SELECTIVE EXPRESSION OF BETA-7 INTEGRIN ON LYMPHOCYTES UNDERGOING APOPTOSIS IN LYMPHOID-TISSUES

It has been previously shown that the beta 7 chain of integrin forms h eterodimers with the alpha 4 or alpha E chain, which plays essential r oles in lymphocyte homing to mucosal lymphoid tissues, The aim of this study was to re-evaluate the possible role of the beta 7 integrin oth er than lymphocyte homing, We prepared spleen and lymph node lymphocyt es from biopsied specimens from macaque monkeys and examined for the r eactivity with a monoclonal antibody specific for the beta 7 chain, As a result, a minor population of the lymphocytes with a smaller size, which were in the early stage of apoptosis, was found to express a hig her level of the beta 7 integrin than a majority of the lymphocytes wi th a normal size, Interestingly, the apoptotic lymphocytes expressed n either alpha 4 nor alpha E chains, suggesting that the beta 7 chain on these cells may be associated with an undefined alpha chain, These fi ndings indicate that in the lymphoid tissues the shrunken lymphocytes undergoing apoptosis selectively express a unique beta 7 integrin. (C) 1998 Academic Press.