The proportions of B and T lymphocytes in lymphomas, peripheral nerves and lymphoid organs in Marek's disease.

The proportions of cells bearing B cell, T cell and immunoglobulin (Ig), cell membrane markers have been studied in chickens with Marek's disease (MD). The proportions of B, T and Ig-bearing cells were similar in lymphomas arising in various organs and in infiltrated nerves, irrespective of type of nerve lesion. T cells provided the major component, and B and Ig cells the minor components, of the lymphoid cell populations. Compared with the corresponding organ from uninfected control chickens, bursa and spleen from MD-affected birds showed increases in the proportions of T cells and decreases of B and Ig cells. In the bursa, and probably in the spleen, the increase in the proportion of T cells was caused by lymphomatous infiltration. In the thymus of MD-affected chickens the proportion of T cells was decreased, and of B cells increased.