This study investigated the immunotoxic potentials of raw and simulated leachates from Olushosun
municipal solid waste landfill in rat using quantitative leucocyte and differential counts. Blood samples of rats
intraperitoneally exposed to 1 – 25 % concentrations of each of the leachate samples for 48 hours were examined
post treatment for leukocyte and differential counts. Compared to the negative control, there was concentration
dependent and statistical significant decrease in leucocyte (P < 0.05) and lymphocyte (P < 0.001) count and
increase in neutrophil count (P < 0.001). There was statistically insignificant decrease in basophil and monocyte
count and increase in eosinophil count. The constituents of the tested leachate samples were believed to
provoke the observed changes in leucocyte and differential count. This finding suggests that municipal solid
waste leachate induced a non-specific immunotoxic effects in rats and may be of public health importance as
there is continuous residential and occupational exposure of human population to hazardous substances from
solid wastes landfill.