Walker 256 tumor MHC class I expression during the shift from A variant to the immunogenic AR variant

Tumor growth characteristics of the Walker 256 AR tumor, a regressive variant of the rat Walker 256 A tumor

“…The results confirmed the AR variant as an immunogenic variant of the W256 tumor. The improved immunogenicity of W256 AR variant was also consistent to previous studies showing that W256 AR variant presented higher numbers of MHC class I positive cells than W256 A variant (Schanoski et al, 2004).…”

“…In total, 62% of the W256 AR tumor-bearing rats presented complete tumor regression, but none of the Walker 256 A tumors regressed. Regardless of the low number of references reporting spontaneous regression of W256 tumor, it was possible to establish a regressive tumor variant, named AR, which was originated by serial passages of the W256 A tumor cells in the ip cavity of Wistar rats (Schanoski et al, 2004). The shift on the characteristics of W256 tumor, from a progressive variant to an immunogenic and regressive variant by serial ip passages of the tumor cells, could also explain the spontaneous regressions of the W256 tumors reported by Jensen and Müntzing (1970).…”

“…Walker 256 AR variant (W256 AR) was obtained after serial passages of W256 A tumor cells in the ip cavity of rats, as previously described (Schanoski et al, 2004). Both tumor variants are currently kept in the laboratory frozen in liquid nitrogen and maintained through sc (W256 A variant) or ip (W256 A variant and W256 AR variant) passages in rats.…”

“…This was characterized by a significant increase in red blood cell osmotic fragility with marked spleen hypertrophy in the host. Besides, MHC class I positive tumor cells significantly increased in the AR variant compared to the W256 A variant (Schanoski et al, 2004). The objective of the present work was to evaluate the W256 AR variant after sc injection in Wistar rats aiming at a better characterization of the regression phenomenon.…”

“…This phenomenon is poorly documented (Cavalcanti et al, 2003;Schanoski et al, 2004;Jensen and Muntzing 1970) and has been associated to the rat strain (Schmid et al, 1966;Jaganjac et al, 2008). We have recently reported the generation of a regressive W256 variant named AR (Schanoski et al, 2004). The AR variant was obtained after serial passages of W256 A tumor cells in the intraperitoneal (ip) cavity of rats, where it grows as an ascitic tumor.…”