Delayed skin hypersensitivity as indicator of T-cell function in three population groups.

Immunological differences between a rural under-developed black population with a low incidence of rheumatoid arthritis, and living according to old traditional ways have been compared with an urban black and urban Caucasian population with a high incidence of the disease. A delayed skin hypersensitivity test for cell-mediated immunity with seven antigens and control was used. The rural group showed a statistically significant inhibition of cell-mediated immunity with 37% showing an anergic response. A matched Caucasian group showed a more marked response while an urban black group occupied an intermediate position. The 37% anergic response in our rural group was seen despite the fact that they were very healthy and their immune systems resisted multiple parasitic and infective onslaughts. From this data interpretation of an anergic response to multiple skin antigen tests in peoples from under-developed populations must be approached with great caution. Whether this altered cell-mediated immunity plays a role in the low incidence of rheumatoid arthritis in under-developed peoples is still speculative.