Lysosomes in Rat Thoracic Duct Lymphocytes

Abstract

10 acid hydrolases known to be lysosomal in other tissues were detected in rat thoracic duct lymphocytes (TDL). Except for cathepsin D, all these enzymes occurred in lower levels in TDL than in rat spleen. Fractionation by means of differential centrifugation revealed two types of distribution patterns. Most of the total cathepsin D activity appeared in a high-speed supernatant (S), whereas the other acid hydrolases associated mainly with a high-speed pellet (P). Further studies by isopycnic centrifugation in a sucrose density gradient showed that all the enzymes, including a small portion of cathepsin D, sedimented around a modal density of 1.18. In contrast, most cathepsin D activity was recovered in a soluble, unsedimentable form. These results suggest the presence of two populations of lysosomes. Because the possibility could be excluded that other cell types contaminated the lymphocyte preparations, it is concluded that both lysosomal populations arise from TDL.

A Study of Proteolysis as a Possible Mechanism for T‐Cell‐Mediated Target Cell Lysis

“…Before discussing the effects of protease inhibitors on the q'totoxic capacity of CTL. the following control experiments will be shown: [1] TLCK as used under our conditions did indeed inhibit in vitro tryptic digestion of iodinated BSA (see Table I); [2] only at very high concentrations did TLCK and TPCK have a significant effect on spontaneous chromium release of target cells (see Table 11); and [3] TLCK had no direct toxic effect on CTL manifesting itself by decreased viability: recovery of untreated CTL after 24 hr of culture was 83%; recovery of CTL treated for 2 hr phatf-buffered saline with 40 i,,£ trypsin (Sigma), type XI. for I hr at 37°C with various concentrations of inhibitor (L-I-tosylamide-2-leucyl chloromcthyl ketone; TLCK).…”

“…Papain digestion was carried out for 16 hr at 37°C according to the method of Porter (2)(3)(4). using I mg papain (Calbiochem, San Diego, Calif.) per 55 mg immunoglobulin.…”

“…Recently, it has been established that small thoracic duct lymphocytes of the rat contain relatively high levels of lysosomal proteases (3,4). Since release of lysosomal enzymes is a well-documented phenomenon for granulocytes and macrophages (10,12,13,31), it seemed possible that release of lysosomal proteases into the extracellular cleft between target ceil and CTL occurs during cell killing.…”

Response of Bovine Alveolar Macrophages in Vitro to Welding Fume Particles

“…Lactate dehydrogenase (LDH) assays were carried out as described by Schnyder and Baggiolini (15) and N-acetyl-p-glucosaminidase (3-NAG) was assayed fluorimetrically (16) as described by Bowers (17). Cell number counting by hemacytometer and trypan blue exclusion (0.5% in balanced salt solution, BBS) were carried out on both populations.…”

Elektronenmikroskopische Lokalisation von Thiaminpyrophosphatase und Nucleosiddiphosphatase in Lymphozyten

“…In der menschlichen Milz zeich nen sich T-zellabhängige und B-zellabhängige Regionen durch den Be sitz charakteristischer Enzyme aus [24]. Periphere Lymphozyten scheinen dagegen nur sehr spärlich mit nachweisbaren Enzymaktivitäten ausgestat tet zu sein [1,5,7,17]. Während beim Meerschweinchen Thymozyten in der Thymusrinde eine hohe Aktivität der alkalischen Phosphatasen besit zen, konnte dieses Enzym in peripheren T-Lymphozyten nicht mehr nach gewiesen werden [17,32].…”