81-0 6-7, [4p-Al )s ____ __ __ __ 4. TITLE (and Subtitle) C. TYPE Or REPpoRr & PERIOa coveEE DO ,~2'IS 473 £01TIO OPI NV 5 ISOUSLIT Unlassaiflied SECURITY CLASSIFICATION OPP THIS PA-3E (When Dae Int.rod) Unclassified -t4CURITY CLASSIPICATION OP ?HIS PAQE("*n beta Sntett) Block 20 --Abstract (continued) 2) Benzo-a-pyrene: (3(C)P when added to LBT assays, caused a concentration related suppression of the LBT response which was not due to cytotoxicity. 3) l,l-dimethylhydrazine: .ost experiments

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... ing the past year involved UDWH. First, mice treated on a short-term basis (9 days) with JDIH were affected similarly to those treated over a 3-month period, i.e., an enhancement of antibody-f-orming cells and no effect on the LBT response. Secondly, in vitro studies with Uf1'-M in the mixed lymphocy-te reaction (MIZ) assay showed that UDMH inhibited the .IM of whole splenocyte populations and of non-adherent splenocyte populations. However, when adherent I splenocy-tes were removed, exposed briefly to UDM, then washed and added back to the non-adherent cells, the : of the reconstituted population was 7enhanced. These experiments indicate that jDY may be interfering with cellular antigen recognition mechanisms between T-cells (responder) and B-cells (stimulator) in the first two experiments, causing a suppressed MR, and between suppressor macrophages (adherent cell) and T-cells in the latter experiment, resulting in an enhanced MLR. Thirdly, preliminary studies of the effects of in vitro UDMR on macr6phage function showed a slight enhancement of phagocytic activity and a significant enhancement of microbicidal activity of UDM-eposed macrophages. -_ o . . .. .. . 10. Unclassified SSECUITY CLASSICATIO11 Of . m&OE(W1ien Oat. 1reterO) I . I Abstract During the past year, the immunotoxic effects of three chemicals were studied: hydrazine (Hz), benzo-q-pyrene (Bk]P), and 1,1-dimethylhydrazine (UDMH). 1) Hydrazine: mice treated with 5-20 mg/kg Hz showed a suppressed antibody-forming cell response after immunization compared to control mice. This immunosuppression correlated with the Hzinduced in vitro suppression of the lymphocyte blast transformation (LBT) response noted previously. 2) Benzo-d-pyrene: B(O)P, when added to LBT assays, caused a concentration related suppression of the LBT response which was not due to cytotoxicity. 3) 1,1dimethylhydrazine: most experiments during the past year involved UDMH. First, mice treated on a short-term basis (9 days) with UDMH were affected similarly to those treated over a 3-month period, i.e., an enhancement of antibody-forming cells and no effect on the LBT response. Secondly, in vitro studies with UDMH in the mixed lymphocyte reaction (MLR) assay showed that UDMH inhibited the MLR of whole splenocyte populations and of non-adherent splenocyte populations. However, when adherent splenocytes were removed, exposed briefly to UDMH, then washed and added back to the non-adherent cells, the MLR of the reconstituted population was enhanced. These experiments indicate that UDMH may be interfering with cellular antigen recognition mechanisms between T-cells (responder) and B-cells (stimulator) in the first two experiments, causing a suppressed MLR, and between suppressor macrophages (adherent cell) and T-cells in the latter experiment, resulting in an enhanced MLR. Thirdly, preliminary studies of the effects of in vitro UDMH on macrophage function showed a slight enhancement of phagocytic activity and a significant enhancement of microbicidal activity of UDMH-exposed macrophages.