Pneumocystic carinii pneumonia in a term newborn infant with a transiently depressed T lymphocyte count, primarily of cells carrying the CD4 antigen

A term infant without infection by human immunodeficlency virus had pneumocystis pneumonia at 17 days of life. Initial counts of T lymphocytes carrying the CD4 antigen were ≈50% of the lower limits of normal; later the counts of T lymphocytes carrying the CD3 and CD8 antigens decreased as well. By 7 weeks after resolution of the pneumonia, CD3⁺, CD4⁺ and CD8⁺ cell counts had returned to normal. These observations suggest that a primary transient deficiency of T cell production or maturation, especially involving CD4⁺ cells, may occur in otherwise normal newborn infants.