TNF and Lymphadenopathy: Similarly to the clinical data, Tg26 mice with leukemia/lymphoma displayed: (i) splenomegaly, lymphadenopathy and extra nodal enlargements in the liver and the gastrointestinal tract (Figure 1); (ii) increased lymph node expression of HIV-1 genes (Table 1), increased expression of HIV proteins p17, gp120 and nef in mice developing lymphoma (Figure 2); and (iii) significant increases in serum cytokines including IL-6, IL-10, TNF-α, IL-12 and IL-13 (Figure 3).