Development and characterization of an IL-2-dependent bovine CD4+ lymphoblastoid T-cell line

A bovine IL-2-dependent lymphoblastoid T-cell line (BLTC) was developed and established from peripheral blood mononuclear cells stimulated with Con A, and subpassaged in conditioned media prepared from Con A-activated bovine lymph node cells. The BLTC cell line is IL-2 dependent, requiring exogenous IL-2 either in the form of recombinant bovine or human IL-2 or conditioned media prepared from Con A-stimulated bovine lymph node cells. Conditioned media prepared from mononuclear cells from other species, such as dogs and rats, were without any stimulatory effects. The growth of these cells was lectin-independent, and monokines such as IL-1 beta and TNF-alpha, or conditioned media from LPS-stimulated macrophases failed to support their growth. Immunophenotyping showed that over 90% of the cells were CD2+, CD3+, and CD4+, 25% were CD5%, less than 2% were CD8+, and less than 2% were CD20+. The cells were negative for the gamma delta 215/300 kDa T-cell markers and the 75/110 kDa monocyte markers. The growth of these cells was inhibited by dibutyryl cAMP in the presence or absence of IL-2, and stimulated by the phorbol ester, PMA, in the absence but not in the presence of IL-2. The effects of IL-2 and PMA were blocked by the protein kinase C inhibitor, H-7, suggesting that IL-2 signaling is closely associated with the PKC activation pathway.