Clinically significant respiratory disease that requires mechanical ventilation support or 50% oxygen. Active, uncontrolled infection, or active systemic illness that requires ongoing vasopressor support or mechanical ventilation Requiring mechanical ventilation Subjects requiring vasopressor or mechanical ventilation. Pulmonary failure (requiring mechanical ventilation) not due to active LCH. Adequate respiratory function defined as not requiring supplemental oxygen or mechanical ventilation; oxygen saturation 90% or higher on room air RETREATMENT WITH MODIFIED T-CELLS EXCLUSION CRITERIA: Patient requiring supplemental oxygen or mechanical ventilation Requirement for mechanical ventilation within 7 days prior to Day 1, or sustained oxygen delivery for > 24 hours within 7 days prior to Day 1, or any oxygen requirement within 48 hours prior to Day 1 Adequate respiratory function defined as not requiring supplemental oxygen or mechanical ventilation; oxygen saturation 90% or higher on room air Adequate respiratory function defined as not requiring supplemental oxygen or mechanical ventilation; oxygen saturation 90% or higher on room air Adequate respiratory function defined as not requiring supplemental oxygen or mechanical ventilation; oxygen saturation 90% or higher on room air Subject does not require supplemental oxygen or mechanical ventilation, and oxygen saturation by pulse oximetry is 94% or higher on room air. Require mechanical ventilation or vasopressors for hemodynamic support at the time of randomization. Not requiring supplemental oxygen or mechanical ventilation; oxygen saturation 90% or higher on room air; no dyspnea at rest ELIGIBILITY CRITERIA FOR T-CELL PRODUCT INFUSION: Not requiring supplemental oxygen or mechanical ventilation, oxygen saturation 90% or higher on room air and no dyspnea at rest RETREATMENT WITH MODIFIED T CELLS: Patient requiring supplemental oxygen or mechanical ventilation Endotracheal intubation and mechanical ventilation at any FiO2 ELIGIBILITY CRITERIA TO UNDERGO OPTIONAL T CELL ABLATION\r\n* Research participant has >= 1% CAR T cells in the peripheral blood\r\n* Pulmonary: not requiring supplemental oxygen or mechanical ventilation, oxygen saturation 90% or higher on room air\r\n* Cardiovascular: not requiring pressor support, no symptomatic cardiac arrhythmias, no acute coronary syndrome, or uncontrolled hypertension\r\n* Renal Function: serum creatinine did NOT increase by more than 2.5 fold from baseline (at time of screening)\r\n* Liver Function: adequate liver function defined as total bilirubin =< 3.0 mg/dl \r\n* AST =< 5 x ULN, ALT =< 5 x ULN\r\n* Neurological: research participant without clinically significant encephalopathy/new focal deficits\r\n* Infectious diseases: no clinical evidence of uncontrolled active infectious process Not requiring supplemental oxygen or mechanical ventilation, oxygen saturation 90% or higher on room air (ELIGIBILITY CRITERIA AT TIME OF INFUSION OF GENETICALLY MODIFIED AUTOLOGOUS T CELLS): Not requiring supplemental oxygen or mechanical ventilation, oxygen saturation 90% or higher on room air Not requiring supplemental oxygen or mechanical ventilation, oxygen saturation 90% or higher on room air Pulmonary: not requiring supplemental oxygen or mechanical ventilation, oxygen saturation 90% or higher on room air Pulmonary criteria: not requiring supplemental oxygen or mechanical ventilation, oxygen saturation 90% or higher on room air Require mechanical ventilation or vasopressors for hemodynamic support at the time of enrollment. Clinically significant respiratory disease that requires mechanical ventilation support or 50% oxygen. Patients on mechanical ventilation. Not requiring supplemental oxygen or mechanical ventilation, oxygen saturation 90% or higher on room air Mechanical ventilation, renal replacement therapy, admitted in intensive care until at time of enrollment Has been on mechanical ventilation for > 28 days Currently on invasive mechanical ventilation or noninvasive positive pressure ventilation (CPAP or bilevel positive airway pressure) or requiring > 2LPM supplemental oxygen therapy to maintain O2 saturation > 90% due to hypoxemia Oxygenation index (OI) > 13, but < 37, for two consecutive blood gases which should be separated by at least one hour within 48 hours of the initiation of mechanical ventilation. Respiratory failure requiring mechanical ventilation or non-invasive ventilation Requiring mechanical ventilation Requires mechanical ventilation or is hemodynamically unstable at the time of randomization Respiratory failure requiring greater than 6 Lpm supplemental oxygen (O2) by nasal cannula or