Impact of chemotherapy on lymphocytes and serological memory in recovered COVID-19 patients with acute leukemia

Chemotherapy is the major method of treatment for acute leukemia to date, while intensive chemotherapy may impair immunity. We previously reported that leukemia patients were more susceptible to COVID-19 than the overall population. However, for COVID-19 recovered patients with leukemia, the impacts of intensive chemotherapy on the immune memory of COVID-19 are unknown. This study characterized the changes in immune cells and SARS-CoV-2 antibodies in acute leukemia patients, who underwent chemotherapy after recovering from COVID-19. The study enrolled three groups of individuals. One group was a total of three acute leukemia patients, who recovered well from COVID-19 before the last cycle of chemotherapy. The other two groups were six COVID-19 recovered healthy people, and six normal uninfected healthy people, respectively. Levels of B cells, T cells, and NK cells in peripheral blood were analyzed by multiparameter flow cytometry. Besides, the SARS-CoV-2 antibodies were monitored. The results showed that B cells were severely decreased after chemotherapy, especially memory B cells. Most of the T cells and NK cells showed only minor changes after chemotherapy, except for γδ T cells. The serum levels of SARS-CoV-2 antibodies were not significantly affected after chemotherapy in two leukemia patients. However, interestingly, one leukemia patient's SARS-CoV-2 IgM showed dramatically increase, suggesting possible loss of serological memory after chemotherapy. These findings raised the concern for the stability of immune memory against SARS-CoV-2 during chemotherapy and the choice of anti-leukemia treatment in the COVID-19 pandemic.