Changes in red blood cell osmotic fragility induced by total plasma and plasma fractions obtained from rats bearing progressive and regressive variants of the Walker 256 tumor

Abstract

Two variants (A and B) of the widely employed Walker 256 rat tumor cells are known. When inoculated sc, the A variant produces solid, invasive, highly metastasizing tumors that cause severe systemic effects and death. We have obtained a regressive variant (AR) whose sc growth is slower, resulting in 70-80% regression followed by development of immunity against A and AR variants. Simultaneously with the beginning of tumor regression, a temporary anemia developed (~8 days duration), accompanied by marked splenomegaly (~300%) and changes in red blood cell osmotic fragility, with mean corpuscular fragility increasing from 4.1 to 6.5 g/l NaCl. The possibility was raised that plasma factors associated with the immune response induced these changes. In the present study, we identify and compare the osmotic fragility increasing activity of plasma fractions obtained from A and AR tumor bearers at different stages of tumor development. The results showed that by day 4 compounds precipitating in 60% (NH 4 ) 2 SO 4 and able to increase red blood cell osmotic fragility appeared in the plasma of A and AR tumor bearers. Later, these compounds disappeared from the plasma of A tumor bearers but slightly increased in the plasma of AR tumor bearers. Furthermore, by day 10, compounds precipitating between 60 and 80% (NH 4 ) 2 SO 4 and with similar effects appeared only in plasma of AR tumor bearers. The salt solubility, production kinetics and hemolytic activity of these compounds resemble those of the immunoglobulins. This, together with their preferential increase in rats bearing the AR variant, suggest their association with an immune response against this tumor.

Effect on osmotic fragility of red blood cells of whole blood submitted to vibrations in an oscillating platform

“…Paired t-test was used to compare each one of the intervals; I, II and III (Cavalcanti et al, 2003) between control and each one of the treated isolated sets (control and 10 Hz, and control and 20 Hz). A significance level at p < 0.05 was adopted.…”

“…In both evaluations, an increase in the osmotic fragility of the RBC was found. Figure 4 shows the statistic analysis of the intervals of the NaCl concentrations proposed by Cavalcanti et al (2003) in the osmotic fragility curve. It shows a significant (p<0.05) hemolysis in interval II in both frequencies utilized.…”

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

“…Additionally, W256 AR tumor regressions are associated with normal CD4 + /CD8 + ratio, whereas tumor continuous growth is associated with a significant reduction in the CD4 + /CD8 + ratio (Guimarães, 2000). W256 AR tumor-bearing rats also present plasma compounds resembling immunoglobulin, around the same period (day 12-14) when tumor regressions started (Cavalcanti et al, 2003). The precise mechanism underlying the origin of W256 AR variant is unknown.…”

“…Nevertheless, spontaneous W256 tumor regression can occur. 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).…”

Osmotic and morphological effects on red blood cell membrane: action of an aqueous extract of Lantana camara

“…The supernatant at 0.9% NaCl was considered the blank for the preparation, because it has no hemolysis. In according to fragility curve tendency, three intervals were determinated: interval I between 0.12 and 0.36% NaCl, interval II between 0.36 and 0.60% NaCl and interval III between 0.60 and 0.90% NaCl (Cavalcanti et al, 2003). After measuring of osmotic fragility, "fragility curves" were drawn by plotting the percentage of lysis or hemolysis (% hemolysis) for each tube (relative to 100% hemolysis tube) and the corresponding concentration of NaCl.…”