Changes and clinical significance of erythrocyte lifespan in megaloblastic anemia / 中华内科杂志

Objective: To investigate the lifespan of erythrocytes in megaloblastic anemia (MA) patients. Methods: A prospective cohort study analysis. Clinical data from 42 MA patients who were newly diagnosed at the Department of Hematology, Lanzhou University Second Hospital from January 2021 to August 2021 were analyzed, as were control data from 24 healthy volunteers acquired during the same period. The carbon monoxide breath test was used to measure erythrocyte lifespan, and correlations between erythrocyte lifespan and laboratory test indexes before and after treatment were calculated. Statistical analysis included the t-test and Pearson correlation. Results: The mean erythrocyte lifespan in the 42 newly diagnosed MA patients was (49.05±41.60) d, which was significantly shorter than that in the healthy control group [(104.13±42.62) d; t=5.13,P=0.001]. In a vitamin B12-deficient subset of MA patients the mean erythrocyte lifespan was (30.09±15.14) d, and in a folic acid-deficient subgroup it was (72.00±51.44) d, and the difference between these two MA subsets was significant (t=3.73, P=0.001). The mean erythrocyte lifespan after MA treatment was (101.28±33.02) d, which differed significantly from that before MA treatment (t=4.72, P=0.001). In MA patients erythrocyte lifespan was positively correlated with hemoglobin concentration (r=0.373), and negatively correlated with total bilirubin level (r=-0.425), indirect bilirubin level (r=-0.431), and lactate dehydrogenase level (r=-0.504) (all P<0.05). Conclusions: Erythrocyte lifespan was shortened in MA patients, and there was a significant difference between a vitamin B12-deficient group and a folic acid-deficient group. After treatment the erythrocyte lifespan can return to normal. Erythrocyte lifespan is expected to become an informative index for the diagnosis and treatment of MA.

Effect of plasmacytoid dendritic cells activited by bacteria on spontaneous remission of leukemia / 中国实验血液学杂志

Spontaneous remission (SR) of leukemia is a rare event in clinic, which possibly correlated with severe infection and sepsis, but its exact mechanism has not been confirmed. Plasmacytoid dendritic cells (pDC) and myeloid dendritic cells (mDC) play a key role in innate and adaptive immunity respectively. A patient with severe infection of staphylococcus aureus acquired completely spontaneous remission (SR), moreover a increased number of pDC were observed, suggesting that bacteria-activated pDC may play an important role in SR. This study was purposed to explore if the bacteria can stimulate pDC successfully and get a functional pDC. Both pDC and mDC were isolated from freshly collected, leukocyte-rich buffy coats from healthy blood donor and leukemic patient with SR by using MACS and FACS. The pDC were cultured in RPMI 1640 medium and were stimulated with different kinds of bacteria and the expression of CD40, CD86 and HLA-DR on the cell surface was analyzed by flow cytometry. The cytokine (IFN-α, IL-12, IFN-γ, IL-2, IL-4, IL-10) production was measured by using ELISA kits. The results showed that the stimulation with staphylococcus aureus and pseudomonas aeruginosa resulted in the maturation of pDC, which secrete a large number of IFN-α and promote the differentiation of naive CD4⁺ T cells to Th1 cells. The activated pDC expressed high level of CD40 and CD86 and showed higher T cell stimulatory capacities. It is concluded that staphylococcus aureus and pseudomonas aeruginosa can activate pDC, the activated pDC secrete high quantity of IFN-α. This result suggests that bacteria stimulated pDC may play a key role in SR of leukemia following severe infections.