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 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.

Establishment and characterization of a new leukaemic T-cell line (Peer) with an unusual phenotype.

We report the isolation and establishment in continuous culture of a human lymphoid cell line (Peer) from a case of T-leukemia. The Peer cell line lacks some typical cell-surface properties of T cells, namely sheep erythrocyte rosette formation and reactivity with two anti-T-cell sera, but has focal acid phosphatase and does express two other T-cell antigens, one defined by a monoclonal antibody, the other related to a T-cell subset (TH2). The cells are negative for B-cell markers (SmIg or cytoplasmic mu Fcgamma and C3 receptors, mouse erythrocyte rosettes) and EBV (EBNA). In addition, the Peer cell does not possess the typical phenotypic markers of "non-B, non-T" leukemia: cALL and Ia-like antigens, and the cytoplasmic hexosaminidase isoenzyme I, but is positive for terminal deoxynucleotidyl transferase by enzymatic and immunofluorescent criteria. The cell line requires exogenous L-asparagine for adequate growth in culture, a property known to be characteristic of certain T cells but not of B cells. The Peer cell line appears to have a maturation arrest at a developmental stage intermediate between the cortical thymocyte and a mature T-cell subset and to have lost some T-cell differentiation features.