concanavalin-a and Lice-Infestations

Proliferative responses of peripheral blood and prescapular lymph node lymphocytes from 8 B. ovis-infested and 8 naive lambs to concanavalin A (Con A) and soluble antigen of B. ovis were examined in vitro. The numbers of lice and the extent of cockle were also assessed on each lamb. Prescapular lymph node lymphocytes from infested lambs showed significantly higher responses to B. ovis antigen than those from naive lambs. Only a marginal difference was observed between infested and naive lambs in the response of lymphocytes from peripheral blood. Proliferative responses to Con A by prescapular lymph node or blood cells were not significantly different between groups. The results indicated a relationship between the intensity of louse infestation and the proliferative response of prescapular lymph node lymphocytes to B. ovis antigen.

Topics: Animals; Antigens; Concanavalin A; Lice Infestations; Lymph Nodes; Lymphocyte Activation; Phthiraptera; Sheep; Sheep Diseases

The in vitro proliferation assay was used to determine lymphocyte responsiveness to soluble antigen of B. ovis and to Concanavalin A (Con A) in peripheral blood, spleen and various lymph nodes from B. ovis-infested and naive lambs. From March to July, an assay of monthly blood samples showed generally higher proliferative responses to antigen and Con A in B. ovis-infested than naive lambs. The proliferative response of cells from the skin-draining prescapular lymph nodes to B. ovis antigen was significantly higher in B. ovis-infested than naive lambs. Responses of cells from the medial iliac, mediastinal and mesenteric lymph nodes (which do not receive lymph from the skin) and spleen showed no significant differences between groups. Within the B. ovis-infested lambs, the response of cells from the prescapular lymph node was significantly higher than that from any other lymphoid organ examined. Responsiveness of the prescapular, medial iliac and mesenteric lymph node and spleen cells to Con A was not significantly different between groups, while mediastinal lymph node cells showed a significantly higher response in B. ovis-infested lambs. The data indicate that the antigen-specific cellular immune response is operating mainly locally, at the level of the skin and draining lymph nodes. Responses to the T cell mitogen Con A did not support non-specific immunodepression as reported in other ectoparasite/host systems.

Topics: Animals; Antigens; Concanavalin A; Female; In Vitro Techniques; Lice Infestations; Lymphocyte Activation; Lymphocytes; Lymphoid Tissue; Phthiraptera; Seasons; Sheep; Sheep Diseases