Gene expression in CD8 and CD4 T-cell populations following activation with the calcium ionophore A23187.
We have hypothesized that functional maturation of T lymphocytes can be dissected into a series of discrete stages. For example, activation of T lymphocytes with the calcium ionophore A23187 drives CD8+ T cells to become dividing blasts, referred to as 'pre-effector' cells in that these blasts do not express cytolytic function but are driven by IL-2 to do so. Here we characterize via Northern blots the functional maturation of CD8+ and CD4+ T-lymphocyte populations which have been activated via A23187 followed by stimulation with IL-2. Previously we have reported that no detectable IL-2 was found in the supernatants of A23187-activated pre-effector blasts. However, these cells do express levels of IL-2 mRNA very similar to those of OKT3-activated blasts, from which IL-2 is easily detected in the supernatant. Translational control may account for these findings. A23187-activated CD8+ pre-effector blasts do not respond to stimulation with IFN-gamma nor do they express IFN-gamma mRNA following stimulation with IL-2. These observations suggest that IL-2 may be sufficient to stimulate maturation of these cells. Activation via A23187 results in lower expression of the proto-oncogene c-myb relative to that found in OKT3 activation. C-myb mRNA levels are higher in CD8+ than in CD4+ A23187-activated pre-effector blasts and the c-myb level in the CD8+ pre-effector blasts falls in response to IL-2. This decrease in c-myb mRNA coincides with an increase in proliferation, and the expression of cytolytic activity.
Nelson
P J
PJ
Department of Laboratory Medicine/Pathology and Surgery, University of Minnesota, Minneapolis.
Geller
R L
RL
Bach
F H
FH
D015152:Blotting, Northern; D015704:CD4 Antigens / Q000096:biosynthesis*; D016827:CD8 Antigens / Q000096:biosynthesis*; D000001:Calcimycin / Q000494:pharmacology*; D005455:Fluorescent Antibody Technique; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000502:physiology; D007376:Interleukin-2 / Q000096:biosynthesis; D008213:Lymphocyte Activation / Q000187:drug effects; D016853:Muromonab-CD3 / Q000276:immunology; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis; D012333:RNA, Messenger / Q000032:analysis; D013601:T-Lymphocytes / Q000276:immunology*
D015704:CD4 Antigens; D016827:CD8 Antigens; D007376:Interleukin-2; C000715470:MAS1 protein, human; D016853:Muromonab-CD3; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D000001:Calcimycin; D007371:Interferon-gamma