Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 3, 1996
Publication Date: N/A
Interpretive Summary: The nematode Ostertagia ostertagi is the predominant cause of parasite-induced production losses in cattle throughout temperate regions of the world. This predominance is partially due to the slow and incomplete development of protective immune responses. The mucosal intraepithelial (IEL) and lamina propria (LPL) lymphocytes carry out specific effector functions, protecting the host against invasion by potential pathogens. In this study, the phenotypic characterization and changes in these populations of cells in uninfected and O. ostertagi infected animals were reported. It was observed that infected animals showed increased levels of immunoglobulin-bearing cells (IgM), gamma delta T cells and activated T cells. The increased levels of B cells could be a reflection of polyclonal B cell activation. The increase of gamma delta T cells was not correlated with protective immunity, which implies that additional factors may influence protective immune responses against O. ostertagi. These findings represent an important step in identifying the basis for delayed development of protective immunity against this parasite.
Technical Abstract: Isolation and characterization of surface marker phenotypes of intraepithelial (IEL), lamina propria (LPL) and abomasal lymph node lymphocytes (ABLN) from uninfected calves was conducted, and the dynamics of change in these populations during the course of a primary Ostertagia ostertagi infection were defined. To obtain viable IEL and LPL from the abomasal mucosa of cattle, a modified isolation method was developed. The recovery of lamina propria cells was accomplished by an enzymatic method, using dispase. Further purification of lymphocytes from the whole population was performed over discontinuous percoll gradients. The phenotypic characterization of abomasal lymphocytes was accomplished by indirect immunofluorescence staining. Within 3 weeks of infection, the number of lymphocytes recovered from the abomasal lamina propria (LP) was dramatically increased when compared to uninfected animals. Laser flow cytometric analysis demonstrated increased levels of immunoglobulin-bearing cells gamma delta T cells, and activated T cells in IEL, LPL and ABLN in the infected animals. The greatest changes took place during the first days of infection and these changes were apparent throughout the 28 days covered by the experiment.