Constancy of cross reactivity patterns during the anti-HL-A response.

Three immunizations yielding cross reacting anti-HL-A antibodies were followed for 1 year or more. The specificities of the antisera obtained at different times were determined from their reactivity against a selected cell panel. Each antiserum was titrated against cells presenting different degrees of cross reaction. An extensive absorption study of each antiserum, diluted to one cytotoxic unit, was also performed. The data obtained suggest that the cross reactivity pattern in each response is rather rigidly established from the beginning and that it has little chance to vary even after secondary stimulation from the same donor.