Expression ability of Ia antigens on T cell subsets defined by monoclonal antibodies on pokeweed mitogen stimulation in early human life

Peripheral blood T lymphocytes were purified by 2 cycles of E rosette procedurewith neuraminidase-treated sheep erythrocytes. Less than 5% of T cells either freshly isolated or cultured without pokeweed mitogen (PWM) expressed Ia antigens detectable by indirect immunofluorescence with a monoclonal Okla1 antibody to human Ia antigen framework. The results suggest that Ia antigen expression after PWM stimulation may be restricted to the OKT4 super(+) T cell subset. Although OKT4 super(+) cells in cord blood were able to proliferate in response to PWM like adult OKT4 super(+) cells, neither OKT4 super(+) nor OKT8 super(+) cells in cord blood showed any appreciable expression of Ia antigens on PWM stimulation.