After a person is exposed to certain antigens, neutrophils s…

After a person is exposed to certain antigens, neutrophils slow their rolling in blood vessels so that they can leave the vasculature and enter the tissue.  This slowing is mediated by substances produced by endothelial cells lining blood vessels.  Which of the following is the name of these substances?  

Two ml of diluent are placed in each tube in a row of tubes….

Two ml of diluent are placed in each tube in a row of tubes. Two ml of a patient’s serum are placed in the first tube and mixed. Half of the volume is pipetted into the second tube and mixed. Half of the volume is pipetted into the third tube and mixed and so on down the line of tubes. A standard amount of antigen is placed in all tubes and mixed. After a period of time, antigen-antibody reactions can be seen in tubes 1, 2, 3 and 4 but not the remaining tubes. Which of the following most accurately defines the patient’s titer?