THORACIC LYMPHATIC CANNULATION FOR THE STUDY OF PULMONARY IMMUNE-RESPONSES IN LUNG LYMPH OF CALVES

Objective-To develop a system for analysis of immune response variable s in the lymph draining the lung and to establish baseline data for cl inically normal calves. Design-Surgery was performed on 6 calves to in sert a cannula into the efferent lymphatic duct of the caudal mediasti nal lymph node to create a long-term thoracic lymph fistula draining t o the exterior. Lymph was collected daily, and on the fifth postoperat ive day, calves were exposed to an aerosol of cell culture medium (moc k infection). For the next 10 days, lymph was collected for analysis a nd, on the tenth day, necropsy was performed. Animals-Six 6- to 8-week -old Holstein bull carves. Procedures-Daily lymph samples were evaluat ed for: flow rate; total and differential cell counts; and IgG, IgM, I gA, IgE, and protein concentrations. On days -4, -1, 1, 4, 7, and 10, cells were stained and quantitated by fluorescence-activated cell sort er analysis for T, B, CD4+, and CD8+ cells. Blood lymphocytes were eva luated 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 co ncentrations in lymph and plasma did not indicate a protein drain. Alt hough mean lymphocyte counts reflected a slight gradual decrease in ly mph lymphocytes, this effect was not apparent in every calf, nor was t he effect seen in blood lymphocytes. There were no significant changes in IgG, IgM, IgA, or IgE concentration, with the exception of IgA con centration 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 co nstant al near 2. Conclusions-Creation of a thoracic lymphatic fistula appears to be a useful technique for studying effects of lung infecti on on immunologic variables, with potential application to bacterial a nd viral respiratory tract diseases. Clinical Relevance-Thoracic lymph atic cannulation can be used in studies to determine pathogenic mechan isms in respiratory tract disease and to develop more effective vaccin es against respiratory tract pathogens.