A comparative study on the xenotransplantability of human solid tumors into mice with different genetic immune deficiencies

These experiments set out to assess the role of NK and B cells in the resistance of nude mice to human tumor xenotransplantation. The transplantability of 9 fresh and 8 cultured human tumors was compared in 2 strains of mice with different genetic immune deficiencies: athymic NCr/Sed (nu/nu) nude mice, and nude‐beige‐xid (N:NIH‐nu‐bg‐xid/Sed mice). Flow cytometric studies showed both strains to be deficient in Thy. 1.2 (T) cells and unresponsive to stimulation by Concanavalin A (Con A) or direct T‐cell‐receptor triggering with anti‐CD3. The number of B cells was similar in the 2 strains, but the response to lipopolysaccharide (LPS) was markedly reduced in the nude‐beige‐xid animals. The number of asialoGM₁,‐positive cells (predominantly NK) detected by flow cytometry was also reduced in the nude‐beige‐xid mice. The transplantability of the human tumors was found to be equivalent in the 2 strains. Quantitative cell‐transplantation assays performed for 2 of the tumor cell lines did not reveal any subtle transplantation advantage for the more broadly immune‐deficient animals. No evidence could, therefore, be found to suggest that NK or B cells were major determinants of human tumor xenotransplantability in these strains of mice.