The primary function of the immune system is surveillance over mutated, damaged, and old cells that can lead to the development of cancer and autoimmune diseases.¹

Immune responses can be classified into two categories: the innate (natural; non-specific) and the adaptive (acquired; specific) immune response.²

The innate immune response involves neutrophil, eosinophil and basophil granulocytes, mast cells, dendritic cells, monocytes and macrophages, and natural killer (NK) cells. Their functions include phagocytosis, release of inflammatory mediators, cytokine production, and antigen presentation.²

The adaptive immune response involves the immunoglobulin (Ig)/antibody-producing and secreting B cells as plasma cells, and T cells including CD4+ T helper cells and CD8+ cytotoxic T cells.²
Innate immunity provides the first reaction of the immune response, while adaptive immune responses require more time for the activation of various lymphocyte subpopulations.²

The figure shows the timeline during innate (non-specific) and adaptive immune responses (specific).

Bibliography

1. D. Skrajnowska and B. Bobrowska-Korczak. Nutrients 2019, 11, 2273
2. Peterfalvi, A. et al. Molecules 2019, 24, 4530