Fmr1 knockout mouse has a distinctive strain-specific learning impairment.

The Fmr1 gene knockout mouse is a model for the human Fragile X mental retardation syndrome. Fmr1 knockout mice with a C57BL/6-129/OlaHsd hybrid background have been reported to have only a very mild deficiency in learning the Morris water maze task. We compared the effect of this knockout mutation on learning in mice with either an FVB/N-129/OlaHsd hybrid background or a C57BL/6 background.

Defective monocyte chemotaxis in active lepromatous leprosy.

This study of monocyte chemotaxis in leprosy patients showed a significant inverse correlation (p less than 0.05) of chemotaxis and the bacterial index (BI) (N = 22). In addition, there was a significant inverse correlation (p less than 0.

Secretory leukemic B cells express T cell markers in vitro. A phenomenon suppressed by TPA.

Immunological and biochemical markers of leukemia/lymphoma cells have provided valuable insight into hematopoietic malignancy and normal differentiation. The general assumption is that as early lymphoid cells become committed towards terminal differentiation they lose their capacity for bimodal differentiation and cells become restricted to B or T cell development and function. We have observed that phenotypically "late" leukemic B cells close to secretory stage can spontaneously express mature T cell antigens (T11, T4 and T8) after culture in vitro.

Tpa-induced maturation in secretory human B-leukemic cells in vitro: DNA synthesis, antigenic changes, and immunoglobulin secretion.

The maturation of malignant cells in response to differentiating agents is interesting as a model of normal differentiation. The response of a freshly explanted neoplastic population of phenotypically well-characterized lymphosarcoma cell leukemia blasts was studied after incubation with the differentiating agent TPA (12-0-tetradecanoyl-phorbol-13-acetate). Terminal differentiation was assessed by measuring the immunoglobulin secreted in culture supernatants and the production of intracytoplasmic immunoglobulins.

E-receptors mediate the attachment of activated T-lymphocytes to human red blood cells: evidence from studies with monoclonal antibodies and simple sugars.

Lectin-stimulated human T-lymphocytes display the capacity of forming stable E-rosettes with sheep red blood cells (SRBC) and of forming rosettes with allogeneic and autologous erythrocytes (RBC). Fractionation experiments indicated that the same subpopulation of lymphocytes displays both of these characteristics. Exposure of T-lymphocytes stimulated with concanavalin A (Con A) or phytohemagglutinin (PHA) to T11 monoclonal antibody (directed against the E-receptor) completely blocked the formation of rosettes with human RBC.