PEER

Establishment and Characterization PEER Cell Line

The PEER cell line exhibited a typical lymphoid morphology. The results of several cytochemical and enzyme tests performed in Israel shortly after the line was established are shown in Table 1. Acid phosphatase had a focal distribution (Fig. 1) which is typical of T-acute lymphoblastic leukemia (ALL).

Table 2 summarizes the results of membrane (cell surface) and intracellular marker tests. PEER cells lack the common ALL antigen and do not express Ia/HLA-DR antigens (two rabbit, one chicken anti-Ia p28, 33 and one murine hybridoma/monoclonal antibody-DA2/anti-HLA-DR "framework") or T-cell antigens (two rabbit and one hybridoma antibody, NA134 which detects a "TL"-like (45K) cortical thymocyte antigen) which are found on most cases of T-ALL and T-ALL cell lines. Positive results were observed with monoclonal antibodies specific for p2 microglobulin (EC3) and HLA-ABC "backbone" determinants (W6/32), monoclonal P17F12 which defines a new T-cell antigen, and a horse anti-human thymus serum which defines a T-cell subset (THZ) with suppressor-cell functions.

Peanut agglutinin (PNA) which is reported to react with immature T cells and T-ALL was also negative although, as on all cells tested, a binding site for PNA could be exposed by neuraminidase treatment of the cells. Both sheep and mouse rosette assays (T- and B-cell markers respectively) were negative as were the EA and EAC tests. Hexosaminidase isoenzyme peak I, which is usually expressed in the common form of ALL but not in T-ALL, was absent, and there was no staining for either cytoplasmic or cell surface Ig.

Fig. 1 PEER cells showing strongly positive para nuclear stain with acid phosphatase. (Ravid Z, et al., 1980)

Table 1. Cytochemical and enzyme tests of the PEER cell line. (Ravid Z, et al., 1980)

Table 2. Cell surface and intracellular marker studies on the PEER cell lines. (Ravid Z, et al., 1980)