When incompatible blood is given, antibodies and complement in the recipient plasma attack the antigens on the donor RBC. Hemolysis ensues The antigen-antibody complex activate the Hageman factor (factor XII), which acts on the kinin system to produce bradykinin
Still it is not advisable to take it after the expiry date written on the bottle. This is just for your information to let you know that you are safe. Anyway Saline Nasal spray is not going to do any harm even if you used an expired one. So forget about it.
This is the date at which the manufacturer can still guarantee the full potency and safety of the drug. Most of what is known about drug expiration dates comes from a military-requested study conducted by the Food and Drug Administration (FDA).