Osteoporosis and Immunity Changes of Cell-mediated Immunity and T-cell Subsets Responding to la(OH) vitamin D₃

Postmenopausal or senile osteoporosis has been ascribed to endocrine imbalance, nutritional deficiency, physical immobilization and genetic disposition until immunological abnormality has recently been held responsible in view of the female preponderance, increase with age, prevalence around rheumatoid joint and lymphokine-stimulated osteoclast-osteoblast imbalance characterizing osteoporosis. Tuberculin reaction became increasingly negative with advancing age especially in osteoporotics. Negative tuberculin reactors were found more frequently in osteoporotics with compression fracture and low bone mineral content (BMC) than in non-osteoporotics of the same age. Administration of 0.5μg/day 1α(OH) vitamin D3 changed negative tuberculin reaction into positive in osteoporotics but not in non-osteoporotics. Total lymphocyte count and T-lymphocyte number were similar between osteoporotics and non-osteo-porotics but OKT4/OKT8 (helper/suppresser) ratio was significantly higher in osteoporotics than in non-osteoporotic controls of the same age. A negative correlation was found between OKT4/OKT8 and BMC. Administration of 0.5gμ/day 1α(OH) vitamin D3 for 1 month decreased the elevated OKT4/OKT8 in osteoporotics. Correction by 1α(OH) vitamine D3 of high OKT4/OKT8 ratio and negative tuberculin reaction indicating decreased cell-mediated immunity characterizing osteoporosis may explain some of its therapeutic efficacy.