Monoclonal antibodies OKT 11 and OKT 11A have pan‐T reactivity and block sheep erythrocyte “receptors”

Abstract

Monoclonal antibodies OKT11 (gamma 1) and OKT11A (gamma 2) are described and appear to have similar binding specificities. They bind, in immunofluorescence, with greater than 95% of infant thymocytes, staining both cortical and medullary cells, 65-80% of blood lymphocytes and selectively stain the T cell-dependent paracortical areas of tonsil. A small proportion (9-12%) of bone marrow lymphocytes stain, but this population excludes the terminal transferase-positive cells. Both the gamma 1 and gamma 2 antibodies stain the surface membrane Ig-negative lymphocytes in blood and tonsil and are to block sheep E rosette formation (to normal or leukemic T cells). In contrast, other monoclonal anti-T reagents tested (OKT1, OKT3, OKT4, OKT6, OKT8, OKT9, OKT10) did not block E rosette formation. E rosette formation and OKT11 bindings are coincident on T-ALL cell lines and both are trypsin-sensitive. In a series of 145 leukemias and 26 leukemic cell lines investigated, only leukemias with a T cell phenotype including E rosette positivity were reactive with OKT11 and OKT11A. OKT11A binds to a polypeptide of approximately 50 000 molecular weight on thymic lymphocytes. This structure may carry the recognition site for sheep erythrocytes. These antibodies provide additional useful markers for T cell analysis and are of potential therapeutic value.

Impaired recovery and cytolytic function of CD56+T and non—T cells in systemic lupus erythematosus following in vitro polyclonal T cell stimulation. Studies in unselected patients and monozygotic disease‐discordant twins

“…In some experiments, PBMC were fractionated into E + and E-cell fractions by rosetting with 2-aminoethylisothiouronium bromide-treated sheep erythrocytes (33) and reconstituted at the indicated E+:E-cell ratios. T cells and NK cells both surface express CD2, which binds to sheep erythrocytes (34)(35)(36)(37), so the E + cell fractions predominantly contained T cells and NK cells.…”

Simultaneous increased expression of E‐rosette receptor (CD2, T11) and T cell growth factor receptor on human T lymphocytes during activation

“…The current experiments demonstrated that the expression of the CD2 molecule, i.e., the E-rosette receptor (13,15,17,43), was elevated 10-to 20-fold on human T lymphocytes after activation. The elevation occurred on T cells that were activated either with PHA, which may directly interact with CD2, or with antibody to the CD3-Ti complex (Figs.…”

“…The current data are consistent with earlier findings that the E-rosetting properties of T cells are altered by activation in vitro (10,33,34) andor by certain disease conditions (16) is synthesized in increased amounts on activated T cells, and that this increased amount correlated with the formation of stable E-rosettes. In contrast to other activation antigens that are not detectable on resting T cells, e.g., the TCGF receptor (7,191, the transferrin receptor (7,12,40), or the molecule recognized by the 4F2 antibody (7,11), CD2 is already present on resting cells in readily detectable amounts (13,15,17,43). In spite of this difference between CD2 and Tac expression on freshly isolated T cells, the initial increase in CD2 expression during PHA-stimulated T cell activation occurred at the same time and on the same cells that initially began to express TCGF receptors (Fig.…”

“…PBM from four donors were examined after 3-4-days culture alone or with PHA. There was relatively little increase in CD2 expression beyond that noted by [40][41][42][43][44][45][46][47][48] hr. In some cases, the expression was increased to -20-fold of that noted on resting cells before PHA stimulation.…”

“…The E-rosette receptor (CD2) (13,15,17,43) is a differentiation antigen that occurs on virtually all T cells, whereas CD4 and CD8 identify T cell subsets (31). In addition to these differentiation antigens, there are also activation antigens that are expressed only on stimulated cells.…”