Factors leading to the appearance, after BMT, of cytotoxic antibodies against T, B and activated T lymphocytes: critical appraisal.

In order to investigate the role of lymphocytotoxic antibodies, acquired after allogeneic and autologus bone marrow transplantation, we studied 309 sera from 42 transplanted patients (16 adults and 26 children). We tried to correlate antibody elicitation towards T, B and activated T lymphocytes with the following parameters: genetic (recipient's and donor's sex, HLA profile), clinical (recipient's primary disease, GvHD, transplant outcome) and technical (bone marrow purging, auto-or allotransplant). There is evidence that anti-T and -B cytotoxic antibodies appear earlier than anti-activated T antibodies. Anti-HLA specific antibodies seem to be produced by the transfusional stimulus: they appear early after BMT and wane after the first year. Humoral responsiveness seems to be age related (adults are more responsive than children) and conditioned by GvHD (the level of cytotoxic antibodies decreases when GvHD is prevented by bone marrow purging). The level of cytotoxicity is significantly lower in the sera of autotransplanted patients compared with the allotransplanted ones. It appears that anti-activated T antibodies are produced by cell activation at different times in adults and children: in adults this occurs during GVHD and in children during the relapse of disease.