TRE) elements (stroma) or nonirradiated whole thymus grafts (control group) from N-tropic murine leukemia virus (MuLV) infection-susceptible (Fv-1n/n) or N-tropic-MuLV-infection-resistant (Fv-1b/n) murine strains. From 3 to 13 mo after grafting, the mononuclear cells repopulating the thymus grafts were stained with fluorescent monoclonal antibodies to thymocyte differentiation antigens, peanut agglutinin, and an antibody to MuLV antigens and were then analyzed by flow cytometry. Irradiated TRE of the Fv-1n/n genotype, whether from high or low leukemia-incidence strains, contained lymphoid cells of host (nustr/nustr) origin with alterations in thymocyte differentiation and MuLV antigen expression consistent with preleukemic changes. In contrast, transplanted TRE of the low leukemia-incidence Fv-1b/n genotype restricted preleukemic changes in thymocyte differentiation and MuLV antigen expression by lymphoid cells derived from the nustr/nustr host. Thus, nustr/nustr lymphocytes must infect susceptible TRE (Fv-1n/n) with N-tropic-MuLV before preleukemic changes occur in the mustr/nustr lymphocytes that later migrate to the thymus. Therefore, it was the radiation-resistant cells in the thymus that amplified or suppressed expression of AKR MCF retroviruses and the preleukemic phenotype, not the thymic lymphocytes. Thy-1.1+ splenocytes of ungrafted nustr/nustr mice were comparable in percentage to nustr/+ but were deficient in the Lyt-1+2- subpopulation and unresponsive to mitogens or alloantigens in vitro. Analysis of splenocyte cell surface markers, mitogen, MLC, and CML responses of Fv-1n/n-thymus-grafted nustr/nustr mice showed restoration of Lyt-1+2- cells to levels comparable to nustr/+ and reconstitution of in vitro proliferative and cytotoxic responses.

Histone variant composition of normal and leukaemic human lymphocytes: analysis by gel electrophoresis of whole cells and nuclei.

The histone variant composition of normal and leukaemic lymphocytes was analysed using a method which circumvented endogenous cellular proteolysis. Whole cells were solubilized in buffer containing protamine which released the histones from the DNA and allowed their immediate analysis by Triton X-100-acetic acid-urea gel electrophoresis. The results were comparable to those obtained with histones which had been acid-extracted from cells, nuclei or chromatin; however, the new method was more reproducible since proteolysis was controlled. By histone variant analysis, chronic lymphocytic leukaemia patients could be separated into two groups. One group had lymphocytes with a histone H2a variant ratio of about 1.0; this finding resembled lymphocytes (75-85% T cells) from normal individuals. The larger group had lymphocytes with a reproducibly lower histone H2a variant ratio; these cells had a relative increase in the second variant, H2a.2. The groups of patients could not be distinguished by clinical disease state. No other differences were noted in the histone variant composition of lymphocytes from normal and leukaemic individuals.

Adoptive immunotherapy of disseminated malignancies. Role of alien histocompatibility antigens on cancer cells and effectiveness of cells from alloimmunized donors.

The potential role of genetically inappropriate histocompatibility antigens on tumor cells as immunogens and targets for immunotherapy is reviewed. The evidence for immunologic mediation of tumor resistance following individual and pool alloimmunization both in vivo in murine and in vitro in murine and human systems is presented. The antileukemic reaction which follows transplantation of cells from alloimmunized MHC-compatible donors to mice bearing disseminated AKR leukemia is discussed in terms of antigen specificity, effector cell mechanisms and as an immunotherapeutic model. Possible advantages of utilizing cells from MHC-compatible allogeneic donors, rather than from tumor-bearing patients, for immunotherapy of human tumors are discussed. Although many investigators are assessing the significance of alien histocompatibility antigens on cancer cells and the mechanism by which alloimmunization induces antitumor immunity, it remains to be determined whether these efforts will result in an important advance in the treatment of patients with disseminated malignancies.

Characterization of alloimmunization-induced T lymphocytes reactive against AKR leukemia in vitro and correlation with graft-vs-leukemia activity in vivo.

We have reported that immunization of H-2k mice with lymphoid cells from various allogeneic strains induced a population of cells that could eliminate first-passage spontaneous AKR leukemia from the spleens of immuno-suppressed AKR (H-2k) hosts. In the present study, we examined the nature of the cells responsible for this graft-vs-leukemia (GVL) reaction and compared them to cytolytic cells detected in vitro. Spleen cells from alloimmunized CBA/J (H-2k) mice were selectively depleted of various subpopulations by treatment with antibody and complement (C), then tested in vivo for GVL reactivity. Cell suspensions depleted of Thy-1.2+, Lyt-1+, or Lyt-2+ lymphocytes had no significant GVL reactivity, whereas suspensions depleted of NK-1.2+ cells retained GVL reactivity. The GVL-reactive cells persisted in H-2-compatible donor mice for up to 56 days. Lyt-1+2+ lymphocytes that were cytotoxic for cultured AKR leukemia cells in vitro could be detected in the spleens of alloimmunized H-2-compatible mice after expansion of the cells in T cell growth factor. Using quantitative limiting dilution cytotoxicity assays, we found that the frequency of leukemia-reactive cytotoxic lymphocytes (CL) in the spleen showed a direct correlation with the GVL efficacy of the cells in vivo. Alloimmunization was essential for induction of the GVL-reactive cell population. CL in alloimmunized mice consisted of heterogeneous cytotoxic specificities; i.e., some CL were leukemia-specific, others lysed only nonleukemic AKR target cells, and a third group mediated killing of both leukemic and nonleukemic target cells. The CL appeared to be H-2 restricted and specific for non-H-2 antigens shared by the AKR leukemia and the alloimmunizing cells.

Surface phenotypes in T-cell leukaemia are determined by oncogenic retroviruses.

Spontaneous thymic leukaemia in experimental mice is the result of a complex series of genetically controlled events. An important step in this process involves the production by thymocytes of recombinant polytropic retroviruses (MCF viruses). These leukaemogenic agents arise by recombination of genes from the env regions of endogenous precursor viruses. Sequences in these regions encode the envelope glycoprotein gp70 (ref. 6). Thus far, each cloned isolate of recombinant virus from AKR and HRS/J mice has been found to possess unique oligonucleotide sequences in its env region, as well as clone-specific peptides in its gp70 (refs 7,8). Therefore, the polytropic viruses of these leukaemia-susceptible mice are extremely diverse. These findings suggest that random recombination of env genes gives rise to leukaemogenic polytropic viruses. McGrath and Weissman have proposed that thymocytes with cell surface receptors for the gp70 of a particular leukaemogenic virus are the target cells for malignant transformation by that specific virus. In view of the diversity of polytropic viral gp70, their hypothesis would predict extensive phenotypic diversity among spontaneous thymic leukaemias. In contrast, leukaemias induced by a particular leukaemogenic recombinant virus would always have the same phenotype. Here we verify these predictions experimentally.