Antigen-specific stimulation of amino acid transport in bovine lymphocytes

Treatment of bovine lymphocytes isolated from animals which were either infected with Mycobacterium bovis or sensitized to a purified protein derivative (PPD-B) from this organism induced an increase in the transport of alpha-aminoisobutyric acid (AIB) and alpha-methylaminoisobutyric acid (MeAIB). PPD-B did not stimulate these transport activities in lymphocytes from nonsensitized animals. The transport stimulation was first measurable after about 7 hours of treatment, reached about a two-fold enhancement after 20 hours, and continued to increase to 30- to 40-fold after 6 days. The stimulation of AIB transport was inhibited by both ouabain and cycloheximide. Experiments to determine transport system specificities in nonstimulated lymphocytes showed that MeAIB transport was primarily by the Na+-dependent, A-system, and leucine transport was mostly by Na+-independent system(s). In contrast, AIB transport was about 25% by the A-system, 25% by at least one Na+-dependent, non-A-system, and 50% by one or more Na+-independent system(s). Analysis of the three components of AIB transport after treatment with PPD-B showed that: 1) transport by both the A-system and the Na+-independent system(s) was stimulated; 2) A-system transport was stimulated to a larger extent than Na+-independent transport; and 3) Na+-dependent, non-A-system transport was not stimulated significantly.