On immunological memory

Immunological memory may not represent a special characteristic of lymphocy tes but simply reflect low-level responses driven by antigen that is re-enc ountered or persists within the host. T-cell memory is important to control persistent infections within the individual host and cannot be transmitted to offspring because of MHC polymorphism and MHC-restricted T-cell recogni tion. In contrast, antibody memory is transmissible from mother to offsprin g and may function essentially to protect offspring during the phase of phy siological immune-incompetence before, at and shortly after birth. This phy siological immune-incompetence is a result of MHC polymorphism and the dang ers of the graft-versus-host and host-versus-graft reaction between mother and embryo, which necessitate immunosuppression of the mother and immune-in competence of the offspring. One may argue therefore that immunological mem ory of transmissible immunological experience is the basis on which MHC-res tricted T-cell recognition could develop or coevolve.