Agenesis of the corpus callosum: magnetic resonance imaging

Three patients who had complete agenesis and two patients who had partial agenesis of the corpus callosum (ACC) underwent magnetic resonance (MR) imaging. In addition to excellent visualization of the indirect signs of ACC, direct vivid display (short T1) of the corpus callosum on sagittal images allowed better evaluation of subtle abnormalities than has been possible with other modalities. Associated abnormalities were also well-displayed. MR is the initial procedure of choice in evaluation of the corpus callosum.     

Establishment and characterization of an Epstein-Barr virus transformed cell line with strong phagocytic activity

An immunoglobulin M (IgM)-positive cell line, Ms 28, apparently spontaneously transformed by Epstein-Barr virus (EBV) was established from peripheral blood cells of a patient with immature myeloblastic leukemia. It has been characterized according to phenotype, cytochemistry, and membrane antigen pattern. The cell line expresses lymphoid markers like CD 19, CD 22, and CD 30 and synthesizes and secretes IgM. Monocyte markers CD 11c, CD 14, and CD 15 are absent. Neither interleukin-1 (IL-1), nor tumor necrosis factor (TNF-alpha) are produced. But Ms 28 cells show strong phagocytic activity and engulf Latex particles and sheep RBCs (SRBCs) that need not to be opsonized. The phagocytic activity can be inhibited by chloroquine. Both phagocytosis and EBV nuclear-antigen (EBNA) expression can be observed in one and the same cell. Ms 28 cells might be useful to study immunologic activities like antigen processing and presentation.     

Human immunodeficiency virus protease expressed in Escherichia coli exhibits autoprocessing and specific maturation of the gag precursor.

The mature gag and pol proteins of human immunodeficiency virus (HIV) and all retroviruses derive from large gag and gag-pol polyprotein precursors by posttranslational cleavage. A highly specific, virally encoded protease is required for this essential proteolytic processing. In this study, the HIV protease gene product was expressed in Escherichia coli and shown to autocatalyze its maturation from a larger precursor. In addition, this bacterially produced HIV protease specifically processed an HIV p55 gag polyprotein precursor when coexpressed in E. coli. This system will allow detailed structure-function analysis of the HIV protease and provides a simple assay for the development of potential therapeutic agents directed against this critical viral enzyme.     

Human herpesvirus 8 cellular immune responses in homosexual men.

Little is known about cellular immunity to human herpesvirus 8 (HHV-8), the virus associated with Kaposi's sarcoma (KS). T cell proliferative responses to purified HHV-8 were measured in homosexual men, a group with elevated HHV-8 seroprevalence and high risk of KS. None of 20 blood donor controls had T cell responses to HHV-8. Among human immunodeficiency virus (HIV)-negative homosexual men, 8 (42%) of 19 HHV-8 seropositive men responded as did 4 (16%) of 25 HHV-8 seronegative men. Among HIV-positive homosexual men, however, none of 21 HHV-8 seropositives had T cell responses to HHV-8, even though most responded to common recall antigens, and 10 had >/=400 CD4 cells/mm3. The results suggest that HHV-8 T cell proliferative responses are common in HIV-negative homosexual men and that HIV infection may be associated with diminished HHV-8 cellular immunity, possibly before there is substantial depletion of CD4 cells. If correct, this could explain why KS occurs relatively early in HIV infection/AIDS.