Lymph nodes from K1 transgenic mice showing sheets of plasma cells and loss of normal architecture and increased VEGF production as detected by immunohistochemical staining and ELISA. (A) Lymph node tissue sections from a nontransgenic mouse (Ai) and a K1 transgenic mouse (Aii) were stained with hematoxylin and eosin and examined under a light microscope. Immunohistochemically stained sections of a lymph node from a nontransgenic mouse (Aiii) and a K1 transgenic mouse (Aiv) with anti–VEGF antibody were examined under a deconvolution microscope as described in “Materials and methods.” The original magnification was ×400. Results are representative of 3 separate experiments. (B) Equal weights of minced lymph nodes from nontransgenic (NT) and K1 transgenic mice were cultured overnight in 1 mL growth medium, and the VEGF levels were analyzed in 50-μL aliquots of culture supernatants by ELISA. Results represent the means (± SD) of VEGF concentrations in lymph nodes from 6 mice per group. There were statistically significant increases in VEGF concentration in the lymph nodes from K1 mice (^*P = .009).