Human T lymphocyte receptor for sheep erythrocytes: Characterization of a specific antiserum and its application in the detection and quantitation of the receptor in a soluble form

An anti-human T lymphocyte serum specific to the receptor for sheep erythrocytes (E) was produced by immunizing sheep with the complex autologous E-soluble E receptor (ER s). The soluble receptor (R s) was obtained by heating human lymphocytes at 45 °C for 1 hr. The anti-R s serum has been shown to inhibit E-rosette formation, to be cytotoxic to T cells, to identify T lymphocytes by indirect immunofluorescence, and to stimulate blastogenesis. The reaction of anti-R s with R s was directly demonstrated by two newly developed methods: agglutination of complexes formed by the treatment of formolized E with R s (EFR s complexes) and adhesion of a protein A producer strain of Staphylococcus aureus to EFR s treated with anti-R s. The anti-R s antibodies could be neutralized by R s present in supernatant of heated peripheral lymphocytes, inhibiting the above reactions and therefore providing methods to quantitate R s in biological preparations. The importance of these assays is that R s plays an immunoregulatory activity, and high levels of R s in serum are associated with depressed cell-mediated immunity.