The official abbreviation of the journal title "Annual Review of Immunology" is Annu Rev Immunol, Annu Rev Immunol is a standardized way to abstract, index, and reference a particular journal according to ISO 4. For example, if you’re looking for a scientific journal that particularly publishes research related to (field of study) in (country/location) then you can gather the required information from (Annual Review of Immunology).
This abbreviation of the title meets all the criteria issued by ISO4 for choosing journal title abbreviations.
The International Organization for Standardization (ISO) has appointed the ISSN (International Standard Serial Number) International Centre as the registration authority for ISO 4. ISO 4 (Information and documentation – Rules for the abbreviation of title words and titles of publications) is an international standard that marks a static system for the abbreviation of serial publication titles. According to ISO4, terms are abbreviated according to LTWA. It is a list that is filled with all the uniform abbreviations used for words in scientific excerpts. It is based on ISO 4.
List of Title Word Abbreviations or LTWA is standard abbreviations for words commonly found in serial titles. LTWA includes has more than 56,000 words and their abbreviations in about 65 languages, it is a vast database. These abbreviated words serve as the basis for constituting “abbreviated key titles” published in the ISSN Register. So (journal-title) might consist of words from LTWA that are formed according to ISO4 by ISSN.