RESUMO
The transfer factor is a tiny molecule capable of transferring the function of the T lymphocytes (immunological memory and retarded hypersensitivity) from a sensitized to a non-sensitized individual. The exact structure and action modalities of the molecule have not yet been precisely established. The difficulties involved in the study of the transfer factor are aggravated by the lack of any suitable experimental model. The attention of immunologists is attracted by this factor which opens up new prospects for the treatment of cancer, immunological deficiencies and certain infectious and autoimmune diseases. More profound research would appear useful to evaluate if and in what cases a potentiation of the immune mechanism can represent an alternative to immunosuppression.