Haptoglobin phenotypes differ in their ability to inhibit heme transfer from hemoglobin to LDL.

LDL oxidation plays a pivotal role in atherosclerosis. Excellular hemoglobin (Hb) is a trigger of LDL oxidation. By virtue of its ability to bind hemoglobin, haptoglobin (Hp) serves as an antioxidant. Oxidation of LDL by hemoglobin was analyzed to occur by heme displacement from methemoglobin lodged in LDL. The LDL-associated heme is disintegrated, and iron inserted this way in LDL triggers formation of lipid peroxides. The genetic polymorphism of haptoglobin was found to be a risk factor in the pathogenesis of atherosclerosis. Individuals with Hp2-2 have more vascular incidences as compared to those with Hp1-1. In the current study, oxidation of LDL by metHb was carried out at physiological pH without addition of external peroxides. Hb-derived oxidation of lipids and protein was found to be practically inhibited by Hp1-1 but only partially by Hp2-2. Heme transfer from metHb to LDL was almost completely omitted by Hp1-1 and only partially by Hp2-2. We concluded that partial heme transfer from the Hb-Hp2-2 complex to LDL is the reason for oxidation of LDL lipids as well as protein. These findings provide a molecular basis for Hp2-2 atherogenic properties.

Human T lymphotropic virus type 1 in a seronegative B chronic lymphocytic leukemia patient.

Human T lymphotropic virus type 1 (HTLV-1) is the etiological agent of adult T cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. HTLV-1 infection in patients with B cell-type chronic lymphocytic leukemia (B-CLL) is rare and has been reported only in areas in which HTLV-1 is endemic. In the present study, we detected HTLV-1 proviral DNA by polymerase chain reaction, using tax primers, in peripheral blood lymphocytes from a B-CLL patient, an immigrant to Israel, where HTLV-1 infection is not endemic. F344 rats injected intravenously with peripheral blood lymphocytes obtained from the patient developed HTLV-1 antibodies. Titers of antibody to HTLV-1 in the rat blood were 1:512 by particle agglutination; enzyme-linked immunosorbent assay and Western blotting were also positive. No antibody against HTLV-1 was demonstrated in the animal model after inoculation of either purified B lymphocytes from the B-CLL patient or peripheral blood mononuclear cells from healthy donors. This is one of the few studies showing the presence of HTLV-1 provirus in T lymphocytes of a B-CLL patient who had multiple infections, and died of salmonella sepsis, and the first report of HTLV-1 antibody induction in an animal model by inoculation of lymphocytes obtained from an HTLV-1-infected B-CLL patient.

Lack of HER-2/neu expression in Hodgkin and non-Hodgkin lymphoma.

OBJECTIVE: Overexpression of HER-2/neu oncoprotein, a tyrosine kinase receptor, occurs in a variety of human cancers and has been shown to play a critical role in their development. This overexpression is usually associated with poor clinical outcome. The significance of HER-2/neu in lymphomas is unknown. The aim of this study was to evaluate the expression of HER-2/neu in the malignant lymphomas: non-Hodgkin and Hodgkin lymphomas. METHODS: We studied formalin-fixed, paraffin-embedded tissue from 50 patients with lymphoma. Forty-two specimens were from patients with various types of non-Hodgkin lymphoma, and 8 were from patients with Hodgkin lymphoma. HER-2/neu expression was examined by an immunohistochemical technique using the HercepTest. RESULTS: None of the specimens demonstrated overexpression or even any expression of HER-2/neu. Reactive plasma cells showed cytoplasmic staining, which was not found in malignant plasma cells from patients with multiple myeloma. CONCLUSIONS: Non-Hodgkin and Hodgkin lymphomas do not express the HER-2/neu oncoprotein. This finding suggests that HER-2/neu does not play a role in these diseases.