Phosphoantigens (PAgs) activate Vγ9Vδ2 T lymphocytes, inducing their potent and rapid response in vitro and in vivo. However, humans and nonhuman primates that receive repeated injections of PAgs progressively lose their Vγ9Vδ2 T cell response to them. To elucidate the molecular mechanisms of this in vivo desensitization, we analyzed the transcriptome of circulating Vγ9Vδ2 T cells from macaques injected with PAg. We showed that three PAg injections induced the activation of the PPARα pathway in Vγ9Vδ2 T cells. Thus, we analyzed the in vitro response of Vγ9Vδ2 T cells stimulated with a PPARα agonist. We demonstrated that in vitro PPARα pathway activation led to the inhibition of the BrHPP-induced activation and proliferation of human Vγ9Vδ2 T cells. Since the PPARα pathway is involved in the antigen-selective desensitization of human Vγ9Vδ2 T cells, the use of PPARα inhibitors could enhance cancer immunotherapy based on Vγ9Vδ2 T cells.
The in vitro effects of iridovirus isolated from catfish on head kidney lymphocyte activity were examined in carp, rainbow trout and sheatfish. Mitogenic proliferative assay was used to demonstrate an immunosuppressive effect of iridovirus on the proliferative response of head kidney lymphocytes stimulated by ConA and LPS. The production of IL-2-like protein by head kidney lymphocytes stimulated by ConA or iridovirus-like agent was also examined in three species of fish. The preliminary in vitro study demonstrated an inhibitory effect of the iridovirus on the proliferative response of head kidney lymphocytes and on the IL-2-like protein production in carp, rainbow trout and sheatfish, but the highest suppressive effect was observed on sheatfish cells. The results suggested that the early-induced iridovirus pathogenicity is the inhibition of the proliferative response and cytokines production by lymphocytes.
The study aimed at immunocytochemical evaluation of the cellular expression of two cytokines, IL-2 and IL-12 in lung carcinoids (n = 10), following the earlier demonstration of two markers of endocrine tumours (chromogranin A and NSE — neuron-specific enolase). In the immunocytochemical studies the classical avidin-biotinylated peroxidase (ABC) technique was used. Results of the tests were semiquantitatively appraised employing the IRS scale. In 9/10 cases intense reaction (score: 6–12 points) was noted for both lung neuroendocrine markers. In all cases of carcinoma co-expression of IL-2 and IL-12 was demonstrated in cells of the tumours. The cytokines showed a cytoplasmic localisation of mean (score: 3–4 points) or high (score: 6–12 points) intensity of reaction. Our studies point to a possible role of the two cytokines in the proliferation of lung neuroendocrine carcinomas but more detailed analysis is required on a broader material.
Regulatory effect of CD25, an activation antigen the alpha subunit of interleukin 2 receptor (IL2R) on the activity of natural killer (NK) cells was studied in fifty elderly (57-70 years old) and fifty young people (19-35 years old). Cytotoxic NK activity was assessed by 51Cr release assay, the levels of interleukin 2 (IL2) and tumour necrosis factors alpha (TNFalpha) were measured using bioassays and expression of CD16 and CD25 proteins by flow cytometry. Low NK activity in the elderly was associated with decline of full health, lowered serum concentration of IL2 and increased production of TNFalpha during NK reaction. Inhibition of TNFalpha activity by anti-TNF monoclonal antibody suppressed exclusively NK activity of low NK responders. Moreover, stimulation in vitro of blood mononuclear cells, with TNFalpha induced in the elderly low NK responders a significantly higher increase of the CD25 expression on the surface of NK cells as compared with that in the elderly high responders. Since the CD25 molecule constitutes a subunit of the high affinity receptor, binding IL2 to immunocompetent cells, its increased expression on NK cells of low NK responders would enable them to bind even low amounts of the endogenous IL2 available in this group of the elderly. Thus, an overproduction of TNFalpha seems to be a mechanism compensating, in the non-fully healthy elderly, for the decreased IL2 production, promoting efficient cytotoxic reaction.