Cellular Phenotypes in the Abomasal Mucosa and Abomasal Lymph Nodes of Goats Infected with Haemonchus contortus

The distribution of T-cell subsets (CD2, CD4, CD8, and γδ) and B cells (IgM) was examined at 3, 6, 10 and 13 days post-infection (dpi) in the abomasal mucosa and abomasal lymph nodes of goats primarily infected with Haemonchus contortus. In the abomasal mucosa a mild (3 and 6 dpi) or marked (10 and 13 dpi) increase of T cells, particularly CD4 + and γδ + lymphocytes, was observed, whereas the increase in CD8 + cells was less pronounced. B cells and IgG + plasma cells also showed a marked increase in the abomasal mucosa at 10 and 13 dpi. The abomasal lymph nodes showed an increase in size, particularly at 10 and 13 dpi, and a decrease in the proportion of T cells, particularly CD8 + lymphocytes, due to the increased proportion of B cells. The proportion of CD4 + and γδ + lymphocytes did not change significantly during the infection in the abomasal lymph nodes, but their absolute numbers were augmented as a result of the enlargement of the nodes. The results revealed a strong cellular and humoral immune response during the early post-infection stages. However, as indicated by the worm burdens, this rapid host response was unable to induce larval expulsion.