B‐ and T‐Lymphocyte Subset Numbers in the Migrating Lymphocyte Pool of the Rat: the Influence of Interferon‐γ on its Mobilization Monitored through Blood and Lymph

Abstract

The subset composition of the migrating lymphocyte pool is largely unknown. In order to determine the number of B, T, CD8+, CD4+ and CD4+ 'naive' (CD45RC+) and 'memory' (CD45RC-) lymphocytes in this pool, the thoracic duct lymph of the rat was drained for 7 days. The effect of lymphocyte depletion on the number of blood lymphocytes was also monitored. In addition, the influence of continuously applied interferon-gamma (IFN-gamma) on the mobilization of the migrating lymphocyte pool was investigated. Within 1 week 2 x 10(9) thoracic duct lymphocytes (TDL) were collected, which represents about 50% of the total lymphocyte pool of an adult rat. Among the migrating lymphocytes an early and a late mobilized population could be differentiated. In the former the CD4+ 'naive' (CD45RC+) T lymphocytes constituted the largest population, whereas in the latter it was the B lymphocytes. Continuous infusion of IFN-gamma did not affect the number of lymphocytes in the blood. In contrast, in the thoracic duct IFN-gamma reduced the appearance of all lymphocyte subsets. However, the pattern of reduction over time differed markedly depending on the population (early or late mobilized) and the phenotype (B- or T-lymphocyte subsets). Thus, the migrating lymphocyte pool of the rat is very heterogeneous regarding its populations and shows complex changes in the mobilization pattern after IFN-gamma stimulation. Future studies should focus on how the size and the composition of the migrating lymphocyte pool is regulated.

The migratory behavior of murine CD4+ cells of memory phenotype

“…These cells were detected within HEV and appeared in efferent lymph a short time after i.v. injection [4]. In mice, low or high expression of the CD45RB exon detected by mAb 23G2 and, in some strains, high and low levels of the CD44 molecule (standard form) separate memory from naive cells, respectively [5].…”

B and T lymphocyte subsets enter peripheral lymph nodes and Peyer's patches without preference in vivo: no correlation occurs between their localization in different types of high endothelial venules and the expression of CD44, VLA‐4, LFA‐1, ICAM‐1, CD2 or L‐selectin

“…In conclusion, it is possible to define distinct populations among blood lymphocytes by examining the expression of various adhesion molecules. However, proposed homing properties based on such determinations remain hypothetical unless confirmed in vivo [30]. …”

“…After centrifugation (10 min, 400 X g) the pellet was resuspended and about 1 X lo6 lymphocytes were incubated with mouse anti-rat monoclonal antibodies to characterize CD44 (0x49, IgG2a, [14]),VLA-4 (HP2/1, IgGl, against human VLA-4, but cross-reactive with rat VLA-4 [ 151 , Dianova, Hamburg, Germany) , LFA-1 (WT1, IgG2a, [16]), ICAM-l(lA29, IgG1, [17]) and CD2 (0x34, IgG2a, [MI). A PE-conjugated monoclonal antibody was used as second-step antibody, as described previously [19]. After washing, staining for the following lymphocyte subsets was performed using FITC-conjugated antibodies [19]: B lymphocytes ( x light chain+, Ox12),T lymphocytes (ap Tcell receptor+, R73), CD4+ (W3/25) and CD8+ (0x8).…”

“…A PE-conjugated monoclonal antibody was used as second-step antibody, as described previously [19]. After washing, staining for the following lymphocyte subsets was performed using FITC-conjugated antibodies [19]: B lymphocytes ( x light chain+, Ox12),T lymphocytes (ap Tcell receptor+, R73), CD4+ (W3/25) and CD8+ (0x8). Isotype-matched, irrelevant antibodies served as controls.…”

An application of linear output error modelling for studying lymphocyte migration in peripheral lymphoid tissues

“…However, this technique can only provide information about the central lymphatic system that is relatively uninformative in relation to lymphocyte migration through lymphoid tissues. Furthermore, there are indications that thoracic duct drainage is likely to distort the pattern of lymphocyte migration observed in the thoracic duct, because of rapid depletion of the lymphocyte pool occurring even as early as 24 hours after cannulation 7 . In contrast, peripheral lymphatic cannulation (such as that involving the efferent vessel from a lymph node) can be undertaken in large animals (ie sheep) and so allow direct observation of lymphocyte migration through peripheral lymphoid tissue under physiological conditions 8,9 without the risk of depleting the recirculating lymphocyte pool.…”