Evidence of decreased concanavalin A induced suppressor cell activity in the peripheral blood and pulmonary lymph nodes of sheep with ovine progressive pneumonia.

Concanavalin A (Con A) induced suppressor cell activity was evaluated in a group of ovine progressive pneumonia virus-antibody positive sheep (OPPV+). Decreased levels of suppressor activity were observed in the peripheral blood and regional pulmonary lymph nodes of animals with clinical and pathological evidence of ovine progressive pneumonia (OPP) when compared to animals with no lesions and animals with caseous lymphadenitis involving the lungs and pulmonary lymph nodes. Decreased levels of Con A stimulated lymphocyte proliferation was also observed in the peripheral blood and iliac lymph nodes of sheep with OPP. Sheep with OPP were found to be hypogammaglobulinemic. Sera from OPPV+ sheep had no effect on T and B cell mitogen stimulated responses of lymphocytes from sheep seronegative for antibodies to ovine progressive pneumonia virus (OPPV-) when compared to normal sheep serum.