Cytolytic activity of mitogen activated old and young mouse spleen cells against tumor target cells expressing high or low levels of Fas antigen

Abstract

Sensitivity of Fas expressing tumor cells (high levels in

Faster cytotoxicity with age: Increased perforin and granzyme levels in cytotoxic CD8+ T cells boost cancer cell elimination

“…However, the endpoint lysis results depend very strongly on the target-to-killer cell ratio and the type of target cells itself. Similar observations regarding endpoint lysis were observed in previous studies conducted with entire splenocyte populations (Saxena & Adler, 1999;Saxena et al, 1988). Despite the similar endpoint lysis, we were able to show for the first time differences in the killing kinetics of murine CTLs against different tumor cell lines.…”

“…Quantitative PCR assay detected significantly higher mRNA expression of FasL (Figure S5a) but no changes in NKG2D (Figure S5c) in CD8 + T cells of the elderly mouse compared to the adult. Although the expression of Fas on P815 cell is limited (Saxena & Adler, 1999), the receptor‐mediated pathway may contribute or support the faster killing kinetics in CD8 + T cells from the elderly. We directly assessed the contribution of Fas–Fas ligand interactions and the influence of NKG2D on the CD8 + T cell‐mediated cytotoxicity by treating cells with neutralizing antibodies against FasL (10 and 20 μg/ml) and NKG2D (10 μg/ml).…”

“…Since aging results in a continuous remodeling and adaptation of the immune system and affect CD8 + T cells, more profound information is necessary to improve their impaired function. Despite the evidence that the immune system of the aged is significantly altered, there is increasing data suggesting that particularly CD8 + T cells can remain functionally intact and show even enhanced cytotoxicity (Saxena & Adler, 1999; Saxena et al, 1988). Functional properties of each expanded T cell subset may pave the way for a more detailed evaluation of the effects of aging‐related changes on the subset contribution to in vitro‐expanded T cells.…”

Hydrolysis of tumor cell lipids after CTL-mediated death

“…To eliminate the apoptoticinduced cell death by the predominant death ligand, fasL, on the surface of the activated T cell, we used P815 target cells. P815s have low expression of the Fas receptor and would be less inclined to undergo apoptotic death in the presence of T cell death ligands (25). This would reduce the possibility of [ 3 H]-apoptotic bodies interfering with our results.…”

“…51 Cr cytotoxicity assays Lysis of target cells was determined by redirected lysis in a similar manner to the [ 3 H]-oleic acid release assays. The tumor target cells were P815s, which express low levels of the Fas receptor on their surface (25) and express Fc receptors. The P815 cells were labeled with Na 2…”