The application of banding techniques to the study of tumor chromosomes during the past 10 yr has yielded extensive data defining the types of chromosome changes that occur in human hematopoietic and other tumors. Chromosome changes characterize most tumors and exhibit a high degree of nonrandomness; in some tumors, this nonrandomness is defined by the tumor-inducing agents, while in others, it is defined by target cells of tumorigenesis. These observations led to the suggestion that chromosome abnormalities impart a selective advantage to the cells in which they occur and hence are of importance in the development of tumors. The mechanisms by which cells carrying chromosome abnormalities gain selective advantage are beginning to become apparent as the recently acquired data on the molecular genetics of neoplastic transformation are considered in conjunction with cytogenetic data. Activation of cellular oncogenes and overproduction of their products has been shown to be a key step in some types of neoplastic transformation. Chromosome abnormality is suggested to accomplish this step by either causing alterations in oncogene dosage or by activating normally quiescent oncogenes by bringing them into the transcriptional control of active genes. The paradigm for the latter model is the development of human and murine B-cell neoplasms in which specific translocations transfer c-myc from its constitutive site to a site next to the immunoglobulin genes. The chromosomal positions of several oncogenes have now been determined, and the elucidation of their fate in association with chromosome abnormalities in tumor cells can be expected to clarify mechanisms of oncogenesis.

Fifteen compounds reported to be inhibitors of gelation or sickling were studied by standard methods. These tests included (1) the determination of the solubility of deoxyhemoglobin S or Csat, (2) evaluation of sickling in whole SS blood at various pO2s, (3) measurement of the oxygen affinity of hemoglobin and blood, and (4) examination of red cell indices and morphology. Among the 4 noncovalent agents tested, butylurea was the most potent inhibitor of gelation and sickling in vitro; however, relatively high concentrations were required compared to the covalent agents. In the latter group, bis-(3,5 dibromosalicyl)-fumarate, nitrogen mustard, and dimethyladipimidate were especially effective inhibitors of gelation and/or sickling. All of these compounds require further development before they can be considered for clinical use.

The selectivity of monoclonal antibody J-5 (anti-gp 100, common ALL antigen) for normal and leukemic hemopoietic cells has been investigated. J-5 gave concordant reactions with rabbit anti-cALL, coredistributed on the cell surface, and precipitated a similar if not identical glycoprotein from leukemic and normal tissue. Normal, immature lymphoid cells reactive with J-5 were detected in bone marrow and in fetal thymus. In marrow they were largely coincident with the TdT+ population. J-5 defines a major subgroup of ALL (common ALL) with a favorable prognosis. Of 853 non-ALL acute leukemias investigated, 80 were J-5 positive. These included 14 cases diagnosed as AML, 51 TdT+ blast crises of CGL, and 15 cases diagnosed as "AUL." Of the 14 J-5+ AML, 13 were subsequently rediagnosed either as cALL (10 cases) or mixed lymphoid-myeloid leukemias (3 cases). One-hundred forty-three cases of mature lymphoid cell leukemia (91 B, 52 T) were investigated with J-5; 3 cases only, of disseminated B lymphoma, were positive, albeit weakly. A higher proportion of follicular lymphomas are, however, J-5 positive when studied in sections of biopsy material. A similar pattern of selective reactivity was observed in a series of leukemia/lymphoma cell lines. These studies emphasize the diagnostic value of monoclonal anti-cALL reagents.

A small quantity of extracellular calcium is required for the stimulation of lymphocytes by mitogens such as plant lectins. Lectin binding to the lymphocyte surface and early postbinding events that eventually lead to DNA synthesis are calcium dependent. Mitogenic lectins such as PHA and Con-A rapidly increase the size of an exchangeable pool of cell calcium and cause a smaller rise in intracellular ionized calcium. The increase in ionized calcium is so small (100-200 nM), however, that no increase in total cell calcium is measurable. When lymphocytes are stimulated by a lectin, the rate of calcium entry into the cell increases, but the plasma membrane calcium extrusion pump can prevent the total cell calcium from increasing measurably. The calcium ionophore A23187 is a lymphocyte mitogen and causes an increase in the exchangeable, ionized, and total cell calcium. The former two effects may be causal in mitogenesis; the latter effect is cytotoxic. With A23187 treatment, the rate of calcium influx exceeds the maximum rate of the plasma membrane extrusion pump and cell calcium increases in proportion to the concentration of A23187. The mitochondria, by virtue of their high membrane potential, provide a sink for the buffering of cytoplasmic calcium after A23187 treatment. Thus, the plasma membrane or mitochondria regulate the distribution of lymphocyte calcium when the cell is stimulated by mitogenic lectins or ionophores. The evidence strongly suggests that an alteration in calcium pools or an increase in cytoplasmic ionized calcium plays a role in the initiation of the biochemical reactions that lead to mitogen-induced lymphocyte proliferation in vitro and, perhaps, to the immune response.

