Subpopulations of pig blood E-rosette-forming lymphocytes and thymus-dependent null cells: separation by nylon wool columns, rosette formation and macrophage-dependent mitogen and antigen responsiveness.

Pig peripheral blood lymphocyte subpopulations were characterized by their adherence to nylon wool. Thus whilst B cells, defined by surface Ig and Fc receptor, were predominantly adherent, thymus-dependent Null cells and the T cells forming rosettes with sheep red blood cells in dextran (DS+) were predominantly non-adherent. There was a direct relationship between the size of the non-adherent fraction and the proportion of the total DS+ cells which were in the non-adherent fraction. Using nylon wool and/or DS rosette separation, lymphocytes from normal and BCG sensitized animals were stimulated in vitro with phytohemagglutinin (PHA), concanavalin A (Con A) and tuberculin (PPD). The cells responding to PHA and Con A (T cell mitogens in other species) were DS+ lymphocytes. Non-rosetting, adherent (B cells) and non-adherent (thymus dependent Null cells) lymphocytes were unresponsive, even in the presence of homologous alveolar macrophages at levels which greatly enhanced the PPD response. Cells responding to PPD were present in the DS+ and DS-, adherent and non-adherent fractions but their response was apparently controlled by macrophage dependence and suppression. Techniques are described for the preparation and storage in liquid nitrogen of alveolar macrophages resulting in high numbers of viable cells, capable of helping in vitro responses, even after 3 years of storage.