[Influence of host genotype in the development of metastasis in a transplantable lymphoma in rats]

For the purpose of investigating the influence of the host genotype in the metastatic process, the frequency of lymph nodes metastases of a transplantable rat lymphoma (L-TACB) in relation to tumor growth and to capacity of rejection was studied in the inbred lines m, eR and eS and in the F1 hybrids m x eR, m x eS and eR x eS. L-TACB is a spontaneous poorly differentiated lymphoma that appeared in the peritoneal cavity of a rat of the inbred line e; since 1969 it has been maintained by subcutaneous grafting in e rats. The tumor was inoculated by trocar and measured with a caliper every 3 to 4 days, the size expressed in mm2 (large diameter x minor diameter). Percentages of takes, regression, lethality and axillary and/or inguinal lymph nodes metastases were registered. The maximum size (TMx) reached by the primary tumor, in animals with (TMx-CM) and without metastasis (TMx-CM) were recorded. Tumor size (TMx) in animals of line m was greater (p less than 0.01) than in rats of subline eR while tumor regression was significantly less in eR (29.7%) than in m (72.7%) and eS (100%) (p less than 0.001), suggesting that tumor growth rate was independent of the capacity of tumor rejection. Rats of genotypes m and eS had a great capacity of tumor rejection; however, the hybrid m x eS showed a low percentage of regression (17.2%) (p less than 0.001). This result reveals an opposite effect produced by the genetic interaction of the m and eS parental lines.(ABSTRACT TRUNCATED AT 250 WORDS)