Gastritis

A 37-year-old woman with a history of Hashimoto's thyroiditis presents to the primary care physician with a several-month history of fatigue and pain after eating. The patient reports burning pain approximately twenty to thirty minutes after every meal with associated nausea. She reports that she drinks one glass of wine with dinner every night. She does not have worsening of the symptoms with any particular food items, and she has not had any recent changes in diet.  Temperature is 37°C (98.6°F), pulse is 84/min, respirations are 14/min and blood pressure is 110/62 mmHg. Physical exam shows conjunctival pallor as well as a smoothened and shiny tongue, fissures at the angles of the lips, and a wide-based gait. Laboratory findings are demonstrated below:  
 

Laboratory value	Result
CBC, Serum
Hemoglobin	10.2  g/dL
Hematocrit	33.6%
Leukocyte count	9,000 /mm3
Platelet count	200,000/mm3
MCV	109 fL
RDW	11.5-14.5%
Serum
Sodium	134 mEq/L
Potassium	4.2 mEq/L
Chloride	96 mEq/L
BUN	37 mg/dL
Creatinine	1.8 mg/dL
Albumin	3.5  g/dL

Which of the following best describes the mechanism underlying this patient’s clinical manifestations?