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Background Our lab has previously shown that adoptive transfer of in vitro expanded autologous purified polyclonal CD4+ T cells using anti-CD3/CD28 coated beads induced antiviral responses capable of controlling simian immunodeficiency virus (SIV) replication in vivo. Results Expansion on anti-CD3/28 coated beads was found to induce a true polyclonal expansion as CFSE labeled cells uniformly showed dilution of the dye over several days of culture, in contrast to aliquots of the same cells subjected to mitogen stimulation. Of interest was the finding that CD4+ T cells collected before and during early chronic SIV infection or AIDS stage did not show any or only modest differences in proliferative response or expansion kinetics. The reason for such excellent expansion properties was analyzed by the quantitation of telomerase activity in aliquots of expanding CD4+ T cells from sample collected at various times post-infection. First, anti-CD3/28 expanded CD4+ T cells exhibited telomerase levels 2- to 20-fold higher than the starting population of CD4+ T cells. Moreover, while telomerase activity in ex vivo tested CD4+ T cells was found to decrease following SIV infection and disease progression, anti-CD3/28 expansion appeared to restore significant levels of telomerase activity as no difference was noted in telomerase expression between CD4+ T cells expanded from samples collected before or during the chronic SIV infection. When such expanded and CFSE labeled T cells were autologously transferred to monkeys, evidence for extended survival in vivo was provided as CFSE labeled cells were detected to relatively high levels in blood and spleen at 1 week post-infection. Conclusion In summary, the data suggest that anti-CD3/28 mediated expansion of CD4+ T cells retains its immunotherapeutic potential not only during the early stages of lentiviral infection but also at more advanced stages of disease. [ABSTRACT FROM AUTHOR]

Background Our laboratory has previously shown that adoptive transfer of in vitro-expanded autologous purified polyclonal CD4+ T cells using anti-CD3/CD28-coated beads induced antiviral responses capable of controlling SIV replication in vivo. Methods As CD4+ T cells comprise several phenotypic and functional lineages, studies were carried out to optimize the in vitro culture conditions for maximal CD4+ T-cell expansion, survival and delineate the phenotype of these expanded CD4+ T cells to be linked to maximal clinical benefit. Results and Conclusions The results showed that whereas anti-monkey CD3 γ/ ℇ was able to induce T-cell proliferation and expansion in combination with antibodies against multiple co-stimulatory molecules, monkey CD3 ℇ cross reacting antibodies failed to induce proliferation of macaque CD4+ T cells. Among co-stimulatory signals, anti-CD28 stimulation was consistently superior to anti-4-1BB, CD27 or ICOS while the use of anti-CD154 failed to deliver a detectable proliferation signal. Increasing the relative anti-CD28 co-stimulatory signal relative to anti-CD3 provided a modest enhancement of expansion. Additional strategies for optimization included attempts to neutralize free radicals, enhancement of glucose uptake by T cells or addition of T-cell stimulatory cytokines. However, none of these strategies provided any detectable proliferative advantage. Addition of 10 autologous irradiated feeder cells/expanding T cell provided some enhancement of expansion; however, given the high numbers of T cell needed, this approach was deemed impractical and costly, and lower ratios of feeder to expanding T cells failed to provide such benefit. The most critical parameter for efficient expansion of purified CD4+ T cells from multiple monkeys was the optimization of space and culture conditions at culture inception. Finally, anti-CD3/28-expanded CD4+ T cells uniformly exhibited a central memory phenotype, absence of CCR5 expression, marked CXCR4 expression in vitro, low levels of caspase 3 but also of Bcl-2 expression. [ABSTRACT FROM AUTHOR]

Isolated intraepithelial lymphocytes (IEL) and lamina propria lymphocytes (LPL) from jejunum of SIV infected animals were examined for alterations in basal cytokine expression by RT-PCR. Remarkable changes in IFNγ and IL-10 RNA levels were observed in IEL and LPL in SIV infection while IL-4 and IL-2 RNA levels remained unaltered In addition, the CD4+ and CD8+ LPL were examined for intracellular cytokine production following mit0genic activation by flowcytometry, Both CD4+ and CD8+ T lymphocytes in intestinal mucosa retained the potential to produce IFNγ in response to mitogenic stimulation in vitro, without a remarkable change in IL-4 production. The dominant IFNγ cytokine response could be one of the major contributing factors in SIV associated enteropathy. [ABSTRACT FROM AUTHOR]