EFFECTS OF AGING ON THE DYNAMICS OF LYMPHOCYTE ORGAN DISTRIBUTION IN MICE - USE OF A RADIOIODINATED CELL-MEMBRANE PROBE

We have employed a derivatized aminostyrylpyridinium dye, [I-125]I2P-D i-6-ASP, to provide a relatively stable tag on mixed mouse splenocytes and purified B and T cells for the purpose of tracking the distributi on of those cells among the organs of normal young (4 months) and aged (> 26 months) recipient mice. Cells from both young and aged donor sp leens were studied. Special emphasis was placed on localization of don or cells in the spleens of the recipients because the majority of circ ulating lymphocytes localize in the spleen and the spleen is the princ ipal organ of primary immune response. There was a profound difference in the efficiency of splenic acquisition of donor cells between young and aged recipients, a difference not found in the liver, lungs, kidn eys or heart. In contrast young and old donor lymphocytes lodged equal ly well in the spleens of recipients of the same age. It was clear tha t the competence of the splenic microenvironment to serve as a lodging site for circulating lymphocytes deteriorated with age. Such a change could contribute significantly to the deficient immune response of ag ed subjects. We suggest that aging results in significant change in th e splenic extracellular matrix to serve as an adhesive substratum for lymphocytes. Our data point to a need for detailed studies on age-rela ted changes in components of the extracellular matrix within lymphoid tissues. The novel compound which we employed for cell labeling is bot h radioactive and fluorescent and should be quite suitable for such st udies. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.