The response of the Harderian gland of the fowl to antigen given by the ocular route. II. Antibody production.

After ocular administration to young chickens of sheep erythrocytes (SRBC), Newcastle disease virus (NDV), infectious bronchitis virus (IBV) or Mycoplasma gallisepticum, homologous antibody was detected in serum and in saline extracts of Harderian glands. Parenteral immunisation with SRBC or NDV stimulated moderately high serum antibody titres but did not evoke a measurable antibody response by the Harderian gland.

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.

Immunocompetent cells in avian paraocular glands.

A study was made of the Harderian and lachrymal glands of fowls, pheasants, turkeys and pigeons. Accumulation of heterophils and plasma cells commenced soon after hatching, was well advanced by four weeks of age and was always greater in the Harderian than in the lachrymal glands. Plasmablasts entered via interlobular capillaries, maturing as they migrated to and congregated round the lobular collecting ducts. Their secreted immunoglobulin was readily demonstrated in the duct lumen. Russell body containing cells of diverse morphology were a consistent feature of infiltrated Harderian glands. Though scant in the glands proper, lymphoid tissue was abundant in the walls of their draining ducts.

Further observations on functional deletion of paraocular glands in the fowl (Gallus domesticus).

Methods are described for inoculation of the fowl Harderian gland with sclerosing reagent and for its surgical excision. Though very destructive the former procedure proved the less reliable in achieving the gland's complete functional deletion. Three weeks after surgical removal of the Harderian glands the lachrymal glands of 10-week-old fowls were heavier and contained more immunocompetent cells than the glands of intact and sham operated birds. When adult birds deprived of both paraocular glands were given sheep erythrocytes or Newcastle disease virus by eye drop they developed slightly higher than normal titres of serum antibody but failed to produce lachrymal antibody.

Plasma cells in vertebrate paraocular glands.

The Harderian and lachrymal glands of eight mammals and two reptiles were examined histologically for plasma cells and the extent of infiltration compared to that in the Harderian gland of the fowl. Moderate accumulations were observed in one or both glands of the goat, sheep, cow, horse, dog and pig, but only few cells were present in the glands of the mouse and rabbit. No plasma cells were encountered in snake glands but some were detected in both glands of lizards. It is suggested that glandular secretions contribute to local immunity.

Removal of the lachrymal gland and ligation of the Harderian gland duct in the fowl (Gallus domesticus): procedures and sequelae.

Surgical methods are described for removal of the lachrymal gland and ligation of the Harderian gland duct in the fowl. Total or partial cystic degeneration of the Harderian gland and loss of immunoglobulins from lachrymal fluid was evident in three of six adult birds 10 weeks after operation. Functional deletion of these paraocular glands is thus feasible and can be used for investigations of local immunity of the oculonasal region.

Local immunity in Newcastle disease: some recent experiments.

Following primary exposure by the ocular route to lentogenic Newcastle disease virus (NDV) the lacrymal fluid, saliva and tracheal washes of three-week old specific pathogen free chickens acquired specific virus-neutralizing activity which considerably exceeded transudation of circulating antibody. All three secretions contain IgA which, at least in saliva, accounted for 85% of its activity, the remanider being due to IgG. Antibody in secretions limited, but did not prevent, reinfection of the trachea when birds were challenged two weeks later. In contrast to an elevation of circulating antibody titre, challenge induced only a repeated primary response in secreted antibody. Ocular infection induced marked lymphoid and plasma cell activity in the Harderian gland which is a major source of specific antibody in lachrymal and possibly other fluids. Functional ablation of the gland can be effected by occlusion of its draining duct, providing a means for evaluation of its immunological significance.

Observations on the serological and dermal responses of turkeys to a single subcutaneous inoculation of inactivated Newcastle disease vaccine in mineral oil adjuvant.

Each of 10 growing turkeys given a primary subcutaneous inoculation of inactivated Newcastle disease vaccine in mineral oil adjuvant responded with the production of virus-neutralizing (VN) and haemagglutination-inhibiting (HI) antibodies. Biphasic modulation of the serological response was more evident with HI than with VN antibodies. At the inoculation site there developed a discrete swelling that regressed within the 10 week period of observation. Histologically the swelling consisted of an inflammatory granulomatous reaction, with an accumulation of macrophages containing phagocytosed droplets of vaccine. Plasma cells were also present. No inflammatory swelling developed in chickens and pheasants similarly vaccinated but comparable cellular changes were noted around the dispersed vaccine.