To promote equity and diversity among authors reviewers and editors. It contains several different MHC-I and MHC-II genes so that every individual possesses a set. Human Body Immune Systems Powerpoint Chart Powerpoint Charts Human Body Immune System Figure 455 Complement fragment C3d can bind an antigen and then be bound by molecule CD21CR2 on a B cell. . Interestingly though in the decade following the Merchant et al. Biological system that the antigen encounters. Carnes Zorawar Singh Ashar Ata and. Macrophages are versatile cells that reside within tissues and produce an array of chemicals including enzymes complement proteins and cytokines while they can also act as scavengers that rid the body of worn-out cells and other debris and as antigen-presenting cells APC that activate the adaptive immune system. Antigen-presenting cells APC are cells that can process a protein antigen break it into peptides and present it in c...