Rat B cells: identity of immunoglobulin-bearing cells with a population of lightly uridine-labeled cells

The role of de novo purine synthesis in lymphocyte transformation

Genetic defects in purine metabolism are associated with severe immunodeficiency. Adenosine deaminase deficiency impairs the function of both B- and T-lymphocytes whereas in purine nucleoside (inosine) phosphorylase deficiency there is more severe impairment of T-lymphocyte functions than of B-lymphocyte functions. The relative unimportance of the salvage pathway catalysed by hypoxanthine-guanine phosphoribosyltransferase is shown by the normal responses of T-lymphocytes from patients with the Lesch-Nyhan syndrome to antigenic and mitogenic stimulation. A mild deficiency of B-lymphocyte function is found in these patients. Agents inhibiting the de novo pathway of purine synthesis, including azaserine, 6-mercaptopurine and azathioprine in low doses, block the responses of normal human lymphocytes to mitogenic stimulation. These observations emphasize the importance of the de novo pathway of purine synthesis in lymphocyte responses to antigenic and mitogenic stimulation. There is considerable heterogeneity in the amount of labelled uridine incorporated into human and rat lymphocytes. This does not appear to reflect only a difference between T- and B-lymphocytes

The migration of lymphocytes across specialized vascular endothelium VII. The migration of T and B lymphocytes from the blood of the athymic, nude rat

The primary migration of lymphocytes from the blood was compared in nude rats and in euthymic rats. The flatter endothelium in the post-capillary venules (PCV) in the lymph nodes of nude rats was as efficient as the high endothelium of PCV in euthymic rats at capturing both T and B lymphocytes from the blood, although lymphocytes took a longer time to cross the PCV wall in nude recipients. The organ distribution of both lymphocytes and lymphoblasts ([125I]UdR-labelled cells) was broadly similar in nude and euthymic recipients. A second aim was to compare B and T lymphocytes with respect to the rate and sites at which they leave the blood after intravenous injection. As judged by sampling venous blood, B lymphocytes left the blood faster, but this was partly attributable to a larger intravascular pool of B lymphocytes in small blood vessels, especially in the lung. Thoracic duct lymphocytes from nude rats collected under standard conditions (16 h, O degrees C) entered the cervical lymph nodes very poorly, but when lymphocyte transfer was performed under more physiological conditions entry of B lymphocytes into lymph nodes was about half that of T lymphocytes. B lymphocytes did show a slight preference for entry into Peyer's patches compared with lymph nodes.

Pathologic effects in rodents exposed to sodium combustion products

Three species of rodents exhibited respiratory distress when exposed to aerosols of sodium combustion products, the major constituent of which was shown to be sodium carbonate. At the higher doses, animals died during or shortly after 2 hr exposures. Lesions, primarily involving the pharynx and larynx, included accumulation of mucus, vesiculation, and mucosal edema. Other lesions included edema and vesiculation of the anterior trachea, hemorrhage in the lungs, and severe gastric tympany. Basal epithelial cells of the posterior pharynx and anterior trachea had enlarged mitochondria following exposures of 1 hr or more.

Non-specific acid esterase activity in rat lymphocytes

In a first night's collection of rat thoracic duct lymphocytes B- and T-cells were distinguished on cytocentrifuge smears by complementary markers: B-cells by rosette-formation with Staphylococcus aureus Strain Cowan 1 armed with rabbit antiserum to rat F(ab')2 and T-cells by high uptake of 3H-uridine demonstrated by autoradiography. On incubation of the cytocentrifuge smears for demonstration of alpha-naphthyl-acetate esterase (ANAE)-activity, most B-cells showed large, intense colour deposits often located in the uropod. T-cell ANAE-activity on the other hand was variable, possibly due to variations in experimental conditions. When present, the T-cell colour deposits were small, dot-like and of low intensity. ANAE-activity may then be used to differentiate between rat T- and B-cells, being a marker for the latter cell type. This is unexpected as others have reported that ANAE-activity is specific for T-cells in mouse and man. Studies with inhibitors indicate that the rat B-cell enzyme belongs to the acetylesterases.

The host component of the popliteal lymph node graft-versus-host (GVH) reaction. Identification of cells in the node and kinetics of cell proliferation

The cellular composition of rat popliteal lymph nodes undergoing a GVH reaction was examined. The great majority of cells isolated from the nodes were lymphocytes, while the contribution of phagocytic cells was negligible (less than 5%). Both T and B cells were present in GVH nodes. However, the proportion of B cells was higher than in normal lymph nodes (40-50% vs 30%). Cells synthesizing DNA were enumerated autoradiographically in sections of GVH nodes up to day 7 of the response. A significant increase in the proportion of 3H thymidine labelled cells had already been found on the third day of the GVH response, before lymph node enlargement was apparent. Of the differnt days tested a maximum of 6% labelled cells was found on day 7. Liquid scintillation counting of cell suspension from such nodes showed an even higher increase in 3H thymidine incorporation in GVH vs normal nodes. These findings indicate that cell proliferation is a central mechanism behind the lymph node enlargement.