QUANTITATIVE ANALYSIS OF IL-2 AND IMMUNOMODULATING EFFECT OF IL-2 ON NK ACTIVITY OF HEPATITIS B PATIENTS

Using125I-UDR labelled K562 cells as target cells, we assay the natural killer cell （NK） activity in peripheral blood mononuclear cells （PBMCs） from 36 cases of various types of viral hepatitis B （HB）, together with 33 healthy adults as controls. At same time the NK activity was detected when PBMCs were pretreated with recombinant IL-2 （rIL-2） in 19 patients with various types of HB and 14 normal controls. We also determined the IL-2 activity produced by PBMCs in 26 HB patients and 14 normal controls. The following results were obtained: （1） The NK activity was markedly elevated in early acute hepatitis B （AH） （P【0.01）; significantly decreased in chronic active hepatitis （CAH）, chronic persistent hepatitis （CPH） and fulminant hepatitis （FH） （P【0.01）, while that of convalescents with AH was within normal range 35.85±12.52%. （2） The early rise of NK activity in acute infection and the decline in convalescence and also the parallel change in SGPT level in 3 AH cases were observed. （3） The amount of IL-2 produced by PBMCs in HB patients was lower than that of normal controls （P【0.01 ）. （4）There was no correlation between the change of IL-2 activity and NK activity in HB patients （r=0.15; P】O.05）. （5） The NK activity of most normal subjects were enhanced when the PBMCs were pretreated with rIL-2 but the latter was still within the normal ranges. These results suggest that the mechanism of the effect of IL-2 in modulating the NK activity of HB patients is very complicated. IL-2 not only directly enhances the low NK activity of HB patients, but also depresses the high NK activity. This immunomodulating effect may be influenced by serum inhibitory facts as well as the amount and the combining ability of IL-2 receptor or on NK cell surface.

Discovery of highly immunogenic spleen-resident FCGR3^(+)CD103^(+)cDC1s differentiated by IL-33-primed ST2^(+)basophils

Recombinant interleukin-33(IL-33)inhibits tumor growth,but the detailed immunological mechanism is still unknown.IL-33-mediated tumor suppression did not occur in Batf3^(−/−)mice,indicating that conventional type 1 dendritic cells(cDC1s)play a key role in IL-33-mediated antitumor immunity.A population of CD103^(+)cDC1s,which were barely detectable in the spleens of normal mice,increased significantly in the spleens of IL-33-treated mice.The newly emerged splenic CD103^(+)cDC1s were distinct from conventional splenic cDC1s based on their spleen residency,robust effector T-cell priming ability,and surface expression of FCGR3.DCs and DC precursors did not express Suppressor of Tumorigenicity 2(ST2).However,recombinant IL-33 induced spleen-resident FCGR3^(+)CD103^(+)cDC1s,which were found to be differentiated from DC precursors by bystander ST2+immune cells.Through immune cell fractionation and depletion assays,we found that IL-33-primed ST2^(+)basophils play a crucial role in the development of FCGR3^(+)CD103^(+)cDC1s by secreting IL-33-driven extrinsic factors.Recombinant GM-CSF also induced the population of CD103^(+)cDC1s,but the population neither expressed FCGR3 nor induced any discernable antitumor immunity.The population of FCGR3^(+)CD103^(+)cDC1s was also generated in vitro culture of Flt3L-mediated bone marrow-derived DCs(FL-BMDCs)when IL-33 was added in a pre-DC stage of culture.FL-BMDCs generated in the presence of IL-33(FL-33-DCs)offered more potent tumor immunotherapy than control Flt3L-BMDCs(FL-DCs).Human monocyte-derived DCs were also more immunogenic when exposed to IL-33-induced factors.Our findings suggest that recombinant IL-33 or an IL-33-mediated DC vaccine could be an attractive protocol for better tumor immunotherapy.