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Inflammation is a physiological event that protects tissues from infection and injury. Chronic inflammation causes immune cell over activation and sustained release of inflammatory cytokines and chemokines cause pathologic conditions including autoimmune diseases. Heavy metals exposure affects innate and adaptive immune systems through triggering inflammatory responses. It seems that extended inflammatory responses could accelerate heavy metal-induced autoimmunity. In the present review we discuss the exposure route and toxicity of Cadmium (Cd), Lead (Pb), Mercury (Hg), Vanadium (V) and Platinum (Pt) and their effects on inflammatory responses by innate and adaptive immune system and autoimmunity.

Plant products provide a vast source of therapeutics, but not without toxicity. This study evaluated the in vitro cytotoxic and proliferative activity of selected plant extracts on human peripheral blood mononuclear cells (PBMCs). The PBMCs from healthy donors were exposed to varying concentrations (25 µg/ml, 50 µg/ml, 100 µg/ml and 200 µg/ml) of aqueous extracts of young leaves of Mangifera indica (MI) and stem barks of Commiphora kerstingii (CK), and Lannea acida and Acacia sieberiana formulation (LAASF). Trypan blue assay was used to determine the viability of human PBMCs after isolation. Cytotoxicity and proliferation of PBMCs were determined using WST-8 assay. The total viable cell count of the isolated PBMCs in this study was 8000 x 104 cells/ml while viability was 96.15%. The extract of LAASF showed the lowest percentage cytotoxicity (2.63%) at 25 µg/ml concentration, followed by CK (2.70%), then MI (7.71%). There was significant decrease in PBMCs mean absorbance scores across the different concentrations of MI (p=0.008), CK (p<0.0001) and LAASF (p=0.01). There was statistically significant proliferation of PBMCs for MI (p=0.003) and CK (p=0.005) compared to control. However, no significant difference was observed in LAASF on proliferation. Mean absorbance scores significantly decreased with an increase in the concentration of the extracts. The extracts have potential cytotoxicity on the PBMCs at higher concentrations. The extract of MI and CK exhibited higher cytotoxic and proliferative activity on the PBMCs than LAASF. An in-depth study to identify specific immune cells proliferated by the extracts will improve the credence of this study’s findings.   Keywords: Herbal medicine, cytotoxicity, cell proliferation, humans, mononuclear leukocytes

A previous study reported on the immunostimulatory activity of a polyherbal formulation (PHF). However, its potential in immunosuppression is unknown. This murine study evaluates the protective activity of aqueous extract of the PHF in cyclophosphamide (CP)-induced immunosuppression. The PHF consists of Acacia polyacantha, Acacia senegal, Adansonia digitata, Allium sativum and Bauhinia rufescens. The study was conducted on 20 rats in four groups: normal saline group, negative control, treatment control group, and experiment group. Delayed type hypersensitivity (DTH) response, keyhole limpet haemocyanin (KLH)-IgG, serum IFN-γ, and IL-4 were measured using digital Vernier calliper and sandwich ELISA, respectively. Histology of liver, thymus, and bone marrow was examined. No significant difference was observed between treatment control and experimental groups in DTH response (p > 0.05). No significant difference prevailed in the mean concentration of KLH-IgG from PHF treatment group to CP treatment group in the experiment (p = 0.48). Also, the serum IFN-γ level in the PHF-treatment group was not statistically different from the CP-treatment group (p = 0.293). The serum level of IL-4 in the PHF-treatment group was also not significantly different from that of the CP-treatment group (p = 0.139). The histology of PHF treated group showed similar features to that of normal and treatment controls. The formulation has demonstrated good protective ability in cyclophosphamide-induced immunosuppressed rats.

Medicinal plants have been widely used for medicinal purposes in the treatment of various ailments including human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS). This study evaluated the effect of aqueous extracts of polyherbal formulation (PHF) on peripheral blood mononuclear cells (PBMCs) of an HIV+ patient. In this study, 4 ml of blood was collected from HIV+ patient who has not commenced antiretroviral treatment. PBMCs were isolated using the Ficoll-Paque method and counted using the trypan blue assay. The isolated PBMCs were treated with different concentrations of the PHF (25 50, 100, and 200 μg/ml). Cytotoxicity and proliferation were determined using the WST-8 assay. The percentage viability in this study was 96.74%, whereas the non-viable cell percentage was 3.26%. The lowest percentage of cytotoxicity for the PHF was 0.05% at 25 µg/ml of the extract, while the highest was 5.35% at 200 µg/ml. The mean absorbance scores of the formulation's various concentrations and the control group did not significantly differ from one another (F=0.622, df = 5, p=0.69). There was significant difference (t= -4.887, df =6, 95% CI= -0.1566 to -0.0521, p = 0.003) in mean absorbance scores between control and treatment. The polyherbal formulation exerts the lowest cytotoxicity of 0.05% and significant proliferation on the PBMCs at 25 µg/ml. The PHF has potential immunoproliferative activity with a good safety margin. An in-depth study of the bioactivity of the PHF on individual immune cells is recommended.