IDENTIFICATION OF CELL SUBSETS EXPRESSING INTRACYTOPLASMIC CYTOKINES WITHIN HIV-1-INFECTED LYMPH-NODES

Objective: To describe the endogenous cytokine profile of HIV-l-infect ed lymph nodes (LN) and to identify the phenotype of individual cells expressing intracytoplasmic cytokines. Design and methods: Whole LN bi opsies were collected from three HIV-seronegative controls and four HI V-I-positive individuals with persistent generalized lymphadenopathy. Three had established infection (Centers for Disease Control and Preve ntion 1993 criteria, stages A2, C1 and C3) and one was undergoing sero conversion illness. A combination of three methods was used to assess the impact of HIV-1 on LN architecture and endogenous cytokine express ion. Immunocytochemistry was used to locate follicular dendritic cells (FDC), interdigitating cells and T and B cells. Reverse transcriptase -polymerase chain reaction was used to assess mRNA for interleukin (IL )-1 beta, IL-2, IL-4, IL-6, IL-10, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma in collagenase-digested LN cells. Three-col our flow cytometry was used to identify intracytoplasmic cytokine expr ession within cell subsets. Results: Germinal center (GC) hyperplasia was observed in LN from two patients with established HIV-1 infection, and the third, coinfected with Mycobacterium tuberculosis, showed ext ensive necrosis. In the patient undergoing seroconversion, there was a n extensive FDC network within the expanded and confluent GC which cov ered expansive areas of the LN. There was varied expression of IL-1 be ta, IL-4, IL-6, IL-10 and TNF-a mRNA from the four HIV-l-infected LN a nd the patient undergoing serocon-version showed evidence for a mixed cytokine profile, which also included IL-2 and IFN-gamma. Flow cytomet ry revealed intracytoplasmic IL-IP protein restricted to cells express ing CD19, CD21 and CD38 antigens. Conclusions: Cytokines were detected in freshly isolated HIV-1-infected LN cells without requiring an exog enous stimulus. Seroconversion was associated with an expanded FDC net work within enlarged GC, bounded by defined mantle zones containing B cells. There was diverse cytokine mRNA expression and IL-1 beta protei n was restricted to cells expressing B-cell-associated antigens.