Factors causing shifts in CD45 fluorescence intensity in flow cytometric leukocyte surface antigen analysis

Abstract

Flow cytometric immunophenotyping of fresh healthy human peripheral blood shows granulocyte (Gr), monocyte, and lymphocyte (Ly) populations in a constant pattern on the CD45/side scatter dot plots. The aim of this study was to evaluate the factors affecting CD45 fluorescence intensity (CD45FI) in Gr and Ly regions shifted from the normal pattern. The subjects were 390 samples from 169 patients for which leukocyte surface antigen analysis was performed during routine testing. First, we examined the correlation between CD45FI in the Gr or Ly region and laboratory data related to inflammation (C-reactive protein, lactate dehydrogenase (LD), neutrophil, lymphocyte, and white blood cell counts). The patients were then divided into groups by diagnosis, and CD45FI was compared between each group and a healthy group. CD45FI was also compared between immunosuppressants-treated, non-treated and healthy groups. The results showed that CD45FI in Gr region correlated with LD and white blood cell counts very weakly, and in Ly region correlated with LD very weakly. Compared to the healthy group, CD45FI in the Gr region was significantly lower in autoimmune disease group (p < 0.001) and congenital immunodeficiency group (p < 0.05), and that in Ly region was significantly lower in the autoimmune disease group (p < 0.01) and fever of unknown origin group (p < 0.01). CD45FI in both regions was significantly lower in the immunosuppressant-treated group than in the non-treated group (p < 0.0001) and the healthy group (p < 0.01). This study suggests that one of the factors affecting CD45FI in both regions is the involvement of immunosuppressive conditions, including with immunosuppressant therapy.