No abstract

Exogenously added prostaglandin El or E2 inhibited the blastogenic response of Mycobacterium bovis-sensitized bovine peripheral blood lymphocytes stimulated with concanavalin A, phytohemagglutinin, or M. bovis purified protein derivative as measured by [3H]thymidine uptake. The kinetics of the response showed that prostaglandins must be added to lymphocyte cultures within hours after mitogen or antigen addition to achieve maximum suppression of [3H]thymidine uptake. Addition of prostaglandins 24 h after the addition of mitogens or antigens resulted in considerably less suppression, supporting a hypothesis that prostaglandins initiate an early series of events which ultimately control lymphocyte blastogenesis rather than directly inhibit deoxyribonucleic acid synthesis.

Earlier work in our laboratory demonstrated that naturally occurring reveromycin A (Rev A) causes apoptosis in osteoclasts without accompanying necrosis. Rev A death effects in both normal and diseased joint cells were investigated in this study. A dose of 10 μM Rev A did not cause apoptosis nor necrosis in monolayer chondrocytes, even at pH 6.8, a pH mimicking that of an inflamed joint. In contrast, at the acidic pH Rev A did induce significant apoptosis (fourfold increase at 48 h of treatment, P < 0.005) in normal synoviocytes without accompanying necrosis. Western blot of the normal synoviocyte proteins revealed that cytochrome c levels were not significantly changed over the time course of treatment nor did caspase 8 activity increase; therefore, Rev A appears to exert this apoptotic effect through a mechanism independent of the classical intrinsic and extrinsic pathways. Fibroblast-like synoviocytes isolated from rheumatoid arthritis patients (RAFLS) as well as normal human fibroblast-like synoviocytes (NHFLS), cells known to play key roles in arthritic joint pathology, were also subjected to Rev A treatment at both physiologic and acidic pH's. Neither apoptosis nor necrosis was induced in either RAFLS or NHFLS. Parallel mitomycin C treatment of NHFLS induced both apoptosis and necrosis. Comparative structure-activity analyses of Rev A and mitomycin C revealed that Rev A is less likely to cross the cell membrane at near neutral pH. Collectively the data reveal that a physiological dose of Rev A under acidic conditions induces normal synoviocytes to undergo apoptosis while pathologic fibroblast-like synoviocytes are resistant to apoptosis and necrosis.

Kaneene, J.1980. Application of a whole-blood lymphocyte stimulation test in detection of Brucella infection in an outbreak. Vet. Sci. Commun., 4: 59-66.A whole-blood lymphocyte stimulation test (WBLST), the standard plate and tube agglutination tests, the Brucella buffered antigen test, the 2-mercaptoethanol agglutination test, the Rivanol plate precipitation test and bacteriological isolation were utilized in a brucellosis outbreak investigation in a beef herd. Three of the animals were classified as not infected serclogically. However, these 3 animals were classified as infected on the WBLST, and Brucella abortus biotype I (not strain 19) was isolated from their lymph nodes. The WBLST exhibited significant sensitivity in this investigation and more observations of this nature might strengthen the application of this assay in similar situations.

Osteoporosis is a prevalent disease with several current treatments. However, these treatments can have harmful long‐term side effects on individuals utilizing them. Reveromycin A (Rev A) is a natural compound that specifically causes apoptosis in osteoclasts but not osteoblasts. To further test whether Rev A can be a safe osteoporosis treatment without detrimental effects in the surrounding joint, the compound’s ability to induce apoptosis and necrosis in ATDC5 murine chondrocytes and HIG‐82 rabbit synoviocytes was measured. Inflammatory joint disease is known to accompany osteoporosis; consequently, Rev A‐induced cell death was characterized in each of these two cell lines under both physiological pH and a pH of 6.8 to mimic the pH of an inflamed joint. After treatment, morphology was assessed through phase contrast microscopy, apoptosis was measured through colorimetric caspase 3 activity assay, and necrosis was quantitated by use of a lactate dehydrogenase (LDH) release assay. Six hours of ten micromolar Rev A treatment did not significantly induce chondrocyte apoptosis, chondrocyte necrosis, or synoviocyte necrosis at either pH. Synoviocyte apoptosis was not induced by Rev A at physiological pH, but at a pH of 6.8, Rev A induced apoptosis compared to untreated by 4.9–fold (p<0.005). The results suggest that Rev A may have undesirable apoptotic effects in synoviocytes of the joint under acidic conditions. Grant Funding Source: Supported by grants from the Indiana Academy of Science and the Hodson Summer Research Institute