Comparison of local and systemic immunity after intratracheal, intraperitoneal, and intravenous immunization of mice exposed to either aerosolized or ingested lead.
The humoral immunity of newborn mice exposed for 28 days to 2.5 mg/m3 aerosolized Pb(NO3)2 (Pb28-aero) or of 2-week-old mice similarly exposed for 14 days (Pb14-aero) was compared with that of both 2-week-old mice given 125 micrograms Pb(NO3)2/day by gastric intubation for 14 days (Pb14-oral) and of 4-week-old nonexposed controls. Mice from each group were immunized with 10(8) sheep red blood cells by intravenous (i.v.), intraperitoneal (ip), or intratracheal (it) routes of immunization. Immunity was assessed by both hemagglutination and the enumeration of antibody-forming cells from the spleen and thoracic lymph nodes. All treatment groups had decreased thymus/body weight and spleen/body weight ratios whereas only Pbaero groups had enlarged livers. The most significant immunosuppression occurred in the ip-immunized Pb28-aero group. A significant suppression of humoral immunity was also observed in thoracic lymph node samples from Pbaero groups immunized it or iv. There was no apparent immunosuppression in any treatment group after iv immunization. These results indicate that aerosolized lead is more immunosuppressive than equivalent amounts of ingested lead. This is most likely due to the greater absorption of inhaled lead and the subsequent cytotoxicity of lead for cells in the draining lymph nodes.
D000818:Animals; D006386:Hemagglutination Tests; D007107:Immune System / Q000187:drug effects*; D007136:Immunoglobulins / Q000032:analysis; D007274:Injections, Intraperitoneal; D007275:Injections, Intravenous; D007854:Lead / Q000008:administration & dosage / Q000633:toxicity*; D007958:Leukocyte Count; D008168:Lung / Q000378:metabolism; D008208:Lymphatic System / Q000378:metabolism; D051379:Mice; D009929:Organ Size; D012119:Respiration; D012756:Sheep; D014018:Tissue Distribution; D014132:Trachea
D007136:Immunoglobulins; D007854:Lead