No description available.

No description available.

Graduation date: 1996

A bacterial challenge assay was developed utilizing the earthworm, Lumbricus terrestris, in order to assess potential immunotoxic effects from exposure to specific polychlorinated biphenyl congeners. Earthworms were inoculated with Aeromonous hydrophila, establishing a 10-day LD50. In vitro assays for effects of PCBs on phagocytosis agreed with mammalian studies, demonstrating potent suppression of phagocytosis by the non-coplanar PCB congener 138 and no suppression by the coplanar congener 126. However, when the effects of the two PCB congeners were evaluated for suppression of resistance to a whole animal infection challenge assay, coplanar PCB 126 decreased the ability of L. terrestris to withstand infection while non-coplanar PCB 138 did not.

Objectives were to: (1) assess toxicity of polychlorinated biphenyls on Eisenia foetida, in terms of survival (LC5O/LD5O), and suppression of coelomocytes to form secretory (SR) and erythrocyte rosettes (ER) with, and to phagocytize rabbit erythrocytes; and (2) compare results with those of Lumbricus terrestris to assess relative sensitivities to PCB. Using 5-d filter paper contact exposure protocol, LC50 and LD50 were 30.4 cg/cm2 and 4450 cg/g dry mass, respectively. Nominal PCB exposure concentrations of 5.0 and 10.0 pg/cm2 resulted in tissue levels of 1389 and 2895 pg/g dry mass causing a significant reduction in SR formation by 18 and 52%, respectively. ER formation and phagocytosis were reduced significantly (52 and 61%) only at the higher tissue concentration. Compared to reported data on lethality and immunomodulation in L. terrestris, E. foetida appears to be more resistant.

This research is part of an effort to develop non-mammalian surrogate immunoessays with the earth worm Lumbricus terrestris to assess immunotoxic potential of xenobiotics to mammals. The objective was to determine if earthworm immunoessays, namely E- and S- rosette formation and phagocytosis, are sensitive to a known mammalian immunotoxin, the PCB Arclor 1254. Results are presented in terms of PCB exposure and tissue concentrations during uptake/depuration.