IMMUNOLOGICAL ATTRIBUTES OF CYTOKINE MOBILIZED PERIPHERAL-BLOOD STEM-CELLS AND RECOVERY FOLLOWING TRANSPLANTATION

The immunologic attributes of cytokine mobilized peripheral blood stem cell (PSC) products (n = 52) and the resulting reconstitution of the hematopoietic and immunologic system following autologous transplantat ion were examined in a consecutive population of non-Hodgkin lymphoma (NHL), or solid tumor patients at the University of Nebraska Medical C enter. Granulocyte-monocyte colony stimulating factor (GM-CSF)-mobiliz ed PSC products had a high frequency of monocytes (31%) and bands (15% ) as compared to normal peripheral blood (PB) cells. The phenotypic an alysis of the mobilized PSC product revealed that they had normal leve ls of CD4(+) cells, an increased frequency of CD8(+) cells and a corre sponding decrease in the CD4(+):CD8(+) cell ratio as compared to the p eripheral blood leukocytes (PBL) of normal individuals. PSC products a lso had an increase in CD34(+) cells as compared to PB. Natural killer (NK) and T cell activity in the PSC products were also lower than tha t observed in PB. post-transplantation there was an accelerated recons titution of NK-cell function in the PB as compared to T cell function (PHA (phytohemagglutinin) mitogenesis) which did not return to normal by day 100 post-transplantation. We also report for the first time hig h levels of an irradiation resistant suppressor cell activity in the P SC product and in the PB post-transplantation. There was also a concom itant increase in CD4(-), CD8(-), TCR alpha/beta(+) cells (phenotypic homolog of 'natural suppressor' (NS) cells) in the PB post-transplanta tion. The number of months of prior chemotherapy correlated with PHA r esponse but the NS activity and frequency of CD4(-), CD8(-) and TCR al pha/beta(+) cells did not. Further, cytokine mobilization and apheresi s appears to contribute to the loss of PHA responsiveness and the incr eased levels of suppressor cell activity.