T H cells use a T cell receptor to bind antigen presented by MHC molecules on other cells. T H cells respond to cytokines and also release their own cytokines. There are at least two antigen binding sites per Ig molecule. Igs are found on the B cell plasma membrane. The total number of different Ig molecules in an adult human greatly exceeds the total number of genes in a fertilized human egg.
Some infectious microbes can live and reproduce inside macrophages.
Phagocytes use oxidants to help kill bacteria they have engulfed. Phagocytes normally use amoeboid-type motion to move toward microbes. Oscillations in blood pressure due to heart contractions can be measured in veins. The lymphatic system helps defend the body against infection and maintains the volume and protein concentration of the blood. Collagen is found in both cartilage and bone.