Major advances have been made in the past 10 yr in both the understanding of the biologic characteristics of acute nonlymphocytic leukemia and in the treatment of patients with this disease. Advances in the biologic characteristics include: a better understanding of the nature of leukemic cell proliferation and differentiation; a clearer description of the morphological, histochemical, and ultrastructural characteristics of leukemic cells; a recognition that a high percentage of patients may have specific cytogenetic abnormalities; and a recognition that biochemical differences exist between acute nonlymphocytic leukemia (ANLL) and acute lymphoblastic leukemia (ALL). Today, over 70% of children with ANLL can be induced into a complete remission and over 25% are remaining in a continuous remission for over 2 yr. In spite of these improved results, the best method of extending remissions is unknown. It is unlikely that better results of therapy will be achieved in the future by tailoring the treatment according to the biologic characteristics of the patient, since it appears that ANLL is a heterogeneous group of diseases.

The M-2 protocol (vincristine, cyclophosphamide, BCNU, melphalan, and prednisone) was administered monthly to 63 evaluable patients with advanced chronic lymphocytic leukemia. Complete remission (absence of all clinical and bone marrow evidence of leukemia) and partial response (greater than 50% decrease in organ enlargement and reduction of WBC count to below 15,000 x 10(6)/liter) were achieved in 17% and 44%, respectively, for a total response rate of 61%. The median survivals from therapy of patients achieving a CR, RR, or no response were 73+, 40, and 14 mo respectively. The median survival time from onset of treatment for stages II, III, and IV disease were 47, 20 and 19 mo, respectively, which was not statistically different from historical controls. However, when untreated patients are compared to this latter group, a significant survival advantage from diagnosis was found (p = 0.01), stressing the importance of prior therapy as the only unfavorable prognostic factor. Although complete remissions in CLL, as reflected in apparently normal bone marrow B-lymphocyte markers, can be induced wih acceptable morbidity, the majority of patients relapse after cessation of therapy. An alternative approach to the M-2 protocol will be needed to eradicate the disease.

Using a panel of monoclonal antibodies, we have studied cell surface antigens of infiltrating mononuclear cells in skin biopsies from patients with cutaneous T-cell lymphoma (CTCL) and compared them with the T-cell surface phenotype seen in benign cutaneous T-cell infiltrations (e.g., contact dermatitis, delayed hypersensitivity skin tests, granuloma annulare) and in dermal infiltrates of lymphomatoid granulomatosis patients. We found that unlike circulating CTCL (Sézary) cells, CTCL cells infiltrating skin epidermis frequently expressed the T-cell antigen 3A1. Cutaneous infiltrates in 10 patients with mycosis fungoides (MF) and 1 patient with Sézary syndrome were OKT4 (inducer T cell), OKT8 (suppressor/cytotoxic T cell); 2 patients with MF were OKT4-, OKT8; and one MF patients's skin T cell were OKT4-, OKT8+. Similar to CTCL infiltrating cells, most of the benign skin T-cell infiltrates were usually 3A1+. OKT4+, and OKT8-. Our study shows the complex nature of T-cell antigen patterns in inflammatory and malignant skin T-cell infiltrations. We demonstrated that the CTCL the skin epidermal infiltrating T-cell phenotype is not invariate, and in many cases, is similar to the phenotype of clinically benign cutaneous T-cell infiltrations.

Disseminated intravascular coagulation (DIC) is caused by a variety of underlying disorders, and criteria for diagnosis are not well defined. However, the most helpful are a low platelet count, positive plasma protamine test, and fibrinogen and fibrin degradation product levels viewed in the context of the patient's underlying disease. The cornerstone of therapy is prompt treatment of the underlying disease and elimination of the trigger mechanism. Additional treatment must be individualized, and generalizations are difficult to make. However, if the patient has low hemostatic factors and is actively bleeding or requires an invasive procedure, then replacement with the appropriate hemostatic factors should be tried. Heparin is indicated in patients with purpura fulminans and venous thromboembolism, but there is little evidence that heparin reverses organ dysfunction associated with DIC. In addition, heparin is also probably indicated in patients with retained dead fetus and hypofibrinogenemia prior to induction of labor, excessive bleeding associated with a giant hemangioma, and neoplastic disease, particularly promyelocytic leukemia. Although the use of heparin in acute forms of DIC remains controversial, the majority of studies suggest that it is not helpful. The role of antithrombin III (AT-III) concentrates is unknown, but they theoretically may be helpful when DIC is associated with very low AT-III levels, as is seen in liver disease.

