In tuberculous cattle transiting early peripartum period specific in vitro PBMC stimulation induces an increase of CD14 expressing cells, B B2 cells, and CD25 cells with half IFNγ production

Abstract

The objective of this study was to evaluate activation, expansion, and cytokine production after Mycobacterium bovis in vitro specific stimulation of peripheral blood mononuclear cells (PBMC) subpopulations from Argentinian Holstein cows that reacted to the bovine purified protein derivatives (PPDb) caudal fold skin test and were transiting the early peripartum period (EPPp). Flow cytometry, interferon gamma (IFNγ) production, and metabolic activity assessed peripheral blood mononuclear cells (PBMC) stimulation. The study enrolled 19 Argentinian Holstein cowsolder than two years classified into four groups, one of PPDb reactors that transited the EPP period (PPDbEPPp) (n=5), another of PPDb reactors that did not transit the EPP period (PPDbNoEPPp) (n=5), the third of no PPDb reactors that transited the EPP period (NoPPDbEPPp) (n=5), and the last of no PPDb reactors that did not transit the EPP period (NoPPDbNoEPPp) (n=4). PPDb reactors came from two dairy farms with endemic bovine tuberculosis (TB) and nonreactors from a dairy farm free of PPDb reactors for 12 years. In PPDb reactors, CD14 expressing cells increased ignificantly after specific stimulation. In PPDbEPPp group, B B2 cells expanded significantly (p=0.004), and cells with the activation marker CD25 (or interleukin-2 receptor α chain) expanded significantly (p= 0.03) with half IFNγ production. Results from this study suggest that in naturally M. bovis infected dairy cows EPP period would not influence the presentation of PPDb by CD14 expressing cells. However, a deregulated immune response might occur because B B2 and CD25 lymphocyte subsets expanded with a lowered IFNγ production.