SPONTANEOUS PROLIFERATION OF MEMORY (CD45RO(-)) SUBSETS OF CD4 CELLS AND CD8 CELLS IN HUMAN T-LYMPHOTROPIC VIRUS (HTLV) INFECTION - DISTINCTIVE PATTERNS FOR HTLV-I VERSUS HTLV-II()) AND NAIVE (CD45RO()

Spontaneous lymphocyte proliferation (SLP) in vitro is a characteristi c feature of about 50% of individuals infected with HTLV-I or HTLV-II. Both CD4 cells and CD8 cells contribute to SLP in HTLV-I infection, w hereas SLP in HTLV-II infection is usually restricted to CD8 cells. In this study, we asked if SLP was restricted to the memory (CD45RO(+)) cell subset of CD4 and CD8 cells in HTLV infection. Purified CD4 and C D8 cells were separated into CD45RO(+) and CD45RO(-) populations by a modified panning technique, and spontaneous proliferation (SP) of the cell subsets was assessed. For all five HTLV-I-infected persons whose mononuclear cell cultures were SLP(+), only CD45RO(+) cells, but not C D45RO(-) cells, within CD4 and CD8 subsets showed SP. In contrast, fiv e of six SLP(+) HTLV-II+ individuals showed SP in both the CD45RO(+) a nd the CD45RO(-) subsets of CD4 cells, and 10 of 12 SLP(+) HTLV-II+ in dividuals showed SP of both the CD45RO(+) and CD45RO(-) subsets of CD8 cells. Polymerase chain reaction studies showed that proviral genome was generally present in both CD45RO(+) and CD45RO(-) subsets of CD4 a nd CD8 cells, regardless of HTLV type and SP activity. These findings show that SP of both CD4 and CD8 cells in HTLV-I infection is usually restricted to CD45RO(+) memory cells, whereas in HTLV-II infection, bo th CD45RO(+) memory and CD45RO(-) naive subsets of CD4 and CD8 cells m ay exhibit SP. It thus appears that HTLV-I infection and HTLV-II infec tion exhibit distinctive dysregulatory effects on memory and naive T c ell subpopulations.