Light and electron microscopic study on the effect of bradykinin potentiating factor (BPF) on immune-suppressed malathion juvenile male rats

Background :Malathion is an organophosphorous insecticide that is widely used and causes major pollution. It has been found to modify the normal function of many systems, especially the immune system of humans and other wild life species. Recently, it has been classified as an immunotoxicant chemical. Objective :To determine the effects of malathion on the bone marrow and spleen, as a part of the immune system, and to determine whether bradykinin potentiating factor (BPF) was able to counteract these effects. Materials and methods :Fifty-four juvenile rats were divided into three groups: the control group, wherein the animals received saline vehicle, the malathion group, wherein the animals were treated with malathion, and the BPF group, wherein the animals received BPF after malathion. The malathion group included three subgroups A, B, and C s acrificed after 2, 4, and 6 weeks of malathion exposure, respectively. The BPF group was exposed to malathion as in malathion subgroups; then, every subgroup was treated with single, double, and triple successive injections of BPF, respectively. After scarification, the bone marrow was aspirated using a sterilized syringe from the femur and immediately processed for light and electron microscopic study. Spleen specimens from all animals were also processed for histological and electron microscopic examination. Immunological parameters, proinflammatory markers, total antioxidant capacity, oxidative stress index, and acetylcholine activity were determined. Results :Bone marrow specimens of the malathion subgroups showed marked degenerative changes in most blood elements. However, the white pulp of the spleen in the first subgroup of malathion-treated rats showed expansion of the lymphatic nodule associated with the frequent appearance of germinal centers. However, in the second and third subgroups of malathion exposure, depletion of lymphocytes from the periarterial lymphatic sheath as evidenced in H E sections was observed. A significant decrease in the immunological parameters and antioxidants along with an increase in the proinflammatory markers was observed. Supplementation with BPF, especially the double and triple successive injections, led to a significant improvement in malathion-induced immunotoxicity as evidenced by the recovery of the bone marrow and preservation of the lymphocytic content of the white pulp of the spleen. T he physiological results were consistent with these findings, where normalization of peripheral blood elements and a reduction in the elevated proinflammatory markers were observed after an injection of BPF. Conclusion:Malathion exerted an immune toxic effect that mediated directly on the bone marrow and spleen, and indirectly through alteration of cytokines and antioxidants. BPF can reduce the malathion toxicity of these organs considerably.