Accessory cell presentation of hapten-modified self

Utilization of the hapten-modified self system has increased our understanding of how accessory cells influence immune responsiveness. While the ability to elicit various responses is partially dependent upon accessory cell phenotype, functional differences seem also to be important. By comparing the functional capabilities of purified lymphoid and myeloid accessory cells with tumor cell correlates, we have found that certain hapten-modified cells which express Ia and produce IL 1 are capable of augmenting PFC responses after intravenous administration. These results would suggest that haptenmodified accessory cell carriers which lack Ia or do not deliver secondary signals such as IL 1 (possibly as a result of the haptenation procedure) are responsible for inducing tolerance and suppressor cells. Future work will focus on the mechanism by which P388AD.2 and other tumor cells can elicit augmentation or tolerance in vitro.