Disseminated Rhodococcus equi infection in a patient with diffuse large B-cell lymphoma treated with immunotherapy.

Immunotherapies can lead to an immune compromised state that can allow for opportunistic pathogens such as Rhodococcus to flourish. The vast majority of Rhodococcus infections occur in immunocompromised hosts. Here we describe disseminated Rhodococcus equi infection in a patient with diffuse large B-cell lymphoma treated with immunotherapy. Infection with Rhodococcus can be diagnosed with the aid of cytomorphology and histochemical findings and the organism confirmed by sequencing. In conclusion, Rhodococcus should be considered in the differential of granulomatous inflammation in immunocompromised individuals treated with immunotherapies.

A 3-step method for preparing cryopreserved samples of apheresis products for post-thaw analysis yields a higher percentage of viable cells.

BACKGROUND: Standard flow cytometry protocols for CD34+ cell enumeration designed for fresh samples are not appropriate for cryopreserved products. Special protocols have been developed to remove the cryoprotectant by quickly washing a freshly thawed sample. Exposing cells to a large volume of hypotonic solution and subsequent washing process was hypothesized to cause lab-induced cell death. Moreover, standard gating strategies must be altered to avoid reporting falsely high viabilities. STUDY DESIGN AND METHODS: We developed a novel method whereby thawed samples were diluted step-wise to 1:2 by 3 additions of 1/3 sample volume using 1% Human Albumin in Dextran 40 (10% Low Molecular Weight Dextran in 0.9% NaCl) separated by 5 min between each addition. An additional 1:10 dilution was required to obtain a desired cell concentration for flow cytometry testing resulting in a 1:20 dilution. RESULTS: Twenty samples were tested simultaneously in a method comparison; the new method demonstrated significant increases in mean cell viabilities for white blood cells, hematopoietic progenitor cells, and T cells as well as reduced standard deviations for each parameter. DISCUSSION: Slow, step-wise dilutions of freshly thawed samples of cryopreserved apheresis products to 1:20 yielded higher and more precise viability measurements compared to quickly washing samples to remove DMSO.