Antibodies to human T lymphocytes in xenoantisera elicited with a new immature T-cell line (Peer)

Peer, a continuous line of immature T lymphocytes, was recently established from a patient with T-cell leukemia. In the present study antisera elicited in rabbits by immunization with Peer cells and absorbed with B cells were found to react with a distinct T-lymphocyte antigen. Absorbed anti-Peer serum was highly cytotoxic for human thymus cells and exerted a preferential activity on peripheral T lymphocytes. Peripheral blood lymphocytes (PBL) surviving exposure to anti-Peer serum and complement were depleted of most of the cells forming E rosettes, whereas the proportion of cells forming EAC' rosettes was increased. Similarly, the depletion of cells forming E rosettes resulted in a concomitant reduction of the sensitivity of PBL to the cytotoxic effect of anti-Peer serum, while the enrichment of E-rosette forming cells had the opposite effect. Anti-Peer serum did not inhibit the formation of E rosettes by PBL in the absence of complement. Absorbed anti-Peer serum failed to exert any cytotoxic effect not only on normal B lymphocytes but also on the CBL and IMB B-cell lines, yet maintained a cytotoxic activity on the Raji and Daudi cell lines. A possible interpretation of these results is that immunization with Peer cells, a line of immature T lymphocytes, leads to the production of antibodies to a distinct antigen expressed on thymus and peripheral T cells. The antigen seems to be absent from normal peripheral B lymphocytes, but may be expressed on a line of pre-B cells, such as the Raji and Daudi lines.