PHA Responsiveness and Subpopulations of Circulating Lymphocytes in Pernicious Anemia

Lymphocyte transformation responses to the mitogen phytohemagglutinin (PHA) were measured in 20 patients with proven pernicious anemia (PA) and 20 matched controls using ³H-thymidine label. The patients with PA showed significant depression of lymphocyte transformation to the three doses of PHA employed, as judged by beta counting; however, radioautographic examination of PHA-stimulated cells indicated that the results were due to a failure of intranuclear incorporation of ³H-thymidine by PA lymphocytes, rather than a failure of PHA to induce blastogenesis. The percentages and numbers of T and B lymphocytes in peripheral blood were measured in 30 patients and controls by rosette and immunofluorescence techniques, respectively. There was no significant difference in the B cell subpopulations between patients and controls; the T cell subpopulation was slightly lower in the PA patients (mean 62.4%) than in the controls (mean 65.5%), but the difference was not statistically significant. The depressed uptake of ³H-thymidine by stimulated lymphocytes in PA would seem to reflect a chemical defect rather than inherent immunologic abnormality.