The number of circulating natural killer (NK) cells is associated with response to rituximab treatment in patients with immune thrombocytopenia (ITP), according to a new study published in the British Journal of Haematology

This finding can help predict the response to rituximab treatment among patients with ITP and help clinicians choose the best treatment option for their patients, the researchers noted.

Read more about the treatment of ITP

Rituximab can be beneficial in the second-line treatment of some patients with ITP, they added. 

To identify factors that can predict the response to rituximab treatment in these patients, a team of researchers led by Jean-François Viallard, MD, PhD, from the University Hospital Centre of Bordeaux, in Pessac, France retrospectively analyzed the clinical course, biological markers, and the number of blood lymphocyte subsets in 72 patients with ITP being treated with rituximab between 2007 and 2021.

The team divided the patients into 3 groups according to the platelet count at 6  months: those who exhibited a complete response, those with a partial response, and those with no response.

They found that a low number of CD3−, CD16+, and CD56+ circulating NK cells was associated with a complete response to rituximab. 

Moreover, rituximab therapy led to complete responders having a higher percentage of NK cells and a lower percentage of activated CD8+ T cells.

“These results emphasize that the role played by NK cells in ITP remains incompletely known,” the researchers concluded, “but that factors predictive of response to rituximab can be easily derived using blood lymphocyte subset data.”

Rituximab is an antiCD20 antibody that was first approved by the US Food and Drug Administration in 1997. It can be used to treat CD20-positive B-cell nonHodgkin’s lymphoma, chronic lymphocytic leukemia, rheumatoid arthritis, microscopic polyangiitis and granulomatosis with polyangiitis, and pemphigus vulgaris.


Rivière E, Thiébaut R, Lazaro E, et al. Assessment of circulating blood lymphocytes in adult patients on rituximab to treat immune thrombocytopenia: circulating number of NK cells is associated with the response at 6 months. Br J Haematol. Published online April 20, 2023. doi:10.1111/bjh.18818

Hanif N, Anwer F. Rituximab. StatPearls [Internet]. Updated September 26, 2022. Accessed May 4, 2023.