| Clue | Source | Date |
|---|---|---|
| Immunity providers | Eugene Sheffer | 13 Mar 2025 |
| Immune response triggers | Universal | 10 Jul 2024 |
| Substances that stimulate the immune system to produce antibodies | Irish Times Simplex | 27 Jan 2022 |
| Substances that stimulate the immune system to produce antibodies | Irish Times Simplex | 26 Aug 2021 |
| Immunologist's isolations | Newsday | 18 Feb 2017 |
| They induce immune system responses | ||
| Foreign instigators? | ||
| Protein stimulants |