A small proportion of patients with acute or chronic leukemia has an extraordinarily high blood leukocyte count. These high counts can result in a very high fractional volume of leukocytes (leukocrit), which is also a function of the mean leukocyte volume in different types of leukemia. Despite a high fractional volume of leukocytes, bulk viscosity of blood is usually not increased because a decrement in the fractional volume of erythrocytes accompanies the increase in leukocytes. Nevertheless, the excessive numbers of leukocytes present two major problems: first, they can seriously affect flow in the circulation of the lung, brain, and less often, other organs by obstructing microchannels or by forming aggregates and white thrombi in small veins. Moreover, leukemic blasts may compete for oxygen in the microcirculation and they may be invasive, damaging vessel walls. Second, their rapid destruction in response to cytotoxic drugs causes metabolic disturbances, especially uric acid accumulation, which can lead to obstructive uropathy.

The discoid shape of blood platelets is supported by a circumferential bundle of microtubules. Removal of the microtubules by an antimitotic drug, vincristine, is associated with loss of lentiform appearance, formation of tubulin paracrystals, a depressed response to aggregating agents, and impaired secretory activity. Recent studies have suggested that the action of vincristine on platelet secretion and aggregation is directly related to its action on microtubules, while other work had indicated that the antimitotic drug prevents the release reaction by inhibiting prostaglandin synthesis. The present study has examined the influence of taxol, a microtubule stabilizing agent, on the response of platelets to vincristine. Taxol completely prevented vincristine-induced shape change, microtubule disassembly, and tubulin paracrystal formation, even at concentrations one-tenth that of the antimitotic drug. Pretreatment with vincristine to dissociate microtubules and convert tubulin to crystals before exposure to taxol did not affect altered shape or tubulin paracrystals, but did cause assembly of free pools of tubulin into tubular polymers. Studies of physiology confirmed that vincristine, in amounts that remove microtubules, depresses platelet aggregation and secretion, effects that could be overcome by increasing agonist concentration. Although completely preventing microtubule dissociation, taxol had no corrective influence on vincristine-induced inhibition of platelet function. Biochemical studies revealed that vincristine concentrations that disassembled microtubules and blocked secretion did not inhibit conversion of 14C-arachidonic acid to thromboxane B2. The findings suggest that vincristine inhibits platelet function through some mechanism other than disassembling microtubules, but the other mechanism does not involve inhibition of prostaglandin synthesis.

The generation of murine monoclonal antibodies reactive with human leukemia and lymphoma cells has recently led to clinical trials that have begun to evaluate the use of these reagents in the treatment of various leukemias and lymphomas. Several of these studies have demonstrated that infusion of monoclonal antibody can cause the rapid and specific clearance of leukemic cells from the peripheral blood. Intravenously administered antibody also rapidly binds to bone marrow lymphoblasts, and in one instance, has resulted in the partial regression of tumor cell infiltrates in lymph nodes and skin. Unfortunately, clinically significant responses have not in general been achieved, but these clinical studies have identified specific factors that result in the development of resistance to antibody-mediated lysis in vivo. These factors include the presence of circulating antigen, antigenic modulation, reactivity of monoclonal antibody with normal cells, immune response to murine antibody, and the inefficiency of natural immune effector mechanisms. Current research is now being directed towards developing methods to circumvent each of these obstacles. Future clinical studies utilizing antibodies in vitro or with different specificity may demonstrate greater therapeutic efficacy. In addition, monoclonal antibodies can be used as carriers of other cytotoxic agents and in conjunction with other agents that will reduce the total load. Monoclonal antibodies represent new and powerful reagents that may in the near future become an additional therapeutic modality for patients with malignant disease.

Throughout their evolution, mammalian hemoglobins have acquired a broad repertoire of functional properties well suited to the internal milieu of the red cell. Mammals display a wide range in whole blood oxygen affinity dependent on three major factors: the intrinsic oxygen affinity of the hemoglobin, the level of red cell 2,3-DPG, and the response of the hemoglobin to 2,3-DPG. The concentration of 2,3-DPG varies among groups of mammals. Those animals (cats and ruminants) that have very low levels of this intracellular mediator have hemoglobins of intrinsically low oxygen affinity that fail to respond to the addition of 2,3-DPG. Mammals that have adapted to various types of hypoxia tend to have increased oxygen affinity, primarily mediated through reduced levels of red cell 2,3-DPG. In contrast, mammals who are experimentally subjected to low oxygen tensions develop decreased oxygen affinity owing to increased red cell 2,3-DPG. Mammals employ one of three different mechanisms for the maintenance of higher oxygen affinity of fetal red cells, compared to maternal red cells. Many of these phenomena can be satisfactorily explained at the molecular level but their adaptational significance is less clear.