COMPARTMENTS WITHIN THE LYMPH-NODE CORTEX OF CALVES AND ADULT CATTLE DIFFER IN THE DISTRIBUTION OF LEUKOCYTE POPULATIONS - AN IMMUNOHISTOCHEMICAL STUDY USING COMPUTER-ASSISTED MORPHOMETRIC ANALYSIS

The combination of an immunohistochemical technique and a panel of mon oclonal antibodies was used to investigate the presence of leukocyte p opulations in the distal jejunal lymph node of 3-4 week old calves and adult cattle. The application of computer-assisted morphometric analy sis enabled information to be obtained on the distribution of leukocyt e populations in lymphoid compartments of the lymph node cortex. Semi- quantitative estimates of the areas of staining in histological sectio ns showed that calves possessed significantly fewer B-cells and CD4+ c ells in the outer cortex and significantly fewer T-cells (CD4+, CD8+ a nd gamma delta T-cells) in the deep cortex. These findings were interp reted to be a possible consequence of immunosuppression resulting from the passive transfer of maternal immunity in colostrum, The presence of some B-cell follicles in the region defined as the deep cortex sugg ested the on-going differentiation of this predominantly T-cell compar tment, The larger presence of interdigitating cells (IDC) in the deep cortex of calves than adults was suggested by significantly larger CD1 + populations and it was argued that this could be the result of the c onfrontation with exogenous antigen faced by calves in early postnatal life. Antigen presenting populations, pan MHC II+ and MHC II DQ+ popu lations, were increased in all compartments of calf lymph nodes but we re not significantly different from the populations in adult lymph nod es. Variance component analysis of the data generated in the present s tudy shelved that the image analysis technique was an effective and st atistically powerful approach to investigate Leukocyte populations wit hin the specific microenvironments of the lymph node. (C) 1998 Publish ed by Elsevier Science Ltd. All rights reserved.