Among sheep producers, the parasitic nematode Haemonchus contortus is a major animal health concern. Caribbean hair sheep are more resistant than conventional wool breeds to this blood-feeding, abomasal parasite. Our objective was to determine differences in the immune response associated with parasite-resistant hair and susceptible wool lambs infected with 10,000 H. contortus and in uninfected controls. Animals were sacrificed and abomasum and lymph node tissues were collected at 3 or 27 days post-infection (PI), and for controls on day 17, 27, or 38 relative to d 0 of infected animals. Blood and fecal samples were collected throughout the study. Lower fecal egg counts, higher packed cell volumes, and heavier lymph nodes of infected hair compared to wool lambs, suggests hair lambs have increased parasite resistance. Greater tissue infiltration of eosinophils (P < 0.05) was observed in hair compared to wool sheep by 3 days PI, with no breed differences in globule leukocytes. Total serum IgA and IgE were greater in control hair versus wool sheep (P < 0.05). After 3, 5, and 21 of infection, total serum IgA (P< 0.05), total lymph node IgE (P < 0.01), but not total serum IgE were greater in hair sheep compared to wool sheep. Gene expression was measured between hair and wool lambs for abomasal and lymph node tissues using bovine cDNA microarrays and real-time RT-PCR. Microarray analysis revealed cell survival, endosome function, gut motility, and anti-coagulation pathways are important in abomasal and lymph node tissues during H. contortus infection. Immune genes, including IL-4, IL-4 Ra, IL-12 Rb1, and IL-12 Rb2, are also highly represented in abomasal or lymph node tissue of infected animals. Eleven genes were evaluated using real-time RT-PCR and included TH1 and TH2 cytokines, cytokine receptors, and IgE. Parasite infection leads to increased expression of IL-13 and IgE in both tissues and breeds when compared to control animals. Breed comparison of gene expression shows resistant hair sheep produce a stronger modified TH2-type immune response during infection. Differential cell infiltration, antibody production, and regulation of TH2 cytokines between breeds may be partially responsible for differences in parasite resistance. / Ph. D.

INTRODUCTION: Chimeric antigen receptor (CAR) T-cell therapy is a new treatment for hematologic malignancies including aggressive B-cell non-Hodgkin’s lymphoma (NHL). Although it has provided an effective treatment option for patients who have few options, CAR T-cell therapy does have many associated toxicities. Prolonged cytopenias are one of the lesser understood toxicities that can affect upwards of 40% of patients. METHODS: In this retrospective study, we reviewed 106 patients who received commercial CAR T-cell therapy between November 2017 and September 2019. Prolonged cytopenias were defined as having absolute neutrophil count (ANC) <1000/mm3, platelets (PLT) <50,000/mm3, and/or hemoglobin (Hgb) <10 g/dL at least once after 30 days post-CAR T-cell infusion. Furthermore, if only one incidence of cytopenia was recorded 30 days post infusion, we required that the patient had to have received either a transfusion or granulocyte-colony stimulating factor (GCSF) after the date of the recorded cytopenic value to be considered a part of the cytopenic cohort. RESULTS: 22 patients met the criteria of having prolonged cytopenias. 64% of the cytopenic cohort had >1 type of prolonged cytopenias. Anemia was the most prevalent affecting 72% of cytopenic patients. The length of time from diagnosis of aggressive B-cell NHL to date of CAR T-cell infusion was found to be positively correlated with an increased risk of developing prolonged cytopenias following CAR T-cell therapy. Additional risk factors associated with an increased risk of delayed cytopenias by univariate analysis included neutropenia on the day of infusion (day 0), a high C-reactive protein (CRP) before lymphodepletion and on day 0, day 0 PLT count, and Hgb before lymphodepletion and on day 0. On multivariate analysis, only high CRP before lymphodepletion was associated with an increased risk of prolonged cytopenias while high ferritin and PLT values on day 0 were associated with not developing prolonged cytopenias. There was no statistical difference between the cytopenic and non-cytopenic cohorts in rates of progression free survival (PFS) and overall survival (OS). Also, no difference was seen in rates or severity of other toxicities between cohorts. 41% of the cytopenic cohort experienced infectious complications post-infusion with one patient dying from their infectious complications. However, there was no association with incidence of infection and prolonged cytopenias when compared to the incidence of infection in the non-cytopenic cohort. CONCLUSIONS: A longer time from diagnosis of aggressive B-cell NHL to time of CAR T-cell infusion was associated with prolonged cytopenias while the number of lines of prior chemotherapy and rate of prior high dose chemotherapy with an autologous stem cell transplant (HD-ASCT) were not associated. It would be valuable to confirm this association and why it is associated since the other two factors were not. We lacked bone marrow biopsies before CAR T-cell infusion and did not have bone marrow biopsies for many patients after CAR T-cell infusion. It would be beneficial to collect data regarding bone marrow biopsies from these time points to highlight any changes that could be related to CAR T-cell therapy. Cytogenetic information of individual patient’s diseases would be worth analyzing to help determine if there are biological factors associated with prolonged cytopenias in response to CAR T-cell therapy. Additional studies should investigate the laboratory values we found to have associations with either cohort to help identify possible predictive values providers could use to identify patients at higher risk of having prolonged cytopenias. There is also a need to see if specific prior chemotherapy regimens increase a patient’s risk of having prolonged cytopenias. Overall, since prolonged cytopenias after CAR T-cell infusions have not been heavily investigated, further investigation is needed to better understand the predictive factors and identify possible mechanisms of prolonged cytopenias seen in CAR T-cell patients.