ALLOREACTIVE LYMPHOKINE-ACTIVATED KILLER-CELLS FROM ATHYMIC NUDE RATS DO NOT EXPRESS CD3-ASSOCIATED ALPHA BETA OR GAMMA DELTA T-CELL RECEPTORS

Lymphokine activated killer (LAK) cells from athymic nude rats, previously shown to selectively kill MHC-incompatible small lymphocytes in vitro, were examined for rearrangement and expression of genes for the T cell antigen receptors. Southern blots showed no rearrangement of the TCR β-chain genes, and Northern blots showed transcription only of truncated 1.0 kb β-chain messages, but not of full-length, 1.3 kb β-chain mRNA. Transcription of the a-chain of the TCR could not be detected, and surface staining with the mAb R73 showed no expression of the rat TCR α/β heterodimer. Transcripts hybridizing with a rat TCR Cγ probe were detected on Northern blots, but probes for all presently characterized mouse Vγ genes failed to hybridize to the same filters, indicating that the Cγ-containing transcripts probably were from non-rearranged genes. CD3 δ and εchain transcripts could not be detected by Northern blot analysis. Less than 2% of the cells stained with the anti-rat CD3 monoclonal antibody 1F4, and incubation with IF4 had no effect on the alloreactivity of nude rat LAK cells. We have previously shown that immunoglobulin is not involved in the killing of the allogeneic lymphocytes. The most likely interpretation of these results is therefore that nude rat LAK cells express a novel receptor structure involved in allorecognition. © 1990 Oxford University Press.