Immune function alterations in mice tolerant to delta9-tetrahydrocannabinol: functional and biochemical parameters.

We studied the effect of acute (1 h) or chronic exposure (7 and 14 days) to delta9-tetrahydrocannabinol (delta9-THC) on immune parameters in male Swiss mice. One hour after a dose of 10 mg/kg s.c., the splenocyte proliferative response to ConA and NK activity were not inhibited, but there was a significant decrease in the production of IL-2. After 7 days of treatment, when mice were tolerant to delta9-THC-induced analgesia, these functional parameters were strongly inhibited and there was a persistent reduction in IL-2 and IFNgamma. With 14 days exposure to the drug, splenocyte proliferation was significantly reduced only with 5 microg/ml ConA, and NK activity was still significantly depressed (about 37%). IL-2 had returned to the control value, whereas IFNgamma was still 40% down. Flow cytometry analysis of spleen cell composition indicated no changes after the acute and 7 day treatments, but at 14 days there was a 20% decrease in the number of T lymphocytes, mirrored by a 26% increase of B lymphocytes. In conclusion, in vivo exposure to psychoactive doses of delta9-THC has profound effects on immune function. This implies some important questions in relation to the liberalization of marijuana and its therapeutic uses.

Severe Escherichia coli O111 septicaemia and polyserositis in hens at the start of lay.

Three very severe episodes of Escherichia coli infection in hens from the same farm, at the beginning of laying, are reported. They were characterized by no clinical signs, but sudden mortality, from 5 to 10%, with severe lesions of septicaemia and fibrinous polyserositis. A Gram-negative bacterium was consistently isolated in pure culture from tissues. Isolates were typed biochemically as E. coli, but they were lactose negative and non-motile. The serotyping tests typed the isolates as somatic group O111. The isolates were sensitive to enrofloxacin, amoxycil and colimycin, and partially sensitive to flumequine, all of which were used for therapy. The disease was reproduced experimentally in both specific pathogen free chickens and commercial layers by intramuscular inoculation of the E. coli, but only in some layers when inoculated by the oro-nasal route. The stress of the onset of lay seemed to be the most probable precipitating cause of the disease.

Cannabinoids inhibit nitric oxide production in bone marrow derived feline macrophages.

Feline immunodeficiency virus (FIV) infection causes a widespread natural immunodeficiency syndrome in cats that is considered a suitable animal model for studying human immunodeficiency virus (HIV) infection and pathogenesis. Short term cultures of bone marrow derived feline macrophages stimulated with recombinant feline interferon-gamma (r-IFN-gamma) and lipopolysaccharide (LPS) were shown to produce nitric oxide. Feline macrophages were shown to express cannabinoid receptors, and nitric oxide production decreased after in vitro exposure to synthetic cannabinoid CP-55940. Both cannabinoid receptors, CB1 and CB2, were involved in this process, since the inhibition was reversed by selective cannabinoid antagonists for both of these receptors.

Decreased expression of L-selectin (CD62L) on lymphocytes in enzootic bovine leukaemia.

Expression of L-selectin was determined by single- and two-colour immunofluorescence on granulocytes, peripheral blood mononuclear cells (PBMC) and blasts of bovine origin by means of a monoclonal antibody IVA94 which recognizes bovine L-selectin (CD62L). Cells were separated from peripheral blood of healthy cattle and colleagues infected with bovine leukaemia virus (BLV). BLV-infected animals comprised lymphocytotic and non-lymphocytotic cows. L-selectin was expressed on 90-98% of granulocytes in all tested animals. The percentage of PBMC expressing L-selectin was lower in cattle with persistent lymphocytosis than in non-lymphocytotic or BLV-free cattle, and inversely correlated with lymphocyte counts. The ratio of B lymphocytes stained for L-selectin was significantly decreased from 60.2 +/- 1.9% in BLV-free cattle to 43.8 +/- 3.6 and 22.5 +/- 5.7% in non-lymphocytotic and lymphocytotic cattle, respectively. B-lymphocytes stained for L-selectin exhibited about 50% reduction in L-selectin expression in BLV-infected cattle compared with BLV-free cattle, as judged by the mean fluorescence intensity (MFI). The percentage of L-selectin-positive PBMC not bearing surface immunoglobulin M (predominantly T lymphocytes) was comparable in BLV-free and BLV-infected cattle. However, L-selectin expression on T lymphocytes was reduced (about 50%) in BLV-infected cattle, as judged by the MFI. We suppose that BLV infection results in a decreased L-selectin expression on lymphocytes, and accordingly, it may contribute to deregulation of the host immune system.