Eugene M. Lance

The distribution of chromium 51-labelled lymphoid cells in the mouse: A survey of anatomical compartments

Abstract 51Cr-labeled lymphoid cells derived from lymph node, peripheral blood, spleen, Peyers patches, and thymus migrate distinctively into syngeneic recipients. Each compartment segregates in different ratios into lymph node, spleen, and liver-seeking components. The lymph node-seeking population is believed to represent a pure component of recirculating lymphocytes, while the spleen-seeking population represents recirculating and nonrecirculating cells, as well as hematopoietic precursors. It is proposed that the liver component probably consists of macrophages and dead and dying cells. The functional cell types which these subpopulations may represent is discussed, and quantitive estimations of the size of the recirculating and nonrecirculating compartmental components are made.

INDICATIONS FOR OPEN REDUCTION OF LUNATE AND PERILUNATE DISLOCATIONS OF THE CARPAL BONES.

Au immjury severe enough to cause carpal dislocation usually produces much danmage to the soft parts as well. The treatment chosen should restore the best fimmictioml possible. If necessary, mllOst patients prefer to sacrifice me strength to preserve wrist Illotion, but a weak painful wrist is a real disability. A lIl.llllI)er of surgeons 2.4,6.7.i4,17,i9 advocate open meduction amid our experience 3,5.23 imidicates that this niethod should be selected when closed reductioml does miot restome mmollllal anatonlical relationships between the various carpal bones. After severe, comnphcated, and multiple carpal injuries, normllal mllotion and stremigth canIlot always he iestored hut a good range of painless wrist motion should be obtained. Ill our opinion there are certain definite indications for open operation:

LUNATE AND PERILUNAR DISLOCATIONS

1. A study of fifty patients with dislocations of the lunate bone or perilunar dislocations has been made. The period of observation was adequate in thirty-eight. 2. The injuries generally occur in young or middle-aged men after unusually severe trauma. 3. Associated injuries are frequent, and the most common of these is damage to the median nerve. 4. In one-third of the cases the nature of the lesion was not initially diagnosed or the initial treatment was inadequate. 5. A dislocated lunate bone may be replaced even at a late stage and even if the displacement is severe so long as there is some soft-tissue attachment. The anterior approach may safely be used for the replacement. 6. The lunate bone may be removed without involving the necessity for arthrodesis of the wrist. 7. Open reduction should be employed for trans-scaphoid dislocations whenever exact realignment and good fixation cannot be achieved by closed methods. 8. Excision of the proximal row of the carpus gives the possibility of salvage of a reasonable degree of function, and may be preferable to arthrodesis or removal of only part of the proximal row.

Revascularization and accretion in transplantation. Quantitative studies of the role of the allograft barrier.

The healing of full-thickness iliac bone grafts over a three-month interval was studied in young adult New Zealand white rabbits focusing on the rates of revascularization and new-bone formation. The former was measured by determining the distribution of 51Cr labeled erythrocytes while the latter was estimated from the uptake of 85Sr. Revascularization of autografts proceeded rapidly for four weeks and peaked at six weeks, followed by a slow decline. New-bone formation was maximum at three weeks and remained at a high plateau thereafter. The revascularization of allografts in untreated animals did not show an initial rise and remained significantly lower than autografts after the second week of observation (P less than 0.01). New-bone formation was indolent for the first six weeks (P less than 0.001) and rose slowly thereafter. By contrast, the curves for both factors in allografts of animals treated with azathioprine was virtually superimposable on those of autografts. These studies document and quantitate the barrier imposed on bone implant acceptance by antigenic differences and demonstrate the reversal of this barrier through immunosuppressive treatment.

Transplantation of the rabbit's patella.

