The effect of steroids on peripheral blood lymphocytes containing parallel tubular arrays.

The response of lymphocytes containing cytoplasmic inclusions called parallel tubular arrays (PTA) was determined after the administration of the glucocorticoid dexamethasone to 10 healthy volunteers. The percentage of these lymphocytes was found to increase during the lymphopenia induced by steroid administration. The size and number of parallel tubular arrays per cell showed no differences before and after steroid administration, indicating that the increase was a result of a change in the proportion of whole cells. This indicates, for the first time, that a morphologically defined population of lymphocytes from the normal peripheral circulation has been linked to a specific response, ie, steroid resistance. The possible mechanism of steroid resistance is discussed.