265:
Low class switched memory B cells predicts the need for continued need for replacement immunoglobulin therapy post Rituximab use and adequate numeric B cell reconstitution
Saturday, March 3, 2018: 2:45 PM
S310AB (Convention Center)
Caitlin MG McNulty, MD,
RATIONALE: Rituximab (anti CD20 monoclonal antibody) is a B cell depleting agent with a wide range of indications and despite adequate numeric B cell re-constitution, there are patients who experience infectious complications and need supplemental immunoglobulin therapies. There are currently no predictors for the need for continued need for supplemental immunoglobulin therapy in this population.

METHODS: We analyzed the clinical and laboratory correlates of five patients who experienced infectious complications post rituximab use and needed supplemental immunoglobulin therapy.

RESULTS: Five patients were evaluated by our adult immune deficiency service in 2016-2017 who had received Rituximab, four of whom had Follicular Lymphoma and one had diffuse large B cell lymphoma. The median time since Rituximab therapy was 7.59 yrs. (IQR 6.5-9.6 yrs.). The median age at Rituximab treatment was 63yrs (IQR 44-66 yrs.). IgG levels at start of supplemental IgG therapy were <400mg/dl (median 282mg/dl). B cell immunophenotyping was obtained in 4/5 patients which showed decreased class switched memory B cells(CSMB) (CD27+M-D-), median: 0.25%,( normal range: 2.3-26.5%) absolute count :0.55 ( normal range: 7-61cells/mcL), despite adequate B cell reconstitution:median:229 cells/mcL ( normal range: 90-539 cells/mcL).

CONCLUSIONS: Decreased CSMB cells predict the need for continued need for replacement immunoglobulin therapy and could be considered as a prediction parameter. We plan to undertake a larger study of our lymphoma cohort.