I just saw what you said about what the doctor said. I’m going to guess he just did very basic routine tests, people above have already named most of them.
Hormones, especially thyroid. The test would be called TSH in English. Also a CBC, which is the red blood cells, platelets, white count, etc. Another might be the CMP which is electrolytes and some others.
If he was checking for a specific illness he might have ordered tests for autoimmune disease, but then that would likely be 6 viles of blood taken in total.
He may have checked for cholesterol/lipids, but that would not be a test associated with immunity.
Look at your lab results, do not rely just on your doctor to interpret them. If he did not test you for Vitamin D I highly recommend it, especially if you live in Germany.