The Predominant Role of the Spleen in Lymphocyte Recirculation

Abstract

Lymphocyte recirculation through the isolated pig spleen was studied by means of a perfusion system which kept the organ alive for a prolonged period of time. By changing the perfusate to a leucocyte‐enriched or cell‐free perfusate and taking serial arterial and venous samples, the numbers of lymphocytes which homed to or were released from the spleen were measured. In all experiments more lymphocytes homed than were released per minute. There was no apparent difference when autologous or allogeneic cells were used. The number of lymphocytes released depended on the number of lymphocytes homed previously. During the phase of constant release up to 3‐3 × 106 lymphocytes were released per gram spleen per minute. From these values it can be extrapolated that up to 270 × 109 lymphocytes recirculate through the isolated pig spleen per day. Based on kinetic data from other species it is estimated that in the entire pig a total number of 300–400 × 109 lymphocytes recirculate per day. Thus, it can be concluded that the spleen is the most important organ for lymphocyte recirculation in the pig.

Splenectomy of rats selectively reduces lymphocyte function-associated antigen 1 and intercellular adhesion molecule 1 expression on B-cell subsets in blood and lymph nodes

“…However, when lymphocytes were infused into the blood of pigs 5 days after splenectomy a slower disappearance rate was noted. 40 This shows that the effects of splenectomy on lymphocyte entry change over time, which is in agreement with a recent study in rats showing that B lymphocytosis develops from 4 weeks after splenectomy onward and lasts for at least 18 months. 7 Once the B cells are within the tissue, the decreased expression of LFA-1 and ICAM-1 on B cells might weaken their interactions with other cells within the lymph nodes.…”

Migration Pattern of Splenic Lymphocytes after Local Labelling of the Pig Spleen with 3H‐Cytidine

“…In addition, it has been suggested that the lymphocyte recirculation pattern in pig lymph nodes could be different to other species due to a partly different fine structure of the pig lymph node (McFarlin & Binns 1973). Nevertheless, the mean residence time of blood lymphocytes in pigs was comparable to all other species so far studied (Pabst & Trepel 1976) and the spleen seemed to be the predominant organ for lymphocyte recirculation in many species, as discussed in detail previously (Pabst & Trepel 1976). This role of the spleen could be demonstrated by lymphocyte retransfusion studies h intact and splenectomized rats (Whitelaw & Batho 1972) and in more detail in pigs (Pabst & Trepel 1976).…”

Predicted limited redistribution of T cells to secondary lymphoid tissue correlates with increased risk of haematological malignancies in asplenic patients

“…Despite the relatively high retention of cells within the spleen, splenectomy had a negligible effect on tumour lymphocyte recruitment 22 . Another short timescale experiment, with splenectomised pigs, showed that labelled lymphocytes exit the peripheral blood at much slower rate than in non-splenectomised animals 49 . The data collected from isolated perfused pig spleen demonstrated that lymphocytes recirculate through the spleen at a rapid rate of up to lymphocytes per day in living pigs 49 , highlighting the role of the spleen for recirculating T cells.…”

“…The impact of splenectomy on T cell trafficking has so far been addressed experimentally across different species (mice 22 , rats 47 , sheep 48 , pigs 49 ) and across different time periods of observation. Experimental and theoretical distribution profiles of primed T cells from five tissues in tumour-bearing non-splenectomised and splenectomised mice suggested a compartmental shift in lymphocyte distribution following splenectomy 22 .…”