<i>In vitro</i> Lymphocyte Response to Pollen Extract Constituents in Grass Pollen-Sensitive Individuals

Peripheral blood lymphocytes from grass pollen-sensitive patients showed a significant thymidine-2-¹⁴C uptake when cultured <i>in vitro </i>in the presence of a whole mixed grass pollen extract. A depressed lymphocyte response to the same extract in grass-sensitive patients who had received immunotherapy was seen. Dialyzable material of grass pollen extract, showing little or no skin activity, was unable to transform lymphocytes <i>in vitro. </i>A dialyzed extract of <i>Holcus lanatus </i>pollen was then fractionated on DEAE-cellulose and Sephadex G-75. At least four chromatographic fractions were shown to induce a significant <i>in vitro </i>response by lymphocytes from grass-sensitive patients.