Search

Repeated exposure of Brown Norway rats to an aerosol of ovalbumin (OVA) induced a state of antigen-specific immunological tolerance, particularly in the IgE isotype. Tolerance was transferable to naive syngeneic animals by inoculation of splenic T cells from tolerant rats. Sequential depletion of tolerant spleen cells by sorting techniques prior to adoptive transfer, employing T-cell subset-specific monoclonal antibodies, indicated that the cells mediating tolerance were CD3+, CD4-, CD5+ and CD8+, but lacked alpha or beta chains in the T-cell receptor (TcR), suggesting that they may be part of the gamma/delta T-cell lineage. Consistent with this suggestion, the sorted population demonstrated considerable enrichment for TcR gamma chain-specific mRNA. As few as 2 x 10(3) cells are sufficient to adoptively transfer tolerance in 200-g adult rats in this model.

The appearance of IgE in supernatant fluids from cultures of human peripheral blood leucocytes (PBL) is employed in many laboratories as an index of antibody 'synthesis'. This study demonstrates that, unlike IgG, the majority of cell associated IgE is sequestered by PBL in a tightly bound form, which resists extraction via the freeze-thawing (F/T) techniques in current use. A method is presented for the quantitative extraction of cell associated IgE, involving brief acid treatment of whole cells, and is shown to yield up to 100% more IgE than the F/T procedure. The use of this extraction process on PBL before and after culture permits discrimination between release of pre-formed IgE and de novo synthesis, both of which are demonstrated to occur to widely differing degrees in PBL cultures from different donors.

The release of serotonin from platelets was examined using polymorphonuclear leucocytes (PMN) from normal volunteers. The stimulating agents emplyed were zymosan and heat-killed bacteria from Enterobacter agglomerans, which is commonly found in cotton dust. Optimal conditions for release were established. Both zymosan and E. agglomerans yielded a release of serotonin of an equal magnitude. The data are discussed in relation to the pathogenesis of respiratory disease associated with occupational exposure to cotton dust.