The mouse primed lymphocyte typing (mPLT) test

A murine primed lymphocyte typing (mPLT) assay, based on the sequential selective isolation of specific immunocompetent, alloantigen-reactive T blast cells, has been utilized to define the H-2-associated lymphocyte-stimulating (LS) determinants. Data obtained using mPLT cells indicate that both the Ia molecules of the J region and the SD molecules of theK or D regions possess LS determinants. Isolated Ia molecules as well as isolated SD molecules induce mPLT cell proliferation irrespective of the genetic background, thus revealing that both classes of H-2 LS antigens function in an autonomous manner. Restimulation data of mPLT cells sensitized toI-region gene products indicate that the LS determinants of the Ia molecules are the Ia specificities. However, whereas subregionI-E (I-C) determines one stimulating moiety, ia.7, subregionI-A determines multiple stimulating Ia determinants associated with each allelic product. Genetic analysis, in combination with known serology, suggests that each allelic product of theK andD regions possesses a unique LS determinant. Based on specific cross-reactivities exhibited by mPLT cells sensitized against SD molecules, the recognition of the SD-associated LS determinant appears to be distinct from the recognition of SD specificities by antibody and recognition of the target moiety by cytotoxic T lymphocytes. Thus, this mPLT assay provides a positive approach to defining the H-2 LS determinants as well as a technique for isolating cells with functionally restricted, clonal responses. Furthermore, we propose here a nomenclature for the designation of mPLT-defined LS determinants.