Effect of Thymectomy on Lymphocyte Subpopulations in the Pig

Abstract

Thymectomy in neonatal pigs results in marked lymphopenia. Surface Ig immunofluorescence, Fc rosettes and SRBC rosettes have been used to identify blood lymphocyte subpopulations. There was no marked reduction in numbers of cells in these subpopulations after thymectomy, although their proportion increased. This change was explained by a 90% reduction in ‘null’ lymphocytes, defined as those lacking slg and Dextran SRBC receptor, which comprised 30–45% of blood lymphocytes.

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

“…As these confirm our other published results [2,4,8,9], the only data shown is that included under preseparated (Pre) in table I on nylon wool separation. In all respects studied, these data are typi cal and show that the lymphocyte subpopulation par ameters in the animals studied at this time (1976)(1977) resemble results from our previous and subsequent studies [4,8], Table I and figure 1 confirm and extend, with data on lymphocyte suspensions from 16 pig blood sam ples, our initial characterization of the nylon wool ad herence of pig lymphocyte subpopulations using five pig lymphocyte separations [9], Thus the enrichment and depletion of subpopulations in the non-adherent (NAD) and adherent (AD) fractions (table I) and the calculation of their distribution into the NAD, AD and LOST fractions ( fig. 1 A) show that Null cells are consistently highly non-adherent and slg+ and Fc+ cells predominantly adherent.…”

“…As isolated Null cells are unresponsive and yet, especially those in the NAD fraction, are highly thymus-dependent [6,8], their PHA response was tested in the presence of added macrophages. Initial experiments had shown that added macrophages do not inhibit the PHA re- Figure 2C shows that Null cells (NAD-DS~) were not rendered mature T-1 ike in their PHA response by addition of macro phages ( + M0), nor was the response of NAD-DS+ at optimum greatly enhanced.…”

“…Studies with tuber culin (PPD) responses in vitro were on pigs rendered sensitive, as shown by skin test, by one half ampoule injections (0.5 ml) of BCG (Glaxo Laboratory) subcutaneously at 3 months of age and intra venously 5 and 5'A months later, when vigorous in vitro PPD re sponses were found. Lymphocyte subpopulations were identified using surface markers performed as previously [8]. Studies were made of: slg4 lymphocytes by immunofluorescence, Fc+ lympho cytes by rosette formation with bovine RBC sensitized with hyper immune pig antibody, E rosette-forming lymphocytes by rosette formation with SRBC in dextran (DS*) orsaline (S*) and Null cells using the formula Null% = 100 -(sIg*°/o + DS*%).…”

“…As in other species, pig blood lymphocytes may be broadly divided into 'T and 'B' lineages which are re cognized by a complex of variant surface properties [2,8], Among 'T' subpopulations, there is a major group of lymphocytes which form E-rosettes with sheep red blood cells (SRBC) (-50%) [I, 2] and a large population of lymphocytes (-30%) termed Null cells which lack any recognizable T or B cell surface mark ers [2]. The Null cells are T-like in that they disappear after neonatal thymectomy [8], do not recover in thymectomized pigs after whole body irradiation [6,16], and are the most non-adherent blood lymphocytes for nylon wool [9].…”

“…The Null cells are T-like in that they disappear after neonatal thymectomy [8], do not recover in thymectomized pigs after whole body irradiation [6,16], and are the most non-adherent blood lymphocytes for nylon wool [9].…”