mechanical ventilation within the past six weeks Severe dyspnea at rest, due to complications of advanced malignancy, or requiring supplementary oxygen therapy. Severe dyspnea at rest due to complications of advanced malignancy or requiring supplementary oxygen therapy Severe dyspnea at rest due to complications of advanced malignancy or current requirement for continuous oxygen therapy Severe dyspnea at rest due to complications of advanced malignancy, or requiring supplementary oxygen therapy. Receiving supplementary continuous oxygen Dyspnea at rest due to complications of advanced malignancy or other disease requiring continuous oxygen therapy. Current dyspnea at rest of any origin, or other diseases requiring continuous oxygen therapy. Dyspnea at rest or other diseases that require continuous oxygen therapy Severe dyspnea at rest due to complications of advanced malignancy or requiring current continuous oxygen therapy Current dyspnea at rest, owing to complications of advanced malignancy or any requirement for supplemental oxygen to perform activities of daily living History of interstitial lung disease or pneumonitis requiring supplemental oxygen or treatment with oral or intravenously administered corticosteroids Subjects who need daily oxygen therapy Patients requiring any daily supplemental oxygen Subject requires continuous supplemental oxygen for any reason. Additional Exclusion Criteria for Arm B Requirement for daily supplemental oxygen Clinically significant pulmonary compromise, including a requirement for supplemental oxygen use to maintain adequate oxygenation. Dependence on continuous supplemental oxygen use Chronic bronchitis or emphysema requiring oxygen therapy within the last 6 months Clinically significant pulmonary compromise, including a requirement for supplemental oxygen use to maintain adequate oxygenation. Participant has a need for supplemental oxygen with the exception of using previously existing non-invasive continuous positive airway pressure (CPAP) at night. Subjects with a history of interstitial lung disease; patients requiring continuous supplemental oxygen are excluded to avoid possible complications from pneumonitis ARM 2 - A: Pulmonary: patients with a requirement for supplemental oxygen or evidence of moderate-severe COPD by PFTs are permitted to enroll Patients with baseline respiratory insufficiency severe enough to require supplemental oxygen. Patients requiring ventilator support or oxygen supplementation exceeding 40% fraction of inspired oxygen (FiO2) within 14 days of enrollment. Research participant requires supplemental oxygen to keep saturation greater than 95% and the situation is not expected to resolve within 2 weeks Research participant does not require supplemental oxygen to keep saturation greater than 95% and/or does not have presence of any radiographic abnormalities on chest x-ray that are progressive Patients/subjects who need daily oxygen therapy Daily use of oxygen supplementation. Clinically-significant pulmonary compromise, including a requirement for supplemental oxygen use to maintain adequate oxygenation FOR ALL PHASES (Ib AND II): Chronic oxygen therapy Oxyhemoglobin saturation at rest >= 95% (off supplemental oxygen) Use of continuous oxygen Patients/subjects who need daily oxygen therapy Patients requiring oxygen therapy Patients requiring oxygen therapy Patients requiring continuous supplemental oxygen are excluded to avoid possible complications from pneumonitis Need for supplemental oxygen No supplemental oxygen requirement Patient is on supplemental home oxygen ADDITIONAL CRITERIA FOR STUDY CONTINUATION: Patient is on supplemental home oxygen Research participant does not require supplemental oxygen to keep saturation greater than 95% and/or does not have presence of any radiographic abnormalities on chest x-ray that are progressive Research participant requires supplemental oxygen to keep saturation greater than 95% and the situation is not expected to resolve within 2 weeks Continuous oxygen use Within 14 days of study registration: No oxygen requirement on room air or requiring =< 2L supplemental oxygen (O2) Current use of supplemental oxygen Clinically-significant pulmonary compromise, including a requirement for supplemental oxygen use to maintain adequate oxygenation. Idiopathic pulmonary fibrosis or other severe interstitial lung disease that requires oxygen therapy or is thought to require oxygen therapy within 1 year prior to step 1 registration Any patient requiring supplemental oxygen therapy Respiratory insufficiency with oxygen requirement > 4 L nasal cannula Patients must not require daily supplemental oxygen No