Morula cells as the major immunomodulatory hemocytes in ascidians: Evidences from the colonial species Botryllus schlosseri

Immunocytochemical methods were used to study the presence and distribution of IL-1-alpha- and TNF-alpha -like molecules in the hemocytes of the colon ial ascidian Botryllus schlosseri. Only a few unstimulated hemocytes were p ositive to both the antibodies used. When the hemocytes were stimulated wit h either mannan or phorbol 12-mono-myristate, the phagocytes were not signi ficantly changed in their number, staining intensity, or cell morphology. I n contrast, stimulated morula cells were intensely labeled, indicating that these cells play an important immunomodulatory role.