Differential Lymphokine Expression by Rat Antigen-Specific CD4+ T Cell Lines with Antigen and Mitogen

Retinal soluble antigen (S-Ag) and purified protein derivative (PPD)-specific T cell lines established from Lewis rats were used to study the pattern of lymphokine expression to see if it varied with the inducing stimulus. Lymphokine mRNA expression was detected by PCR combined with Southern analysis after 6-hr stimulation and protein secretion assessed by bioassays at 24 hr poststimulation. S-Ag-specific T cell lines when stimulated with antigen expressed IL-2, IFN-γ, and IL-4 mRNA, whereas only IL-2 and IFN-γ could be detected in the supernatants. This is in contrast to the findings after stimulation of the PPD cell lines with PPD where IL-4 could be detected in the supernatants. The time course studies (3, 6, 24, 48, and 72 hr) with one of the S-Ag-specific T cell lines showed that S-Ag activation did not induce any detectable IL-4 bioactivity. However, when the S-Ag T cell line was stimulated by Con A or PMA, IL-4 was detected in the supernatants following Con A activation, suggesting that the way in which the T cell is activated has an effect on its resultant lymphokine secretion.