Rabbit antisera to human cord Tγ cells

Abstract

T cells with Fc receptors for IgG (Tγ) were isolated by ox cell EA rosetting from 50 human cord bloods. Non-Tγ cells (Tμ and T null) were collected at the same time and frozen live in liquid nitrogen. Antisera produced in rabbits by three or four weekly intravenous injections of cord blood Tγ cells were inactivated at 56°C and extensively absorbed with sheep and ox erythrocytes, B-cell lines, suspensions of fresh human thymus (largely T null), and finally non-Tγ cells from original cord bloods. Absorbed anti-Tγ reagents used as F(ab)′ 2 fragments to avoid inadvertent Fc receptor binding were studied by indirect immunofluorescence with FITC goat anti-rabbit F(ab)′ 2. F(ab)′ 2 anti-Tγ antisera stained 5–14% of T cells and 50–66% Tγ cells. No significant staining was noted with monocytes, macrophages, B cells, or non-Tγ T cells. Absorbed anti-Tγ reagents showed no residual anti-human Ia-like specificity, however, double immunofluorescence staining for human Ia-like antigen positive T cells and cells staining with anti-Tγ reagents showed a 50% overlap. An average of 32.5% Tγ cells showed antigens staining with OKM1, a hybridoma identifying antigens related to monocytes; however, only 18.5% of Tγ cells showed double staining with OKM1 and F(ab)′ 2 anti-Tγ antisera. These findings emphasize possible broad heterogeneity within the human Tγ cell subpopulation.