The response of the Harderian gland of the fowl to antigen given by the ocular route i. Histological changes

During a study of local immunity in the fowl, histological examination was made of the Harderian and lachrymal glands after eye-drop application of sheep erythrocytes (SRBC), or live vaccine strains of Newcastle disease virus (NDV) and infectious bronchitis virus (IBV). As judged by counts of lymphoid foci and Russell body (RB-containing cells each treatment resulted in heightened lymphoid activity and increase in plasma cell numbers in both glands. However, the changes were more apparent in the lachrymal gland which normally carries few immuno-competent cells. After stimulation, immunoglobulin (Ig)-containing secretion accumulated in the Harderian gland. Aerosol or intravenous infection of normal chickens with lentogenic NDV induced a moderate or slight cellular reaction respectively in the paraocular glands. However, no histological change resulted from intravenous inoculation of SRBC in either intact or splenectomised birds. In the Harderian gland, epithelial vacuolation and a 25-30 fold increase in RB cell numbers were sequels to ocular infection with H120 IBV. It is suggested that IBV may directly damage immunocompetent cells.