The immune system defends the body against certain tumor cells and against foreign agents such as fungi, parasites, bacteria, and viruses. One of its main roles is to distinguish endogenous components from non-self-components. An unproperly functioning immune system is prone to primary immune deficiencies caused by either primary immune deficiencies such as genetic defects or secondary immune deficiencies such as physical, chemical, and in some instances, psychological stressors. In the manuscript, we will provide a brief overview of the immune system and immunotoxicology. We will also describe the biochemical mechanisms of immunotoxicants and how to evaluate immunotoxicity.

(1) Background: No goal can be more important than optimal individual quality of life (QOL); life experiences, religious coping, and positivity play pivotal roles in achieving this goal. The aim is to assess the correlation between positive/negative experiences in life and QOL, taking into consideration the moderating role of positivity and positive/negative religious coping among a sample of Lebanese university students. (2) Methods: This cross-sectional study was carried out between November and December 2021, and enrolled 333 university students, aged between 18 and 30 years, from various areas in Lebanon’s governorates. The 12-item Short Form Health Survey, the brief religious coping methods scale, and the Scale of Positive and Negative Experience were included in the questionnaire. Forward linear regressions were conducted to check for correlates associated with physical and mental QOL scores. All variables that showed a correlation or effect size > |0.24| were entered in the multivariable and moderation models as independent ones. Significance was set at a p < 0.05. (3) Results: A linear regression, taking the physical QOL score as the dependent variable, showed that living in rural areas compared to urban and more positivity were significantly associated with a better physical QOL, whereas more negative religious coping was significantly associated with a lower physical QOL. More positivity and more positive religious coping were significantly associated with a better mental QOL. The moderation analysis showed that in people with high positive experiences, those with higher negative religious coping had lower mental QOL. (4) Conclusions: In a society as deeply religious as Lebanon, it is crucial to organize awareness programs to help in discriminating between religious coping mechanisms. Across order to stop further detrimental effects on QOL, our findings may serve as a solid foundation for future studies of QOL with additional variables, in other groups and nations.