Effects of dichlorvos on lymphocyte reactivity during pregnancy in the pig.

This experiment was performed utilizing a total of 21 primiparous crossbred sows to determine whether a state of immunological suppression occurs during the latter stages of pregnancy in the pig and whether dichlorvos treatment affects immunological function of sows. Immunological reactivity was monitored by the use of in vitro lymphocyte transformation experiments employing the mitogens phytohemagglutinin (PHA), concanavalin A (Con A), pokeweed mitogen (PWM) and lipopolysaccharide (LPS). The degree of blastogenesis of lymphocytes recovered from animals on this experiment was not affected by dichlorvos treatment. Blastogenesis was not affected by stage of pregnancy except in the case of that induced by LPS, which decreased (P less than .05) with advancing pregnancy. Sera from animals in this experiment were tested in a PHA-induced lymphocyte transformation experiment and it was found that sera from control animals were not inhibitory at any time. On the other hand, sera from dichlorvos-treated sows inhibited (P less than .01) PHA-induced blastogenesis. The possibility exists that dichlorvos may increase fetal survival by inhibiting the ability of the sow to immunologically damage the fetus.