Histologic features of transplantable lymphoid tumor (Olson) during growth and regression induced by serum therapy

Susceptible 3-week-old chicks were inoculated with cells of an avian transplantable lymphoid tumor (TLT) and then treated with serum from immune chickens, serum from control chickens, or balanced salt solution. Progressive tumor growth was observed in chickens of all 3 treatment groups. Tumor growth was followed by regression only in chicks treated with immune serum. Regression was characterized by necrosis of tumor cells, muscle regeneration, and lymphocyte and plasma cell infiltration.