Thoracic lymphatic cannulation for the study of pulmonary immune responses in lung lymph of calves

Abstract

Objective: To develop a system for analysis of immune response variables in the lymph draining the lung and to establish baseline data for clinically normal calves.

Design: Surgery was performed on 6 calves to insert a cannula into the efferent lymphatic duct of the caudal mediastinal lymph node to create a long-term thoracic lymph fistula draining to the exterior. Lymph was collected daily, and on the fifth postoperative day, calves were exposed to an aerosol of cell culture medium (mock infection). For the next 10 days, lymph was collected for analysis and, on the tenth day, necropsy was performed.

Animals: Six 6- to 8-week-old Holstein bull calves.

Procedures: Daily lymph samples were evaluated for: flow rate; total and differential cell counts; and IgG, IgM, IgA, IgE, and protein concentrations. On days -4, -1, 1, 4, 7, and 10, cells were stained and quantitated by fluorescence-activated cell sorter analysis for T, B, CD4+, and CD8+ cells. Blood lymphocytes were evaluated on days -1 and 10 for comparison.

Results: Flow was established for up to 25 days, with a mean rate between 11 and 22 ml/h. Protein concentrations in lymph and plasma did not indicate a protein drain. Although mean lymphocyte counts reflected a slight gradual decrease in lymph lymphocytes, this effect was not apparent in every calf, nor was the effect seen in blood lymphocytes. There were no significant changes in IgG, IgM, IgA, or IgE concentration, with the exception of IgA concentration in 1 calf that developed an abscess at the cannulation site. The T-cell subset absolute numbers of CD4+ and CD8+ cells decreased slightly over time, but the CD4(+)-to-CD8+ cell ratio remained almost constant at near 2.

Conclusions: Creation of a thoracic lymphatic fistula appears to be a useful technique for studying effects of lung infection on immunologic variables, with potential application to bacterial and viral respiratory tract diseases.

Clinical relevance: Thoracic lymphatic cannulation can be used in studies to determine pathogenic mechanisms in respiratory tract disease and to develop more effective vaccines against respiratory tract pathogens.