Reply: Some afterthoughts - Pragmatic and philosophical

Conditions under which one searches for Fc-signalling determine the success in finding it. A major condition is that one must have enough T cells to drive a T-cell-dependent response, but not enough T-cell activity to obscure the Fc-signalling. Antigen-masking and destructive phagocytosis of antigen occur. Under conditions and in areas of the body where T-cell activities are limiting and Fc-signalling can not be blocked, Fc-signalling may be observed. The balance between costimulation and coinhibition is a major determinant in immune responsiveness, because costimulation and coinhibition interfere with each other.