A model of transplantation of a joint surface, that is, the patella, was studied in rabbits. The fate of the various components of this composite graft was compared in autografts and homografts in unsensitized and sensitized animals and in homografts in animals treated with an immunosuppressive agent. The effects of immobilization alone were noted and the changes occurring from two weeks to one year were evaluated. In general the articular cartilage fared well regardless of the genetic relationship of host and donor or the immune status of the host. A major technical difficulty lay in faults of healing of the soft tissues leading to joint-surface malalignment which adversely influenced the fate of the transplant. Suggestions are offered to reduce the incidence of this complication but in future applications of the model technical failures should not be included in end-result evaluation. A self-limited but intense soft-tissue infiltration with inflammatory cells occurred in the unmodified homografts. Revascularization of the bone nucleus was also considerably delayed in these animals. Drug-induced immunosuppression favorably affected both the soft-tissue reaction and the rate of revascularization. These findings are discussed in the light of present clinical needs and current knowledge of the immune response to cartilage homografts.

Antigenic change and cell maturation in murine thymocytes

Abstract Changes in the expression of the differentiation antigen TL were studied in a cell-transfer model which segregates thymocytes on the basis of their ability to recirculate. The maturational steps which lead to the acquisition of recirculation are accompanied by a decreased expression of TL suggesting that the loss of this cell surface antigen normally occurs within the thymus prior to emigration to the periphery of “thymus-derived” lymphocytes. However, artificial peripheralization is inimical to the TL phenotype and rapid loss of detectable antigen occurs within 24 hrs. The mechanism underlying this in vivo change is unknown.

Immunoregulation by spleen-seeking thymocytes. II. Role in the response to sheep erythrocytes.

Abstract The plaque cell response to sheep erythrocytes (SRBC) in the draining lymph nodes of lethally irradiated and reconstituted mice was markedly affected by splenectomy shortly after cellular reconstitution. The evidence gathered from different approaches to this model suggest that there exists a subpopulation of cells normally resident in the thymus and spleen but not in the lymph nodes which can suppress the humoral response to this thymus-dependent antigen. Cortisone-resistant cells in the thymus and spleen can mediate this effect and the spleen-seeking segregant of whole thymus is also active. The microenvironment of spleen is required for the expression of this type of regulation. We suggest that there are two entirely separate lines of thymic differentiation; the cell classically identified with cell-mediated immunity, i.e., the long-lived recirculating T cell which preferentially homes to lymph nodes; the second are relatively short-lived cells produced and released in large numbers daily by the thymus, homing selectively to the spleen and involved in the homeostasis of immune responses on the part of the former.

Some observations on the in vitro reactivity of lymphoid subpopulations

Abstract Lymphocytes from the thymus and spleen can be segregated on the basis of their tendency to home to either recipient lymph nodes or recipient spleen. The former respond in vitro better to PHA and in mixed lymphocyte culture than the latter which in turn are more responsive to Concanavalin A. In as much as these functional parameters are specific in T cells these results suggest functional heterogeneity in T cell populations. The population which preferentially responds to Concanavalin A does not appear to be well represented in lymph nodes.

Treatment of Severe Spondylolisthesis with Neural Involvement

Two cases of fourth-degree spondylolisthesis of the fifth lumbar vertebra with cauda equina compression are reported. In the first patient, arthrodesis in the position of deformity failed to relieve neural compression and subsequent decompression by osteoplasty of the sacrum was necessary. In the second patient, partial reduction of the vertebral displacement was achieved by skeletal traction before and after decompression and lateral fusion. It is suggested that reduction and maintenance of reduction in selected cases of severe spondylolisthesis is both desirable and obtainable.

On the mode of action of thymosin

Abstract Thymosin was administered to CBA mice which had been depleted of recirculating small lymphocytes by combining ALS and thymectomy or through lethal irradiation of thymectomised mice reconstituted with syngeneic bone marrow. The population of recirculating small lymphocytes was monitored by determining the numbers of “lymph node localising” cells in the lymphoid organs of treated animals. In no case was there any evidence that thymosin treatment accelerated the recovery of recirculating lymphocytes. Moreover, it was not possible to show that bone marrow cells incubated with thymosin acquired theta-positivity. We conclude that thymosin does not act by augmenting the production of mature recirculating small lymphocytes.