history of severe chronic obstructive pulmonary disease (COPD) or emphysema or interstitial lung disease currently on home supplemental oxygen; patients with NSCLC with stable COPD or emphysema not requiring supplemental oxygen are eligible No requirement for supplemental oxygen therapy Severe hypoxemia with room air pulmonary arterial oxygen tension (PaO2) < 70, supplemental oxygen dependence, or DLCO < 50% predicted Patients requiring supplemental oxygen Participants requiring any daily supplemental oxygen Known severely impaired lung function, including: • CTCAE grade 2 (or greater) hypoxia (decreased oxygen saturation with exercise [e.g., pulse oximeter <88%]; intermittent supplemental oxygen) Patients requiring supplemental oxygen therapy Patient is on supplemental home oxygen Patients with pulmonary disease limiting daily function or requiring oxygen supplementation Patients on supplemental home oxygen Continuous oxygen use Patients on oxygen May not be on supplemental oxygen Patient must not have a requirement for supplemental oxygen The patient must not be dependent on supplemental oxygen Use of formalin or hyperbaric oxygen treatment Requirement of supplemental oxygen. History of interstitial pneumonitis and/or require supplemental oxygen therapy Requiring supplemental oxygen at more than 2 L/min Dyspnea of any cause requiring supplemental oxygen therapy; Participants requiring any daily supplemental oxygen Patients with history of lung disease currently requiring any pharmacologic or supplemental oxygen treatment Adequate pulmonary function defined as:\r\n* No dyspnea at rest\r\n* No known requirement for supplemental oxygen\r\n* No known active pneumonitis Clinically significant pulmonary hypertension, as defined by the requirement for ongoing pharmacologic treatment or the consistent or intermittent use of supplemental home oxygen. Cohort A: Continuous oxygen use Patient currently requiring supplemental oxygen for his/her daily life Requirement for supplemental oxygen to carry out activities of daily living Patients with active infection defined as:\r\n* Positive blood culture within 48 hours of study registration\r\n* Need for supplemental oxygen or vasopressors within 48 hours of study entry Oxygen saturation <95% on room air by trans-cutaneous method or need for any supplemental oxygenation or ventilatory support, or increase in oxygen supplementation requirement of ?2 litres for subjects with chronic oxygen dependency. For those subjects with a history of chronic hypoxia (without supplemental oxygen), an oxygen saturation of at least 3% below the patient's historical baseline oxygen saturation will satisfy this criterion. Oxygen saturation < 90% despite supplemental oxygen > 6 L/minute. Are receiving chronic oxygen therapy Daily supplemental oxygen Subjects currently on supplemental oxygen support Patients with history of lung disease currently requiring any pharmacologic or supplemental oxygen treatment Chronic supplemental oxygen requirement or hypoxemia < 92% blood oxygen saturation (SpO2) Any patients requiring oxygen at baseline Currently requiring high flow oxygen for oxygenation Supplemental oxygen dependency Patients must be able to walk unassisted without oxygen Supplemental oxygen requirement > 6 L per minute Patients requiring oxygen more than 2 liters No requirement for supplemental oxygen (O2) Patients with history of lung disease currently requiring any supplemental oxygen treatment Clinically significant pulmonary compromise (e.g. require supplemental oxygen) Adequate pulmonary function as assessed by oxygen saturation >= 90% when ambulating and not requiring supplemental oxygen Respiratory disease requiring continuous supplemental oxygen Supplemental oxygen requirement > 6 L per minute Supplemental oxygen requirement > 6 L per minute Oxygen saturation < 90% despite supplemental oxygen > 6 L/min On chronic oxygen Severe hypoxemia with room air partial pressure of oxygen (PaO2) < 70, supplemental oxygen dependence, or DLCO < 50% predicted Hypoxemia (less than 90% saturation with supplemental oxygen) Current use of supplemental oxygen Significant valvular disease, or significant pulmonary disease requiring supplemental oxygen therapy Patients that require supplemental oxygen are excluded Patients requiring continuous supplemental oxygen due to the requirement of spirometry during all imaging studies Patients with history of lung disease currently requiring any pharmacologic or supplemental oxygen treatment Requires daily supplemental oxygen. Patients that require supplemental oxygen are excluded Oxygen saturation >= 90% when ambulating and not requiring supplemental oxygen