The selective adherence of lymphoblasts to antigenic cell monolayers. A method for determining the specificity of lymphocytes proliferating in response to histocompatibility antigens.

The specificity and intensity of the immune response of rat lymph nodes draining a skin allograft were examined by exploiting a monolayer of donor-type thoracic duct lymphocytes as an immunoabsorbent. Stable monolayers were produced by attaching lymphocytes from different strains of rat to Petri dishes pretreated with poly-L-lysine. The responding lymph node cells were labelled in vitro with [3H]Thymidine, incubated on the monolayer and mechanically separated into non-adherent and adherent fractions. The radioactivity associated with the adherent fraction was 7--8 times greater when the monolayer displayed the immunizing major histocompatibility antigens than when syngeneic or 'third party' monolayers were used. The non-specific adherence to syngeneic monolayers was low and consistent. Immunization to minor histocompatibility antigens may also be studied by this method.