Double-Negative T-Cell Reaction in a Case of Meningitis.

Gamma delta T-cells are commonly found in response to infection in mice, whereas this same immunological response has only been reported a few times in vivo in humans. Moreover, gamma delta T-cell response in cerebral spinal fluid samples in conjunction with meningitis has never been described in medical literature to date. Thus, we describe a 64-year-old male who presented with altered mental status, fever, and neck stiffness. After lumbar puncture revealed elevated glucose, protein, lactate dehydrogenase, and white blood cell count, further cytologic analysis was indicated. The CSF showed a markedly hypercellular sample with a lymphocytic pleocytosis, including some enlarged forms with irregular nuclear contours, and rare macrophage containing intracytoplasmic bacteria. Lymphocyte immunophenotyping was performed via flow cytometric analysis, which ultimately revealed a prominent CD4/CD8 negative T-cell population, suggestive of a gamma delta T-cell population. Thus, an initial suspicion of malignancy was considered but was ruled out due to the absence of mass lesion on imaging and overall features including heterogenous lymphocyte morphology. Shortly after, gram stain and cultures were obtained revealing . Unfortunately, the patient rapidly succumbed to disease following the diagnosis of meningitis. Studies suggest that gamma delta T-cells are activated by the protein components of and thus have been found to be an important mediator of resistance to infection. Studies have also discovered that the level of activation for these T-cells appears to be tissue specific and dose dependent, with most cases occurring within visceral organs. Hence, we herein present the first case of gamma delta T-cell activation due to within the cerebral spinal fluid of a human patient.